Better accounting begets better water management

by Jay Lund

groundwater pump

Source: Escriva-Bou et al. 2016

Sustainable use of groundwater in California will require major changes in groundwater management, use, and recharge.  Under the 2014 Sustainable Groundwater Management Act, groundwater basins as a whole are responsible for sustainability.  But millions of people and thousands of governments and private land managers must recharge more water and pump less to achieve this goal, without disrupting existing surface water rights.  How can responsibility and credit for groundwater use and recharge be developed and assessed without debilitating water wars?

State-overseen accounting already civilizes common disputes involving land ownership, money, gasoline, electricity, and weights and measures generally.  Local water utilities measure and estimate water quantities to improve accountability, transparency, and management for their own customers, regulators, system managers, and financiers.  Some groundwater basins, such as Orange County, Santa Clara Valley, and some adjudicated groundwater basins have rudimentary accounting systems to assess fees for groundwater pumping, plan for recharge, or limit pumping.  But California overall lacks a strong unified system of water accounting, particularly for groundwater.

California should join other advanced economies in dry regions and institute a formal water accounting system.  Australia, Spain, Colorado, Texas, and other western states already have stronger and more unified water accounting systems.  A report released last week by the Public Policy Institute of California, in collaboration with university researchers, details 12 lessons for water accounting in California and reviews water accounting in Australia, Spain, and 11 other western states.  The accounting systems vary in their details, but all have a single authoritative accounting of water flows based on measurements and estimates of water availability, use, and flows returning to streams and aquifers after use.

Groundwater Rights

Source: Escriva-Bou et al. 2016


For groundwater, stronger water accounting would transparently inform regulators, users, and the public alike on the balance of groundwater use and recharge and the responsibility and credit for pumping, recharge, and net pumping.  Such accounting is needed to assess basin sustainability, assess liability for pumping and credit for recharge, as well as the natural flows of water underground into and between basins.  Without such accounting, agreements, rights, and allocations regarding water are difficult to make and enforce, begetting excessive legal expenses and delays while basin management remains unsustainable.  An accounting framework also makes detection and correction of errors more transparent and efficient.

A stronger state system for water accounting also would benefit the administration of surface water rights, environmental flows, water markets, and more integrated science-based management, which currently suffer from lack of a strong common state accounting system.  The many partial water accounting systems maintained by separate state and local agencies and programs sometimes compound water disputes and weaken each other more than offering common ground to civilize disputes.  A common water accounting system would help civilize and enlighten a host of chronic water conflicts, and provide a scientific basis for resolving many disputes.

How can California get to a stronger and more useful water accounting system?  Australia, motivated by its great 12-year drought, took 10 years to revamp and solidify its water accounting.  California might begin with an independently-led task force involving the major state agencies along with independent experts and stakeholders, commissioned to make recommendations to the Governor’s office and the legislature.

California is already paying most of the cost needed for a credible water accounting system.  Major water utilities already measure or estimate their water sources and uses, usually in automated “supervisory control and data acquisition” (SCADA) systems.  State forethought to organize and automate collection of these data would allow transparent, accountable, timely, and inexpensive incorporation of such existing data for water accounting.  (Smaller users will take more time, but are less important overall.)  The hardest part is organizing  state agencies around a single coherent water accounting framework, which can be supported by locally-collected data and integrated with regional computer models.

Civilizing water conflicts begins with data and an accounting framework.

Jay Lund is a professor of civil and environmental engineering and director of the Center for Watershed Sciences at UC Davis.

Further reading

Alvar Escriva-Bou, Henry McCann, Ellen Hanak, Jay Lund, and Brian Gray (2016), Improving California’s Water Accounting, 28 pp. Public Policy Institute of California, San Francisco, CA.

Alvar Escriva-Bou, Henry McCann, Elisa Blanco, Brian Gray, Ellen Hanak, Jay Lund, Bonnie Magnuson-Skeels, and Andrew Tweet (2016), Improving California’s Water Accounting – Technical Appendix, 177 pp. Public Policy Institute of California, San Francisco, CA.

Improving California’s Water Accounting, report release webcast, Public Policy Institute of California, San Francisco, CA.

Brian Gray, Ellen Hanak, Richard Frank, Richard Howitt, Jay Lund, Leon Szeptycki, Barton “Buzz” Thompson (2015), Allocating California’s Water: Directions for Reform, Public Policy Institute of California, San Francisco, CA.

Posted in California Water, Groundwater, Planning and Management, Sustainability, Uncategorized | Tagged | 3 Comments

St. Helena, California: Dealing with a Field-of-Dreams Levee, Residual Risk, and a Flood of Controversy

by Nicholas Pinter

A new $37.2[1] million levee in the town of St. Helena, on the floodplain of the Napa River, has a colorful history and has been stirring local acrimony since its inception.  This project illustrates both the attraction of levee protection, in this case protecting a low-income neighborhood (“low income” by Napa standards) hit by disastrous flooding in 1986 and again in 1995, as well as pitfalls of this strategy for long-term risk management.  There are clearly positive elements of the St. Helena levee project, but also numerous missteps that have mired the project in dissent and even, opponents argue, threaten to bankrupt the town.  With important planning and zoning decisions now pending, the St. Helena levee is a case study for other communities to examine before they consider all of the options for flood-risk management.

After the release of a recent journal article on levee protection, one reporter tried to wake me up with the following opening question – “Prof. Pinter, why do you hate levees?”  I laughed in appreciation of a good icebreaker, and then explained how levees, floodwalls, and other structural protections are valuable tools in a diverse toolkit used to manage flood risk.  But levees also come with adverse consequences that need to be rigorously evaluated and balanced against their potential benefits.  Those negative impacts and the need for careful evaluation are often lost in the rush to build new levees or enlarge existing structures, typically in the aftermath of a damaging flood.

St. Helena is a town of about 6,000 people along the Napa River about 20 miles upstream of the City of Napa.  The river there is small, averaging just 46.7 cubic feet per second (cfs) of flow over the duration of record, but subject to flash flooding after intense local rainstorms.  Since 1862, 28 major floods have struck the Napa Valley[2], including 1955, 1963, 1967, 1973, 1978, 1981, 1983, 1986, 1993, 1995, 2002, and 2006.  Most of St. Helena is located a safe distance from the river, but starting in the 1970s, the Vineyard Valley area was developed, including 468 homes, apartments, and mobile homes at risk of flooding[3].  Most of these are in what is now mapped by FEMA as the so-called 100-year floodplain.  During the five-year review process for development of the mobile home park, local residents report that the issue of flood risk was never raised.

Napa Flood

Figure 1 –  The Vineyard Valley neighborhood of St. Helena under water during the 1986 flood.

Intense rain events hit the upper Napa Valley in February of 1986 and again in March of 1995, sending the Napa River over its banks and into the new Vineyard Valley development.  Damages in each event were estimated at over $50 million in St. Helena alone.  During the 1995 flood, over 400 residents of St. Helena were evacuated, and 200 mobile homes in Vineyard Valley were declared a total loss.  In both 1986 and 1995, other communities such as Calistoga and Yountville also were hard-hit, including inundation of much of downtown Napa.  As described by the Napa Valley Register, “Overnight, the Napa River swelled from a modest tributary of San Francisco Bay to a wrathful Amazon.”  The 1986 flood killed three people, forced the evacuation of over 2,500, and caused total damages estimated at $100 million2.

A typical pattern in flood response is that it takes a one-two punch to motivate any large-scale action to address flood risk.  The 1995 flood in Napa was that second punch.  Surveying the damage, Napa County officials dusted off a flood-control plan initially drafted by the Corps of Engineers but defeated by a voter referendum in the 1970s.  The original Corps flood control plan was considerably reworked and, particularly in the City of Napa, many forward-thinking elements were added, including channel habitat preservation and reconnection of the historic floodplain.  Flood control was now put to the voters again, in the form of Measure A, a half-percent county sales tax, which was passed in March of 1998 with a two-thirds voter majority.  With local cost-share funding secured through the referendum, Napa County began moving forward with the large-scale flood plan in Napa, with smaller portions of the funding apportioned to other communities along the river.

St Helena plans

Figure 2 –  The positive side of flood control. As part of the St. Helena project, a total of 17 mobile homes were permanently and the flood wall set back from the river.

In St. Helena, plans were drawn up that focused on a large levee and floodwall to protect the Vineyard Valley area, as well as several other elements.  These other elements of the project included bank stabilization, removal of a channel constriction, internal stormwater management, and excavation of a storage area outside the levee (a “terrace,” the project calls it) planted in native vegetation.  The channel restriction, for example, involved the removal of 17 mobile homes and the associated land closest to the river, which opened that area to better pass flood flows.  This bend in the river channel represented a chokepoint during floods, significantly obstructing flow and raising water levels in that area and upstream.  Removal of these homesites and augmenting the conveyance capacity of the channel at this chokepoint certainly lowered flood danger by both reducing at-risk infrastructure and by lowering water levels during future floods.

Although the St. Helena project included several forward-thinking elements, it remained much more of an “old school” structural flood-control plan than what was implemented in Napa.  The St. Helena plan centered on approximately 2,000 ft of floodwall surrounding the Vineyard Valley mobile home park and another ~2,000 ft of levee that extends from the floodwall to the north and west.  As now required of urban levees in California, the system protects to the “200-year” level – that is, designers of the levee and floodwall have affirmed that they will keep out floods up to those with a 0.5% chance of occurring in any year.

On a map the St. Helena levee is relatively small, a tiny fraction of the length of the systems that protect the Central Valley or great alluvial floodplains of the Midwest.  But its height is impressive.  Standing on the new levee crest above the Napa River, one can almost imagine looking out on the Sacramento or Mississippi River.  The levee is also proportionally wide, with a crest 15-20+ feet across, wide enough to meet requirements for much larger rivers and floodplains.  Wide enough, in fact, to carry two full lanes of traffic.  Indeed, the initial St. Helena planning documents[4] called for a multi-function levee that would also serve as a new roadway.  This new road would have crossed the floodplain and the river across a new bridge, connecting St. Helena to the Silverado “wine trail” on the northeast bank.  Currently that connection is across the Pope Street bridge, a historic stone structure built in 1894 and so narrow that it is terrifying to cross even when the driver coming the other way hasn’t spent the afternoon sampling the latest vintages.  Using flood-control funding to simultaneously serve another goal might not be illegal, but it raises questions about priorities in design details.  In this case, the proposed bridge link was rejected after litigation focused on its environmental impacts, but before levee construction.  Nevertheless, the width of the St. Helena levee retained the width of a road to nowhere, as well as – importantly – a path that took the levee far wide of the housing it was funded to protect, enclosing a broad swath of floodplain undeveloped and empty except for rows of grapevines.  More on this in a moment.

Another interesting aspect of the St. Helena levee is the funding to plan and design the project.  The city obtained an $8 million grant from FEMA’s Hazard Mitigation Grant Program (HMGP).  HMGP uses a slice of FEMA’s total disaster-related funds to promote “mitigation,” meaning actions taken by communities to lower their overall exposure to future disasters.  Flood-mitigation strategies favored by FEMA nationwide include buyouts and relocation of repeatedly flooded homes or elevation of floodplain structures up beyond the reach of future floods.

FEMA carefully monitors HMGP projects to make sure that taxpayer funds are used for their intended purpose.  In 2013, when FEMA audited St. Helena, the city was unable to account for a large block of HMGP money.  Among project expenditures, the city had spent $1.64 million on lobbying expenses, reportedly including lavish entertainment expenses in Washington aimed at securing Army Corps of Engineers and other federal funding for levee construction.  When FEMA reviewed the city’s books, it disallowed $1.9 million in expenses, requiring St. Helena to withdraw this amount from its operational accounts.  Further local acrimony ensued because the city repaid the FEMA money without adequately, some argue, disclosing the financial missteps and the resulting impacts on city finances.  This repayment resulted in a $1.5 million budget deficit and significant cuts to city services.

The details above are a selection of the complaints voiced by local levee opponents in St. Helena.  This dissent contrasts with the broad consensus surrounding the much larger flood-control measures implemented in the City of Napa.  Large public projects never reach perfect consensus, but the Napa Project solicited input from a broad range of stakeholders and integrated these opinions in final project designs.  In contrast, the St. Helena project continues to roil that community even now that the levee is complete and a done-deal.

The final shoe – probably the most problematic element of the St. Helena flood-control debate – is now dropping, five years after the levee’s completion.  The current issue results from the unusual pathway of the levee, which sweeps well north and west of the neighborhoods previously flooded and includes 16.9 acres of undeveloped vineyard land.  Undeveloped until now, that is.  Just 17 days before the passage of Measure A, the mechanism that funded large-scale flood engineering throughout Napa County, much of the empty floodplain land behind the St. Helena levee was purchased by a private developer.  On Sept. 8, 2010 the developer submitted plans to convert the empty agricultural land behind the levee into high-density residential development, including 87 new residential units[5]. This despite an explicit provision in Measure A that “none of these projects are intended or designed to encourage population growth.”

Levee Sniff Test

Figure 3 –  The Levee Sniff Test

My research group has worked hand-in-hand with floodplain residents to provide them planning guidance and technical expertise.  We’ve also studied levee projects that would increase flood heights for neighbors, increase long-term flood risk, or degrade habitats, sometimes in exchange for very limited local flood-protection benefits.  After struggling with this balancing act time and again, we’ve proposed a three-step “levee sniff test” to preliminarily judge any proposal.  New or enlarged levees and floodwalls may be an appropriate solution if the system is designed to protect floodplain infrastructure that is:

  1. concentrated,
  2. high in value, and
  3. pre-existing.

The most crucial – and often the most politically fraught – of these criteria is the third.  The worst case is construction of “field of dreams” levees – new, expensive, often muscular levees surrounding undeveloped or sparsely occupied floodplain land.  “Build it and they will come” – field-of-dreams levees are meant to attract new construction and development on the floodplain.  Political leaders see expansion of their local tax base, and developers salivate over the prospect of transforming low-cost floodplain land into urban real estate as soon as the new levee “solves the problem of flooding forever.”

By intent or by accident, the St. Helena project created a “field of dreams” levee.  The original position of the levee was set by the desire of the city to piggyback a long-sought transportation project onto available flood-control funding.  A private developer saw an opportunity for windfall profits and snapped up this floodplain acreage.  What remains unclear is why, when plans for the roadway were scrapped, did St. Helena not downsize its levee?  Local levee opponents see nefarious motives here, and the optics are not good.  In 2008-2009, local residents had proposed several possible levee alignments that hugged the edges of existing neighborhoods that needed protection.  These alternatives would have eliminated the “field of dreams” issues, cut construction costs, and would have significantly reduced future flood levels for neighboring properties outside the levee.  But these alternatives were rejected at the April 14, 2009 meeting of the City Council.  Why? Perhaps simply a result of frustration at the grassroots opposition and the desire to move forward with the existing blueprint, however much conditions had changed since those plans were drawn up.

“Residual Risk – the small but real possibility that a levee may fail or be overtopped during future floods.”

So past mistakes aside, why not fill in every square inch of land behind a levee once you’ve got one?  The problem with levees, and with field-of-dreams levees above all, is that no type of structural flood protection can ever reduce the flood risk to zero.  Even the strongest levee or floodwall carries a “residual risk” of failure or overtopping during large floods.  Furthermore, having flood waters pour over or burst through a tall barrier turns the gradual process of floodplain inundation into a much more violent, dangerous, and damaging event.  The history of occupation of U.S. floodplains is a history of levee failures, with headlines almost every year bringing footage of disastrous levee failures somewhere in the country.  One levee system on the Mississippi River, not an atypical one, was breached 14 times through its history, only to be patched and raised each time, in the process driving up flood levels for the next event and contributing to the next failure.  Expert after expert, blue ribbon panel after panel, has implored engineers, local leaders, and floodplain residents to not forget about residual risk.  Brig. Gen. (Ret.) Gerald Galloway, former commander of the US Army Corps of Engineers puts it this way, “Let no one believe that because you are behind a levee, you are safe” (Galloway, 2005).  The point has also been made more bluntly, “There are two kinds of levees … [t]hose that have failed and those that will fail” (Martindale and Osman, 2010).

“Developers and home builders may be gone, but residents of Natomas will be there and are the ones who are rolling the residual-risk dice year after year.”

Neglecting residual risk of flooding behind levees creates a false sense of security for residents and a lunatic calculus in which the local community can find itself with far greater long-term flood risk than before the levee was built.

California has made these mistakes before.  In fact, the leading example of a “field of dreams” levee, discussed in floodplain management circles around the world, is Natomas on the northwest side of Sacramento.  The Natomas Basin is ringed by 42 miles of levees, encompassing approximately 53,000 acres of the floodplains of the Sacramento and American Rivers.  This land was sparsely populated until roughly 1990.  Despite a tangled history, the Natomas system was built and they did come.  On-going levee construction, particularly improvements initiated in 1992, ushered in a wave of development.  As of 2010, Natomas was home to over 22,800 structures, the large majority of them residential units and home to more than 90,000 people[6].  The City of Sacramento currently plans to permit up to 1,000 additional single-family homes per year, 500 multifamily residential units per year, and unlimited industrial, commercial, and retail construction behind this levee[7].  Today, total property in Natomas at risk of flood damage, should the levee fail or be overtopped, exceeds $8.5 billion, with flood depths that could reach 25 feet[8].  Heroic efforts are now underway by the Sacramento Area Flood Control Agency, the California Central Valley Flood Protection Board, and the Corps of Engineers to patch deficiencies in the Natomas levee and raise the overall protection provided by the system.  When that huge – and hugely expensive – effort is complete, the State of California, the Corps, and FEMA will sign off that they have reduced the statistical chance of catastrophic flooding in Natomas to 0.5% per year (less than once every 200 years, on average).  That is a high level of protection by US standards, and engineers and leaders who are implementing the project will be justifiably proud of their accomplishment.

But … our country’s 400+ year history with levees also tells us that such claims of almost complete flood protection have often been repeated, and almost always were over-stated.  Lots of reasons why this has happened in the past, and many of those reasons hold true for the future.  But even at face value, a 0.5% exceedance probability for a system now protecting $8.5 billion in property translates – crudely – into up to $42.5 million in risk each year.  If those 22,000+ homes and other structures had already been there before the levee (concentrated, high-value, and preexisting), then this annual $42.5 million in residual risk would have been a necessary tradeoff.  But because Natomas was a field-of-dreams levee built intentionally to create new floodplain infrastructure, the large majority of this $42.5 million/year is all-new and added risk.

Who bears this residual risk if (some would say “when”) California’s drought turns to flood and hands us a “>200-year flood?”  Or a lesser flood that finds a chink somewhere in the 42-mile long, gopher-prone armor that surrounds Natomas?  Developers and home builders may be gone, but residents of Natomas will be there and are the ones who are rolling the residual-risk dice year after year.  So too are all US taxpayers, since we bankroll disaster relief.  Federal expenditures for disaster relief have averaged ~$35 billion per year in recent years[9], equivalent to about $400 per year per US household.

Residual risk also can be borne by the governmental agencies that facilitate “field of dreams” levees.  Legal liability came to roost in California in 2003, when the Court of Appeals found the state liable for $500 million in damages resulting from a levee break on the Yuba River in February of 1986, the same storms that flooded St. Helena.  The case was Paterno v. State of California, and although the state neither built nor maintained the levee that gave way, the court found that it was responsible for inadequate maintenance and management of the system.  And liability extends to counties and towns as well; for example, California Assembly Bill 80 made local jurisdictions liable for “property damage caused by a flood [if they] … unreasonably approv[e] new development in a previously undeveloped area[10].”  In the Paterno case, the financial hit of that $500 million decision shook the financial structure of the entire state, such that California was forced to borrow funds from Merrill Lynch in order to pay the claims against it[11].

So where does St. Helena and its levee fit into this broader picture?  This levee and the new construction proposed behind it are tiny compared to what has gone onto Sacramento area floodplains, St. Louis floodplains, Houston floodplains, and others.  But the principles are the same, and the potential consequences for a small community like St. Helena are proportionally even more threatening than for a large city.  The St. Helena Vineyard Valley levee was built to protect residents who had the misfortune of living in a neighborhood built on the edge of the Napa River and far into the floodplain, a neighborhood that should not have built in the first place.  That was certainly mistake number one.  But after repeated and devastating floods, those residents were justified in seeking a mitigation solution.  The second crucial misstep occurred in 2009, when the city approved a levee map that enclosed a large area of floodplain empty except for rows of grapevines.  Whether by nefarious purpose or just fatigue, St. Helena opened the door to the crucial and difficult decision now in front of them – whether to bow to the pressure and temptation of approving development of that empty land behind their levee.

vineyard valley levee

Figure 4 – View from Vineyard Valley Levee access road, towards the east, showing current conditions of the proposed development area. Figure IV.A-3a in Hunter Valley Subdivision Project, Draft EIR, Dates 5/29/2012.

One concern certainly on the minds of St. Helena city leaders is the threat of litigation if they deny the development plans in front of them.  When such cases go to court, plaintiff lawyers typically cite the Fifth Amendment of the US Constitution, which states that “private property [shall not] be taken for public use, without just compensation.”  The legal claim is that refusal to allow development of the owner’s land constitutes a “takings” of the value of that land.  The St. Helena situation is typical of many examples where the legal threat of a takings claim is used to thwart zoning or planning to manage flood risk and other natural hazards.  Developers and their lawyers argue that zoning to prevent development is unjustified, arbitrary, and an infringement of the rights of landowners.  On the contrary.  The St. Helena developer purchased agricultural land in a floodplain at a price consistent with those conditions.  Despite the construction of a levee at taxpayer expense surrounding that land, it remains a floodplain.  The limitation on building expensive homes and apartments on that floodplain is imposed by nature, not the City of St. Helena.

Fear of lawsuits and potential liability is a tangible pressure on a town like St. Helena.  But in considering development of floodplain land behind a field-of-dreams levee, these communities are perhaps looking at the lesser threat.  Bowing to the will of the developer dodges a likely “takings” lawsuit, but loads St. Helena with new residual risk – risk that is small as an annual percentage, but large in total magnitude.  The mean value of a detached home is St. Helena is $640,000 and an attached unit is $401,000[12].  Given current plans for 51 new single-family homes, 11 granny units, 24 multi-family units5, and a typical value of 50% content damages for flood-loss estimates, these 87 new units could suffer $49 million in damages if that area were inundated.  After the 1995 flood, residents of Vineyard Valley sued the City, and residents of the proposed new development could take the same action.  The 2003 Paterno decision against California amounted to just 0.5% of the state’s total budget that year.  For comparison, the City of St. Helena, with revenue to its general fund of $10.5 million in FY 2015/16, could face a financial hit totaling 469% of its annual resources.  In other words, the legal liability from the proposed new development could bankrupt the city nearly five times over.

“The legal liability from the proposed new development could bankrupt the city nearly five times over”

St. Helena was founded in the mid-1800s, near enough the Napa River to gain the benefits of that proximity, but up and off the floodplain.  However beginning in the 1970s, the town suffered the same magnetic pull as countless other communities across the US – succumbing to pressures for growth and the attraction of empty land ever closer to the river.  Located deep in the Napa River floodplain, the Vineyard Valley neighborhood was reviewed and approved, reportedly without even discussing the possibility of flooding.  This was an oversight for which residents paid dearly in 1986 and again in 1995.  Mistake followed mistake: land that never should have been developed, an expensive levee that has already sent the town into financial distress and political discord, and a levee map that somehow enclosed much more floodplain land than the neighborhood it was designed to protect.  St. Helena now has a last chance to bring this cascade to an end and avoid construction of 87 new homes behind their field-of-dreams levee.  Floodplain managers, river scientists, and prudent leaders worldwide counsel that levee protection is never absolute, and that even the tallest and strongest wall comes with an inherent residual risk, a small but real possibility that it may fail or be overwhelmed during future floods.  For concentrated and existing floodplain infrastructure, levees can be the right solution, and residual risk preferable to no action at all.  But towns like St. Helena should understand that levee protection brings a range of consequences, including the possibility of multiplying, not diminishing, the long-term risk of damage and potentially even loss of life in their community.

Nicholas Pinter is a professor in the Department of Earth and Planetary Sciences and an affiliate of the Center for Watershed Sciences. This article was developed with assistance from Megan Nguyen, a junior researcher at the Center for Watershed Sciences. 

Further Reading

[1] Report to the St. Helena City Council, Council Meeting of January 26, 2016

[2] City of Napa. 2009.  Hazard Mitigation Plan, 2009 update.

[3] City of St. Helena, 2007.  Project Summary: City of St. Helena Flood Protection and Flood Corridor Restoration Project

[4] e.g., “Enhanced Minimum Plan” dated 7/2003; City of St. Helena Staff Report dated 4/14/2009

[5] Hunter Subdivision Project, Draft EIR, dated 5/29/2012 (Sch: 2012 032048), Available from default/files/Hunter%20Public%20Review%20Draft%20EIR_%20052912.pdf

[6] 2010 Census data; North Natomas + South Natomas.

[7] City of Sacramento, 2015.  Fact Sheet: Next steps for Natomas with a revised flood map, dated 3/24/15.

[8] US Army Corps of Engineers, A. Kirchner, 2010, Road to a Chief’s Report: American River Watershed [Common Features] Project, Natomas Basin, Sacramento and Sutter Counties, California.

[9] Disastrous Spending: Federal Disaster-Relief Expenditures Rise amid More Extreme Weather. Center for American Progress, 2016.

[10] California Senate Judiciary Committee, 2007.  AB 70: Bill Analysis.  Available from _sen_comm.html

[11] Vogel, N., 2005.  A wave of relief after 1986 flood.  Los Angeles Times, Aug. 15, 2005.  (Available from

[12] 2013 data from

Pinter, Nicholas et al. 2016 Modeling residual flood risk behind levees, Upper Mississipi River, USA. Environmental Science & Policy. 58 131-140

Posted in Floodplains, Planning and Management, Uncategorized | Tagged , , | 4 Comments

Instream flows: Five features of effective summer flow strategies

By Ann Willis

As summer begins and stream flows drop throughout California, concerns resurface about whether there’s enough water to support critical ecosystems. Environmental flows have long been a contentious issue, often presented in conflict with existing water use. But there are five key ideas worth remembering as water users and regulators throughout the state consider how best to support environmental objectives during these periods of naturally low stream flows within the framework of existing water laws and desired water use.

  1. Location matters.

Reduced cold water habitat during the summer is a common concern in a state that supports a number of cold water species, including spring-run Chinook and coho salmon. But while warm water or dewatered streams may appear alarming, they can be part of a stream’s natural condition. Smaller, headwater streams are more likely to have cooler water (assuming there’s snowmelt, rainfall runoff, or groundwater-fed springs to wet the channel).

But larger streams, areas that are far downstream from headwater sources or groundwater contributions, or streambeds of porous gravels are naturally warmer or even dewatered during the summer. These seemingly undesirable, intermittent flow conditions play an important role in supporting biodiversity. Providing instream flows to support cold-water species in these areas won’t overcome natural limitations to desirable habitat, and may promote undesirable, non-native species over native ones.

  1. Objective matters.

Instream flows are often proposed as a way to address a regulatory objective, like recovery of a target species. But each species has different needs at different life stages, so clearly identifying the objective for instream flows is important. Is it to reduce or maintain desirable water temperatures? Ensure passage upstream? Improve or sustain physical habitat? Different objectives have different flow and water quality requirements. Knowing what you’re planning for helps identify when, where, how much, and what quality of water is useful – or not.

  1. More water is not (necessarily) better.

When stream flows are reduced by diversions or regional groundwater use, and degraded ecological conditions also exist, it’s logical to conclude that adding water to the stream will resolve those ecological impairments. Except sometimes it doesn’t.

In general, if stream water is already warm, or the contributing sources are warm, adding water will not cool the stream down. But there are other situations where increasing stream flow can help. Studies show that adding water tends to have the greatest benefit when it’s used to address extreme low flow or water quality conditions – in the right location (see #1).

In the Shasta River, habitat conditions for fall-run Chinook improve the most when water is added to the lowest observed seasonal flows, when fish return to the system, but show little to no effect as these flows increase.


Additional streamflow improved available pool habitat in the Shasta River the most when water was added to the lowest baseflows. From Willis et al. (2015)

In an on-going study of oversummering habitat for coho salmon, preliminary results similarly show that additional water tends to have the greatest benefit when water temperature conditions are at their warmest and stream shade has yet to fully develop. But aside from those extreme conditions, adding water provides marginal, if any benefit. These unexpected findings have important implications, most notably that:

  1. Land and water use do not equal ecological degradation.

Over 80% of the Earth’s land is influenced by humans. Agriculture accounts for almost 70% of human water use. Given the extent of our footprint, achieving conservation goals by reserving habitat from human use or eliminating water use is insufficient and infeasible. Large-scale conservation efforts must consider how to create sustainable

A rice farm in the Yolo Bypass near Sacramento. Photo by Carson Jeffres

A rice farm in the Yolo Bypass near Sacramento. Photo by Carson Jeffres

biodiversity within human-dominated landscapes. This is reconciliation ecology.

Studies show that successful reconciliation is possible. In California’s Central Valley, rice farmers cooperate with water managers, scientists, and regulators to provide floodplain habitat on rice fields for juvenile Chinook salmon, creating some of the most successful growing conditions outside of hatcheries.

Photos by Carson Jeffres, UC Davis

Big Springs Creek in 2008, the year before fencing (left), and six months after cattle exclusion. Photos by Carson Jeffres, UC Davis

In the Shasta Valley, The Nature Conservancy demonstrated how to operate a cattle ranch – including diversions for irrigation –  while restoring and sustaining Big Springs Creek, the largest and most robust cold-water stream

Orchards of walnuts (above) and almonds (below) may be viable sites for groundwater recharge, though the potential for water damage to such high-value crops adds risk.

Orchards of walnuts (above) and almonds (below) may be viable sites for groundwater recharge, though the potential for water damage to such high-value crops adds risk. Photo by David Doll

for juvenile coho salmon in the lower Klamath Basin. Researchers are exploring how flooding fields can promote groundwater recharge while maintaining agricultural activities. These projects show the importance of reconciling land and water use with environmental objectives, as well as their potential for success.

So how do you design a management strategy for a stream system that reconciles ecological and water use objectives?

  1. Focus on QQST – Quantity, Quality, Space, and Time – to achieve long-term, viable, multi-objective water use.

Water management frameworks should explicitly recognize that realistic potential exists to support multiple and competing water uses (i.e., “co-equal goals”) when a stream exists in a reconciled state. QQST is a guiding principle to this framework that provides a method to efficiently identify competing water demands and develop flexible solutions.

Conceptual figure

A conceptual diagram of a stream system as it transitions from a baseline state, through a degraded condition, and into recovery with the implementation of interim, transitional, and long-term measures. From Willis et al. (2013)

Using the QQST principle, three types of management strategies can be developed to achieve established co-equal goals: interim (or “emergency”), transitional, and long-term measures.

Each management strategy is implemented depending on the condition of the aquatic ecosystem, which can be defined in various stages of degradation, recovery, or reconciliation.

Recent actions by the State to curtail water restrictions during the California’s severest drought conditions, and then ease water restrictions while implementing long-term policies to sustain California’s water resources (e.g., the Sustainable Groundwater Management Act) are good examples of the various types of interim, transitional, and long-term measures that can be used.

As the concepts of co-equal goals and reconciled ecosystems become more widely applied, approaches like QQST can help guide water users, resource managers, and agencies to effective and sustainable water management strategies.

Ann Willis is a staff researcher with the Center for Watershed Sciences. Her work focuses on management strategies to balance water resources to achieve co-equal goals of human and environmental water use.

Further reading

Willis et al. 2013. Water resources management planning: conceptual framework and case study of the Shasta Basin.

Willis et al. 2015. Instream flows: New tools to quantify water quality conditions for returning adult Chinook salmon. Journal of Water Resources Planning and Management.

UC Davis Center for Watershed Sciences. Nigiri Project: Growing Rice and Salmon on a floodway.

Bachand et al. 2015. Capturing El Nino for the underground. California Waterblog.

Yarnell et al. 2015. Functional flows in modified riverscapes: hydrographs, habitats and opportunities. Bioscience.

Allan JD and Castillo MM. 2007. Stream Ecology.

Rosenzweig ML. 2003. Reconciliation ecology and the future of species diversity

Sanderson et al. 2002. The human footprint and the last of the wild

Cosgrove and Rijsberman. 2014. World water vision: making water everybody’s business

Posted in California Water, Conservation, Planning and Management, reconciliation, Sustainability | Tagged | 2 Comments

How bad is water management in California?

by Jay Lund

California’s combination of climate, native ecosystems, and human uses makes water management inherently hard, unsatisfactory, and evolving.  California is doomed to have difficult and controversial water problems. No matter how successful we are.

California is one of the few parts of the world with a Mediterranean climate (Figure 1).  These climates tend to be dry (not much water), attractive places to live and farm (bringing high water demands), with mismatch between wetter winters and dry summer growing seasons.  The scarce water supply in the wrong season for human activities makes human management of water problematic for native ecosystems.

Mediterranean climates are special places, socially, economically, and environmentally with unavoidably challenging water problems.

California’s ongoing drought has provided opportunities to scrutinize its water management.  Droughts are trials that help identify problems and solutions.  The current drought has prompted several water management innovations in California, including state efforts to require local groundwater management, tightening water rights administration, and increases in water prices and urban water conservation.  Every drought is different, affecting a somewhat changed water system which serves a changing society, economy, and ecosystem.  Droughts historically catalyze strategic changes in California’s water management system.

If California is doomed to have hard water problems and unsatisfactory water solutions, how is California doing relative to other parts of the world blessed and burdened with Mediterranean climates.  Table 1 roughly compares the world’s regions with Mediterranean climates in terms of the population they support, economic wealth per capita, size of their agricultural economy, and (very roughly) condition of their native freshwater aquatic ecosystems.

As a person, native fish, or farmer, in which Mediterranean climate would you rather live?

Table 1. Comparison of Water Management Success for the World’s Mediterranean Climates (Population and economic data from  Agricultural economy data from FAO Statistical Pocketbook 2015. Ecosystem assessment is purely subjective.)

Country/ State Population (millions) Wealth (GDP PPP/person) Food Production ($ billion) Native Freshwater Aquatic Ecosystem Condition
California 39 $62,000 $45 Struggling, much diminished
Algeria 39 $13,000 $8 Largely eliminated
Australia 24 $68,000 $25 Substantially eliminated
Chile 18 $22,500 $8 Substantially eliminated
Greece 11 $26,000 $6 Largely eliminated
Israel 8 $36,000 $3 Largely eliminated
Italy 61 $35,600 $29 Largely eliminated
Morocco 33 $7,000 $9 Largely eliminated
S. Africa 54 $12,500 $13 Struggling, much diminished
Spain 46 $43,000 $32 Largely eliminated

California is perhaps the world’s best-performing region with a Mediterranean climate in terms of managing water for both humans and ecosystems.  California can learn from other regions, but is certainly not a laggard in terms of environmental and economic performance among Mediterranean climates.  We do not do as well with water as we would like, and we must find ways to do better, but California nevertheless does relatively well in managing water.

This is not to encourage complacence, but to discourage panic.  There seems little reason to support an overall revolution in most of California water management, despite ongoing needs to make substantial improvements.  California always will need to pay attention to making improvements in how water is managed, to reduce the inherent dissatisfactions of a populous, prosperous, and agriculturally productive region with a dry Mediterranean climate.  Organized and persistent attention with high but realistic expectations has been key to California’s historical success and to continued change and progress.

Further readings

Alexander, B.S., G.H. Mendell, and G. Davidson (1874), Report of the Board of Commissioners on the Irrigation of the San Joaquin, Tulare, and Sacramento Valleys of the State of California, Washington: G.P.O., 1874.

Bonada, N. and V.H. Resh (2013) “Mediterranean-climate streams and rivers: geographically separated but ecologically comparable freshwater systems,” Hydrobiologia, Volume 719, Issue 1, pp 1-29.

Gasith, A. and V. H. Resh (1999), “Streams in Mediterranean Climate Regions: Abiotic Influences and Biotic Responses to Predictable Seasonal Events,” Annual Review of Ecology and Systematics, Vol. 30: 51-81 (Volume publication date November 1999), DOI: 10.1146/annurev.ecolsys.30.1.51

Hanak, E., J. Mount, C. Chappelle, J. Lund, J. Medellín-Azuara, P. Moyle, N. Seavy (2015), What If California’s Drought Continues?, Public Policy Institute of California, San Francisco, CA, August 19, 2015

Lund, J. California droughts precipitate innovation 21 January 2014,

Mount, J., B. Gray, C. Chappelle, J. Doolan, T. Grantham, and N. Seavy (2016) Managing Water for the Environment During Drought: Lessons from Victoria, Australia, PPIC, San Francisco, CA, June.

Pisani, D. 1984. From the Family Farm to Agribusiness: The Irrigation Crusade in California, 1850–1931. Berkeley: University of California Press.

Underwood, E.C. , J. H. Viers,  K.R., Klausmeyer, R. L. Cox, and M. R. Shaw (2009), “Threats and biodiversity in the mediterranean biome,” Diversity and Distributions, (Diversity Distrib.) (2009) 15, 188–197

Posted in Drought, Planning and Management | Tagged | 11 Comments

California Water Made Simple

California_water_explained_2dCelebrating end of the academic year, and the need to grade papers, here is a reprise post from January 29, 2014.

There’s only so many acre-feet of water jargon the public can absorb during a drought. Here’s a primer that avoids wading into cubic-feet-per-second, appropriative water rights, overdraft, conjunctive water use and the like.

Further reading

Hanak, et al. 2011, Managing California’s Water: From Conflict to Reconciliation, Public Policy Institute of California

Posted in Uncategorized | 3 Comments

Trump’s Dubious Drought Claims

By Vanessa Schipani

This post originally appeared on June 9, 2016 on The original post can be found here. Peter Moyle, Associate Director at the UC Davis Center for Watershed Sciences, and Jeffrey Mount, Senior Fellow at the Public Policy Institute of California and founding director of CWS, dispel some myths in Trump’s Fresno rally speech.

During a campaign rally in Fresno, Donald Trump made two misleading claims about California’s drought and water issues:

  • Trump suggested “there is no drought” in California because the state has “plenty of water.” But California is in its fifth year of a severe “hot” drought, the kind that’s expected to become more frequent with global warming.
  • He also said water is being shoved “out to sea” to protect a “three-inch fish” at the expense of farmers. But officials release fresh water from reservoirs primarily to prevent salt water from contaminating agricultural and urban water supplies.

On May 27, Trump met with farmers for a private half-hour meeting before his rally in Fresno, as reported by the Los Angeles Times. During his speech, Trump references this meeting, stating, “I just left 50 or 60 farmers in the back and they can’t get water. And I say, ‘How tough is it? How bad is the drought?’ ‘There is no drought. They turn the water out into the ocean.’” Earlier in this speech, he made similar claims:

Trump, May 27: You have a water problem that is so insane. It is so ridiculous, where they’re taking the water and shoving it out to sea. And I just met with a lot of the farmers, who are great people, and they’re saying, “We don’t even understand it” … I’ve heard it from other friends of mine in California, where they have farms up here and they don’t get water. And I said, “Oh that’s too bad. Is there a drought?” “No, we have plenty of water.” I said, “What’s wrong?” “Well, we shove it out to sea.” And I said, “Why?” And nobody even knows why. And the environmentalists don’t know why. Now, they’re trying to protect a certain kind of three-inch fish.

Trump also told his audience in Fresno that if he wins the election, “Believe me, we’re going to start opening up the water, so that you can have your farmers survive.” He added, “We’re going to get it done quick. Don’t even think about it. That’s an easy one.”

SciCHECKsquare_4-e1430162915812According to the New York Times, Trump is right that some farmers believe the preservation of fish species has caused the state’s water issues. In June 2015, the newspaper reported that, “Farmers in the Central Valley call it a ‘man-made drought,’ complaining that water needed for crops is going to fish instead.” Carly Fiorina, previously Hewlett-Packard’s CEO and a GOP candidate, also made similar claims when she was considering running for president last year.

But California’s water issues can’t be reduced to the preservation of a threatened fish species. Experts told us water management practices, the state’s natural climate and global warming have all contributed to the state’s current drought and water issues.

California’s De Facto Drought 

California’s current drought began in late 2011. By Jan. 17, 2014, Gov. Jerry Brown declared the drought a state of emergency.

California’s current drought has meteorological, hydrologic and agricultural elements.  The U.S. Geological Survey calls the dry conditions that often develop after below average amounts of precipitation a “meteorological drought.” These conditions can then cause a “hydrologic drought,” where the flows and levels of streams, rivers, lakes and reservoirs decline. Drought also affects farmers by reducing soil moisture, hindering crop growth, which the USGS calls an “agricultural drought.”

Most of California’s precipitation falls between October and April. As a result, the state’s ecosystems are accustomed to seasonal drought outside of those months. Droughts lasting multiple years are also a regular characteristic of California’s climate.

However, California’s current drought is “unique” when compared with past years, write Jeffery Mount and others at the Public Policy Institute of California in an August 2015 report called, “What If California’s Drought Continues?

“Taken together, the past four years have been the driest since record keeping began in the late 1800s,” writes Mount, a watershed scientist, and colleagues. In other words, the state has experienced the low levels of precipitation characteristic of a meteorological drought.

But the current drought is especially different because 2015 and 2014 were also the two warmest years on record in the state (and it’s likely globally as well). Scientists call the combination of dry and hot conditions a “hot” drought.

Record heat contributed to California’s current meteorological drought, in part, by reducing snowpack in the Sierra Nevada mountains. During the dry season (May to September), this snowpack melts and provides about one-third of the state’s farms and cities with fresh water.

On April 1, 2015, California’s Department of Water Resources estimated the snowpack of the Sierras to be at 5 percent of the average for that time of year – lower than any year in records since 1950. And this is a period when snowpack is supposed to be at its peak.

In addition to receiving less precipitation during winter, warmer temperatures caused what snow had accumulated “to melt faster and earlier, making it more difficult to store and use,” according to California’s water resources department.

While El Niño did bring more precipitation during the following winter (2015 to 2016), and thus more snowpack, it wasn’t enough to end the drought. El Niño changes global atmospheric circulation such that some regions receive more rainfall and others less.

With less precipitation and less water from snowpack, the flow and level of ground and surface water reservoirs also declined in the state, leading to a hydrologic drought.

And with less water in reservoirs, there’s less water for urban and agricultural use. Not to mention that record heat in California also dried up soils and stressed crops, which, in turn, led to a greater need for irrigation (i.e. an agricultural drought).

Mount and his colleagues call California’s current drought a “drought of the future” because the state is more likely to experience such conditions as the region’s climate warms in the coming decades.

“The drought revealed our weaknesses in how we manage water for all sectors,” Mount told us in an email.  “It gave us an unwelcome … glimpse into the future as conditions warm in California and competition for water becomes more intense.”

In short, California’s drought is very real and the state does not have “plenty of water,” as Trump suggested. California’s water issues go far beyond preserving a “three-inch fish,” as we’ll explain in the next section.

Water Wars

Water management practices, along with the drought, have contributed to difficulties for farmers in parts of California.

To start, not only does California receive the majority of its precipitation between October and April, but it also primarily rains and snows in the northern parts of the state.

This creates a water management “problem” because most of the demand is from farms in the San Joaquin Valley and coastal urban areas, such as Los Angeles, Peter Moyle, a fish biologist and associate director of the Center for Watershed Sciences at the University of California, Davis, told us in an email.

The San Joaquin Valley makes up the southern two-thirds of California’s Central Valley. The northern one-third is known as the Sacramento Valley. The San Joaquin Valley is divided into the San Joaquin Basin and the Tulare Basin. Fresno, where Trump gave his speech, lies in the Tulare Basin, the southernmost section of the Central Valley.

“Massive water projects … have turned essentially desert areas into places where people can live and farm,” Moyle told us.

As the New York Times reported, these projects include giant pumps that transport water from the Sacramento-San Joaquin Delta to the Central Valley and to cities in southern California, such as Los Angeles. The water flowing into the Delta originally comes from farther north, including from the Sierra Nevada mountains.

However, “During long droughts there is a natural tendency to keep in the north the water that has been produced there, assisted by very old and sacred water rights,” Moyle told us. “Many farmers in the south not only have a very limited indigenous supply of water, but they have very junior water rights to use both local rivers and imported water.”

This creates competition for water between northern and southern farmers, but also exacerbates issues between Central Valley farmers and environmentalists, Moyle said.

With less water in general due to drought and fewer rights to the water that is available, Central Valley farmers argue the current drought is man-made because water is being “wasted to the ocean” to preserve fish species, Moyle added.

So how is available water actually distributed in California? Back in July 2014, Mount and colleagues at the Public Policy Institute of California broke down water use in the state into three sectors: 50 percent environmental, 40 percent agricultural and 10 percent urban.

But “environmental” water usage is only partly used for preserving fish species, such as the delta smelt and Chinook salmon.

For one, “More than half of California’s environmental water use occurs in rivers along the state’s north coast,” write Mount and colleagues. Farmers in the Central Valley and elsewhere can’t access most of this water because it’s largely isolated from the state’s water management infrastructure (i.e., the Delta pumps).

Many of the rivers of northern California are designated as wild and scenic, which means they can’t be dammed without an act of Congress. In a blog post, Mount writes, “Most of the volume that flows down Wild and Scenic Rivers is in the North Coast and includes flood flows, where there is no practical way to recover it for either agricultural or urban use.”

In areas where water is shared by all three sectors, agricultural use dominates at 53 percent, compared to 33 percent environmental use and 14 percent urban use, according to Mount and his colleagues.

Even still, some environmental water use benefits farmers, as it’s needed to maintain water quality for agricultural and urban use.

How so? As previously mentioned, the current drought has reduced surface water levels and flows, which left the Sacramento-San Joaquin Delta more susceptible to salt water intrusion from the ocean. And when salt water infiltrates fresh water supplies, it can’t be used for urban and agricultural purposes.

To solve this problem, officials release water from reservoirs to prevent salt water from contaminating fresh water in the Delta.

Reservoir water also needs to be released because the state’s water infrastructure itself, which directs water north to south, disrupts the Delta’s natural ability to flush salt water out to sea (an east to west flow), Mount told us.

But these releases also help keep the Delta’s water fresh for threatened species, such as the delta smelt. The state is mandated by law to protect this fish, the Chinook salmon and other species under the Endangered Species Act.

During his rally, Trump was most likely speaking about the delta smelt when he referred to a “certain kind of three-inch fish.” We reached out to Trump’s campaign for clarification, but have yet to hear back.

The Chinook salmon “has equal or greater impact on water supplies” compared to the delta smelt, Mount also told us. “The reason is that salmon do not just need flow, but they need cold water.”

The state’s water infrastructure, which includes dams in addition to pumps, has “cut off more than 85% of the historic spawning habitat for salmon,” primarily in the Central Valley, added Mount.

To make up for the loss of spawning habitat, “we have to reserve cold water, which collects at the bottom of reservoirs, to release for salmon, particularly winter- and spring-run Chinook which are teetering on the brink of extinction,” said Mount. “This causes a delay in the release of water until late in the irrigation season, which directly impacts supplies to farms.”

However, Mount and colleagues estimated that in 2014, 71 percent of “ocean outflow,” or released fresh water from reservoirs, was needed for urban and farm water salinity control, while 18 percent was required to preserve fish habitat.

So despite what the Fresno farmers may have told Trump, California’s water issues go far beyond protecting “a certain kind of three-inch fish.”

First, delta smelt are not the only fish that require preservation. Chinook salmon and other species also benefit from the release of fresh water from reservoirs. Second, most of the water that is being flushed out to sea is needed to prevent salt water from infiltrating agricultural and urban water supplies. And lastly, the infrastructure that was developed to deliver water to farmers in the Central Valley has itself disrupted the Delta’s natural ability to flush salt water out to sea, contributing to the need to release fresh water from reservoirs.

Overall, it’s unlikely the solution to California’s water wars will be “quick” and “easy,” as Trump said.  “Water management issues are never black and white,” Mount told us.

Editor’s Note: SciCheck is made possible by a grant from the Stanton Foundation.

Clarification, June 9: We changed Peter Moyle’s title from “wildlife ecologist” to “fish biologist”  at the request of UC Davis.

Vanessa Schipani is a Science Writer at


Posted in California Water, Delta, Delta Smelt, Drought, Fish, Salmon, Uncategorized | Tagged , , | 5 Comments

Cue the Frogs! Water signatures, environmental cues and climate change

FYLF Lay egg

Figure 1: A female foothill yellow-legged frog (Rana boylii) waiting to lay eggs (gravid).

By Ryan Peek, Helen Dahlke, and Sarah Yarnell

An organism’s success relies on responding to environmental cues that trigger activities such as breeding, migration, feeding, predator evasion, etc. Responses can be finely tuned to specific cues, or may require multiple triggers. For example, changes in day length and air temperature cue many bird migrations over thousands of miles between breeding and wintering grounds. Some catfish species spawn immediately after heavy rains, sensing the increase in water levels and decreases in water temperature. Mosquitoes can smell increased carbon dioxide levels from mammals as far as 50m away and use these “invisible plumes” to guide them towards food. In dynamic environments like rivers, environmental cues may help organisms forecast stable conditions suitable for activities such as laying eggs or rearing larvae, especially if these cues reliably indicate good conditions.

Human activities can disrupt or eliminate environmental cues that keep species successful. A recent example is endocrine disrupting chemicals which can block or disrupt hormones needed for breeding, migration, feeding (Wingfield and Mukai 2009, Rogers et al. 2013, Kabir et al. 2015). In many species, we only have some understanding of environmental cues and what disrupts them. Better understanding cues can help managers implement restoration and protection actions.

We have been exploring environmental cues for the foothill yellow-legged frog [FYLF] (Rana boylii) in rivers in the Sierra Nevada. Significant work has identified suitable breeding and rearing habitat conditions for these river-breeding frogs, which have adapted to California’s seasons and are genetically wired to lay eggs during the spring snowmelt when river flows recede and water temperatures increase.

FYLF Breeding

Figure 2:  Foothill yellow-legged frog breeding timing over three years in the North Fork American River.

How do frogs detect this cue in flow patterns? Frogs can detect fine changes in the nutrients in the water, or more specifically, compounds like potassium and sodium. Streamflows have different chemical signatures depending on their water source. Snowmelt, groundwater, and rainwater have different chemical signatures. With climate warming, there will be less snow, more rain, more frequent high intensity storms, and longer periods of low flows. This may be important for species which use environmental cues based on water chemistry to trigger breeding. As these cues shift in the future, understanding which specific cue is driving the response (breeding) will important for managing rivers in the Sierra Nevada.

We’ve been monitoring foothill yellow-legged frog populations in Sierra rivers since 2011. To determine how water chemistry might be a breeding cue, we examined daily water samples along the North Yuba River during spring of 2014. These samples were analyzed for isotopes of oxygen and hydrogen to determine the water source. Isotopes in water samples can reveal the shares of snowmelt, rainfall, and groundwater in streamflow. Preliminary results indicate that the frogs didn’t begin breeding until after the water was completely groundwater driven, when the proportion of rain and snow isotopes were zero. Using a water chemistry cue that links to California’s seasons (i.e., wet winters=rain and snow, dry summers=little rain or snow, just groundwater) would reliably allow organisms to focus on stable hydrology periods, even though these times can shift from year to year with droughts, El Nino, etc. By cueing to the beginning of the low flow period, frogs (and other species) may reduce the risk of breeding during storm events or during unstable flow periods that can scour egg masses from rocks, or strand and dry egg masses.

Breeding was only seen in the mainstem North Yuba (green line in plots below). Pauley Creek and Haypress Creek (the blue and pink respectively) were likely too cold for frogs to successfully breed and develop over the summer, but these sites illustrate important elevational gradients in source water (See Plots).

FYLF temp

Figure 3: Hourly water temperatures in 3 study sites in the North Yuba watershed. FYLF breeding was only observed at mainstem North Yuba site (green).

FYLF storm

Figure 4: Proportion of storm event water that was rain vs. groundwater at three sites in North Yuba. Average daily stage plotted for each site (dashed line).

Isotope analysis has helped us understand water sources for assessing food web connectivity and species. Our new work shows that water chemistry cues seem particularly effective for frogs, particularly FYLF, in Sierra streams. Understanding these cues may help in developing more effective flow releases below dams or other actions that support needed flow, chemical, or temperature cues.

We continue to monitor our long term sites and collect additional water samples at some sites to further assess how water chemistry may act as a breeding cue for these sensitive amphibians in regulated and unregulated systems.

Further Reading

Foothill yellow-legged frogs. Ecology, river regulation, and conservation. Pacific Southwest Research Station, USFS.

Kabir, E.R., M.S. Rahman, I. Rahman. 2015. A review on endocrine disruptors and their possible impacts on human health. Environmental Toxicology and Pharmacology. Vol. 40 (1), 241-258.

Peek, R., H. Dahlke, S. Yarnell. 2016. Linking water source signatures with native amphibian breeding timing in a Northern Sierra Nevada watershed. Hydroecology C10. Presentation for Annual Meeting at Society for Freshwater Science, Sacramento CA.

Rogers, J.A., L. Metz, V. W. Yong. 2013. Review: Endocrine disrupting chemicals and immune responses: A focus on bisphenol-A and its potential mechanisms. Molecular Immunology. Vol 53 (4) 421-430.

Wingfield, J. C. and M. Mukai (2009). Endocrine disruption in the context of life cycles: perception and transduction of environmental cues. General and Comparative Endocrinology 163(1-2): 92-96.

van Breugel, F., J. Riffell, A. Fairhall and M.H. Dickinson (2015). Mosquitoes Use Vision to Associate Odor Plumes with Thermal Targets. Current Biology 25(16):2123-2129.

Yarnell S.M., R.A. Peek, D.E. Rheinheimer, A.J. Lind, J.H. Viers. 2013. Management of the Snowmelt Recession. 137.

Posted in Conservation, Stressors, Uncategorized | Tagged , , , | 1 Comment

Water and salt exports from the Delta – A tale of two plots

By Jay Lund and William Fleenor

Where does water exported from the Delta come from?  And where does the salt in Delta exports come from?

Water and salt exported from the Delta comes from several sources:

  • Sacramento River (largest high-quality source) (Sac)
  • San Joaquin River discharge (usually modest flow, but much saltier from agricultural drainage) (SJR)
  • smaller eastside streams (Mokelumne River, etc.; usually small, but good quality) (East)
  • Delta drainage water and precipitation (lower quality) (Delta)
  • Ocean water (salty, mixed in by tidal action, if above sources are inadequate) (Martinez).

Here are some answers in two plots, routinely produced by the California Department of Water Resources (DWR), showing estimates of the mix of these sources in southern Delta water exports.  These are for State Water Project (SWP) exports so far in 2016.  (The tidally-averaged estimates are made using DWR’s DSM2 model.)

Where does your water come from?

For 2016, so far, most of the water exported by the SWP from the southern Delta is actually Sacramento River (Sac) water which has been hydraulically dragged through the Delta.  The San Joaquin River (SJR) contributes some, and the Eastern streams (East) a bit as well.  “Delta” (Delta) water is also present, as is ocean water (Martinez) just a little in January.


Sources of water exported by State Water Project at Clifton Court in southern Delta, January-May 2016

Where does your salt come from?

The salinity in SWP exports varies with both the quantity and quality of each water source.  In January, the little bit of salty ocean (Martinez) water is a disproportionate contributor of salt to urban and agricultural diversions in the southern Delta.  The fairly low Delta water quality is also seen, disproportionate from its more modest quantity of diversion.  The Sacramento River, which is 60-80% of the water diverted, only contributes a third of the salt.  Note also the extra salinity of the lower San Joaquin River.

Note also that the field data on salinity at the SWP diversion is a bit higher that what the model estimates.  So there is some model error in this case, probably mostly from errors in the ocean boundary conditions and estimated in-Delta consumptive use.

Figure 2

Sources of salinity in water exported by State Water Project at Clifton Court in southern Delta, January-May 2016, salinity as electrical conductivity. Dots are field data, Colored areas are model results

What does a wet year look like?

2011 was the most recent wet year, with the last quarter of 2011 shown in the figures below.  The mix of sources was very different.  The Sacramento River remained the dominant source, with much more from the San Joaquin River (with better-than-usual water quality), less Delta water, and some eastern streamflow.


Sources of water exported by State Water Project at Clifton Court in southern Delta, September-December 2011 (wet year)

Salinity was much better, until the end of the year when a bit of ocean (Martinez) water intruded.  The San Joaquin River contributed to salinity disproportionately as well.  The model fit the field data much better.


Sources of salinity in water exported by State Water Project at Clifton Court in southern Delta, September-December 2011 (wet year), salinity as electrical conductivity. Dots are field data, Colors are model results

The Delta is a complex and changing place.  Its waters also change in quality and quantity with the tides, seasons, and years.

The authors are with the Center for Watershed Sciences, University of California – Davis.

Further reading

California Department of Water Resources, Delta water fingerprinting archive, 2005-2016,  This is a rich and thought-provoking set of field observations and modeling results.

Fleenor, W., E. Hanak, J. Lund, and J. Mount, “Delta Hydrodynamics and Water Quality with Future Conditions,” Appendix C to Comparing Futures for the Sacramento-San Joaquin Delta, Public Policy Institute of California, San Francisco, CA, July 2008.

Medellin-Azuara, J., E. Hanak, R.E. Howitt, Fleenor, W.E., and J.R. Lund, “Agricultural Losses from Salinity in California’s Sacramento-San Joaquin Delta,” San Francisco Estuary and Watershed Science, Vol. 12, No. 1, 2014.

Posted in California Water, Delta, Uncategorized | Tagged , | 3 Comments

Understanding predation impacts on Delta native fishes


Native threespine sticklebacks pumped from the stomach of a single 22 inch striped bass. The bass was feeding in water being drained from a duck club in Suisun Marsh, The sticklebacks were abundant, concentrated, and confused so were easy prey for the bass. Sticklebacks continue to be one of the most abundant fish in Suisun Marsh. Photos by Teejay O’Rear April 2010.

By Peter Moyle, Andrew Sih, Anna Steel, Carson Jeffres, William Bennett of University of California, Davis.

Will endangered fishes, such as Chinook salmon, delta smelt, and longfin smelt, benefit from control of predators, especially of striped bass? This question is of interest because if the answer is ‘yes’, then predator control might increase the benefits of other actions, such as provision of environmental water for native species. In this blog we express our skepticism of large-scale predator control as a conservation tool, based on eight principles.

  1. Predation ‘problems’ do not have simple solutions.
    Predation is one of many stressors affecting declining species. In ecosystems such as the Delta, predator-prey relationships are complex. Many predators forage opportunistically on whatever prey species are most abundant and accessible at any time and place. As a result, predator control can have unintended consequences.  For example, reducing striped bass populations might cause an increase in important prey species, such as Mississippi silverside, that prey on delta smelt eggs and larvae. In other words, controlling striped bass may backfire and increase predation on delta smelt.  Grossman et al. (2013) have written a good overview of predator-prey dynamics in the Sacramento River. This review provides a basis for the above statements and the conclusion that predator control in the Delta will likely create more problems than it solves. This conclusion can be applied broadly to predator control programs, such as those for invasive mammals.  However, more research could provide a better understanding of predation as a stressor of fish populations, provided that such studies are linked with modeling, focusing on predator-prey interactions in the Delta (similar to work done for the lower Columbia River).
  1. The best long-term strategy for increasing populations of small fish (prey) is to improve the ability of the ecosystem to support them.
    In a healthy ecosystem, multiple predators and multiple prey typically co-exist in dynamic fashion. Prey species such as delta smelt have highly effective predation defense mechanisms that operate best in an environment similar to the one in which they evolved. For the Delta, we suggest that ecosystem recovery efforts should focus on the arc of habitat that includes the Yolo Bypass, the Lindsey-Cache slough region, the Cosumnes-Mokelumne river region, the Sacramento River, Sherman Island and Suisun Marsh (similar to the String of Pearls concept for Chesapeake Bay).  This region is tied together (the string) by the interaction of Sacramento River flows with tidal flows and contains the highest concentrations of native fishes in the upper estuary.
  1. Bypassing problem areas can reduce predation impacts.
    Increasing flows from the Sacramento River down the Yolo Bypass in winter could carry large number of juvenile salmon from upstream areas to productive habitat in the Yolo Bypass. Such flows can also attract fishes such as splittail, and perhaps smelt from the Delta into the Bypass. Fish using the Bypass avoid the rip-rapped channels and likely high predation areas in the western Delta and lower Sacramento River. A similar strategy might work for the San Joaquin River and southern Delta if fish (except smelt) were directed towards the pumping plants and then trucked past predation hot spots in the Delta.  This strategy will only work if predation on trucked fish is reduced by modifying the pumping facilities and adopting different release strategies (#4, #5).
  1. Changing release strategies of captive fish can reduce predation mortality.
    Salmon and other fishes are most vulnerable to predation when they are transported to a release site, usually by truck, and then dumped into the water in large numbers in one place. This release strategy, used by the pumping plants in the South Delta and by many hatcheries, caters to predator behavior, because predators are attracted to concentrations of prey, especially prey that are confused following release. Release strategies need to be developed and carefully monitored, such as slow releases from barges towed at random times of day and night, which do not habituate predators to concentrations of prey. Similar release strategies are needed for hatchery salmon releases as well (#8).
  1. The solution to reducing effects of predation ‘hot spots’ is to move prey around them (see #3) or to reduce their attractiveness to predators.
    Predatory fishes such as striped bass move around a lot.  Therefore, predator control on a hot spot has to be continuous and intensive, because as predators are removed new ones are likely to move in.  However, each hotspot has its own problems that have to be dealt with individually.  For example, Sabal et al. (2016) found striped bass consumed 8-29% of juvenile salmon passing through Woodbridge Irrigation District Dam on the Mokelumne River and reducing the numbers of adult striped bass could temporarily reduce predation rates. It helped that the ‘hot spot’ was some distance upstream from the Delta, where most bass reside. Their conclusion was not that universal striped bass control was needed but that “ …it is important to consider habitat alterations and interactive effects when estimating large-scale predation impacts and when planning local management strategies (p 318).”This conclusion applies to Clifton Court Forebay, which is well-documented as one of the hottest of the predation hotspots.  Striped bass and other predators concentrate there to feed on small fish drawn towards the giant pumps at the state pumping plant. Modifying its structure or operation should be the best way to reduce predation impacts in the forebay. In this light, the National Marine Fisheries Service is currently requiring that both long-term and interim measures to reduce predation on endangered fishes be implemented (letter from Maria Rea to Carl Torgersen, January 22, 2016).  Essentially, NMFS is saying that just studying the problem is no longer a sufficient response to the documented high predation rates at this facility.
  1. Striped bass are not the problem.
    Striped bass get blamed for declines of native fishes because they are an abundant, voracious, non-native predator. Yet striped bass have been part of the Delta ecosystem for nearly 150 years, plenty of time for co-adaptation of predator and prey.  In periods when delta smelt, longfin smelt, and salmon were abundant in the past, striped bass were much more abundant than they are today, suggesting that the same factors that drive native fish declines are also driving striped bass populations.  As generalist, wide-roaming predators, they feed on the most abundant prey available, which is often the result of ‘ringing the dinner bell’ release strategies of captive fish (see #4, above). If striped bass regulate populations of any other fishes, their effects will be mostly on small, consistently abundant prey fishes such as Mississippi silverside and threadfin shad that may compete with or prey on smelt and juvenile salmon.  By reducing competition or predation by silversides or shad on smelt, striped bass might actually have a net positive effect on smelt.  Indeed, other managers have found, to their distress, that reducing top predators has backfired because of this ‘enemy of my enemy is my friend’ effect.  Repeating this error in our system would be unfortunate. All this indicates that programs aimed at direct striped bass control are as likely to have no or negative effects, as to have positive effects, on populations of desirable fishes.
  1. Having a prey species in a predator’s diet does not mean the predator controls the prey’s populations.
    Dietary studies of predators in the Delta have often concentrated in areas where predation is perceived to be a problem, such as predation by striped bass near water diversion structures on salmon in the Delta and Sacramento River or below hatchery release sites. It is not surprising that prey are seen in predator stomachs in those situations. Prey fish have evolved strategies to minimize the effect of predators. For example, a natural predation-reduction strategy of juvenile salmon is to migrate to the ocean in pulses, usually when river flows are high and muddy from run-off. Striped bass and other predators might have stomachs full of juvenile salmon at this time but the percentage of total population is likely to be low. Granted, such strategies may no longer be fully effective under conditions of drought, warm winters and reduced population sizes; however, reduction of overall striped bass predation will likely increase predation by other organisms, taking advantage of whatever increase in prey the absence of striped bass might cause.. In short, a predator control program based mainly on dietary studies is too simplistic to serve as a basis for management to increase prey populations.
  1. Hatchery-reared salmon are exceptionally vulnerable to predation.
    Hatchery salmon start life packed together in cement troughs, with food pellets raining down from above.  This does not give the fish much chance to learn how to avoid predators. They are then either released directly into a river or trucked to a release point in the estuary.  It is scarcely surprising that predators take advantage of these naïve and fat-laden prey, gorging themselves.  Many of these salmon die of stress and other causes. They are then scavenged by unlikely predators such as white catfish.  Studies on the Yolo Bypass indicate that about 30% of hatchery salmon die within a day or two after release into food rich, nearly predator-free environments, in which most wild salmon thrive (Jacob Katz, unpublished data).   Release of hatchery fish into rivers in large numbers mimics, to a certain extent, the predator-swamping strategy used by wild fish.  But the rivers are rarely high and muddy during the release and the fish lack the behavior to avoid predation in clearer water, so predation rates are high.  In short, heavy predation on juvenile hatchery salmon is more a reflection of hatchery practices than of un-natural rates of predation by striped bass and other predators.

Conclusion.  It seems unlikely that a large-scale predator removal program focused on striped bass would have a sustainable, measurable effect on populations of its prey species, specifically protected smelts and salmon. However, if managers deem enough uncertainty exists about the importance of predation as a source of mortality relative to other factors, then an integrated program of empirical studies and modeling should be instituted.   If a control program moves forward despite scientific uncertainty, it should be implemented as an experiment, focusing on data collection and modeling to determine if the program achieves carefully specified objectives.

Further reading

Cannon, T. 2016. Hatcheries Release Salmon Smolts into Low Flows and Warm Water – April and early May, 2016. California Fisheries Blog. May 5, 2016.

Doherty, T.S. and E. G .Richie. 2016.  Stop jumping the gun: a call for evidence-based invasive predator management, Conservation Letters. doi: 10.1111/conl.12251.

Grossman, G., Essington, T., Johnson, B., Miller, J., Monsen, N. and T. Pearsons. 2013. Effects of fish predation on salmonids in the Sacramento River – San Joaquin Delta and associated ecosystems. Report for Cal. Fish Wildlife/Delta Stewardship Council/NMFS. 71pp.

Moyle, P B.   2011. Striped bass control: cure worse than disease?

Sabal, M., S. Hayes, J. Merz, and J. Setka. 2016  Habitat alterations and a nonnative predator, the striped bass, increase native Chinook salmon mortality in the Central Valley, California. North American Journal of Fisheries Management 36:309–320. DOI: 10.1080/02755947.2015.1121938

Sabalow,R. 2016. Should California’s striped bass be vilified as native-fish killers? Sacramento Bee May 6, 2016.

Wunderlich, V. 2015.  Clifton Court Forebay Predation Study.  Bay-Delta Office, California Department of Water Resources.

Posted in Delta, Fish | Tagged , , , , | 2 Comments

SGMA and the Challenge of Groundwater Management Sustainability

By Bill Blomquist

It isn’t just the groundwater that has to be sustainable; it’s the management too.

That’s why the title of this post shifts from the more familiar “sustainable groundwater management” to “groundwater management sustainability.” This perspective doesn’t come from the world of hydrologic or climate or environmental science, but from political science and other disciplines focused on human institutions and behavior.

Along with the development and use of information, the greatest challenge in groundwater sustainability is governance and decision making. Over several decades we have learned that governance is at least as important in environmental management and protection as are science and data. That’s saying a lot, because science and data are critical. Understanding institutions for governing human interactions with the environment and with other humans is at that critical level or greater.

The challenge of governance and decision-making involves dealing with scales and levels, the legal and regulatory framework, and multiple publics and values; also, supporting and institutionalizing innovation, adaptation, and learning. Plainly this is complicated, and like the challenge of information, it is unlikely to be solved once and for all.

The treatment of institutions in policy analysis versus political science

Institutions come up a lot in policy discussions. Policy discussions generally follow this form: “What should we do about X?” Fill in the “X” with the relevant policy topic—groundwater sustainability, mass transit, international terrorism, etc.—and the policy discussion ensues, with varying voices and perspectives advocating one solution or another.

Institutions generally appear in these kinds of policy discussions as prescriptions. They are advocated for their predicted beneficial effects in remedying the illness – the “X” — that’s under discussion.

Got a groundwater problem? Take some private property rights plus a market and call me in the morning, or take a public trust doctrine plus a regulatory agency, or take a comprehensive watershed management authority, or take a public participation process plus some citizen science… etc.

These institutional prescriptions are usually available only in ideal form: well-defined property rights and a well-functioning market, agencies selflessly pursuing the public interest, and so on.

Political science discussions are different. In political science the most important question isn’t, “What should we do about X?” It’s “Who gets to decide what we’re going to do about X, and how?” That leads us into the world of governance and decision making, with its messiness of competing interests, conflicting incentives, rhetorical framing of issues, ideological predispositions, and seemingly endless blocks, countermoves, and end-runs.

To some extent this is a distinction between thinking about institutions as ideal types versus thinking about institutions as problematic human creations. The latter approach involves lifting the hood and applying some diagnostics. That means knowing what to look for and what questions to ask once the hood is up.

Institutional diagnostics—questions to consider if you’re trying to make the management sustainable

To implement the Sustainable Groundwater Management Act (SGMA), people in 127 groundwater basins across California are developing groundwater sustainability agencies (GSAs) that will be required to develop, adopt, and implement groundwater sustainability plans (GSPs). That’s a governance challenge of the first order, and it involves creating new institutions or adapting existing ones for new purposes.

I strongly recommend the recently published report by Kiparsky et al (2016) on criteria for evaluating GSAs: scale, human capacity, funding, authority, independence, participation, representation, accountability, and transparency. Because those are good criteria for evaluating GSAs, they are also good criteria to take into account when designing them.

The authors of that report have done an excellent job of defining and explaining their criteria and their significance. I will add here a few thoughts about one of the criteria they cover—representation—and then add another criterion that is especially important for the notion of “management sustainability.”

Representation is critically important to governance and decision-making. If a GSA will be a new entity, for instance, what will its governance structure look like? Will the members of its governing board represent districts, represent specific constituencies, or serve at large? And if an existing entity is going to assume the responsibilities and gain the authority of a GSA, are there any changes to its internal representation and decision-making structures and processes that should be made?

Either way, will communities or stakeholders within the basin be represented equally or proportionally? If proportionally, relative to what?   Are all stakeholders equal—or, rather, should they all count equally when it comes to making groundwater management decisions? Do some have more weight because of a judgment about their stake in groundwater management? Pumpers, for example, could reasonably be said to have site-specific investments and dependence on the resource to a greater extent than others. On the other hand, if pumpers have primary control over decision-making about an overdrafted groundwater basin, will it always be a situation of “the diet starts tomorrow?” Last but not least, how can the composition of the governing body be adjusted if and when the constellation of interests and uses change?

That brings me to the criterion I’d like to add in designing GSAs and GSPs: adaptability.

An observed fact from the messy world of governance and decision-making is this: no matter how carefully and well we design institutions, we won’t get everything right the first time. Also, conditions will change in ways that alter the fit between what we put in place at one time and what comes along to confront us later.

That will surely be true for the GSAs being designed in the basins starting SGMA implementation now. Despite everyone’s best efforts in constructing these governance structures, there will be errors and surprises. It will be essential to build in processes for modification. People engaged in the hard work of groundwater management in overdrafted basins (Porse 2015) will need to make rules not only for changing groundwater use and managing the basin; they’ll need to make rules for how and when the rules themselves can be changed.

Creating a decision-making body for groundwater management isn’t just solving a problem; it’s writing a constitution. Writing a constitution is an intricate task, where decisions about one element are often linked to and affect other elements. Long-standing and relatively successful constitutions—the sustainable ones, we might say—are the ones that can be adjusted when needed.

SGMA implementation will be hard, in ways that have already been predicted and discussed (Moran and Cravens 2015, Moran and Wendell 2015). By equating it to constitution making, I don’t mean to make it sound even harder. But I think it helps to conceive of it that way. It helps us think beyond the immediate circumstances of the moment and consider the ways in which we are designing a decision making process that will have to address circumstances well beyond this moment. And that, in turn, is likely to make us think now about how we want to be able to adjust then.

As Californians design GSAs and GSPs, they are designing institutions for governance and decision-making. That’s a somewhat different, and I hope useful, way of thinking about the task that lies ahead. Thinking about it that way may help encourage everyone to think about the sustainability of the management as well as of the groundwater.

Bill Blomquist is a Professor of Political Science at Indiana University-Purdue University Indianapolis (IUPUI) in Indianapolis, Indiana.  His areas of research are water resource management, institutions, and the policy making process.

Further Reading

Kiparsky, Michael, Dave Owen, Nell Green Nylen, Juliet Christian-Smith, Barbara Cosens, Holly Doremus, Andrew Fisher, and Anita Milman (2016) Designing Effective Groundwater Sustainability Agencies: Criteria for Evaluation of Local Governance Options. Berkeley, CA: Wheeler Water Institute, UC Berkeley School of Law

Moran, Tara and Amanda Cravens (2015) California’s Sustainable Groundwater Management Act of 2014: Recommendations for Preventing and Resolving Groundwater Conflicts. Stanford, CA: Water in the West Program, Stanford University Woods Institute for the Environment

Moran, Tara and Dan Wendell (2015) The Sustainable Groundwater Management Act of 2014: Challenges and Opportunities for Implementation. Stanford, CA: Water in the West Program, Stanford University Woods Institute for the Environment

Porse, Erik (2015) “The Hard Work of Sustainable Groundwater Management.” California WaterBlog. Posted August 13, 2015.

Posted in Groundwater, Planning and Management | Tagged | 3 Comments