By Jay Lund, Andrew L. Rypel, and Josue Medellin-Azuara As March begins to drag on with little precipitation in the forecast and few weeks left in California’s traditional wet season, we are in another dry year. This is California’s second dry year in a row since the 2012-2016 drought.  Statistically, California has the most drought…

by Yiqing “Gracie” Yao and Jay Lund Salinity is an eventual threat to agriculture and groundwater sustainability in parts of California, and other irrigated parts of the world. Irrigation, lower groundwater levels, and natural conditions have dramatically increased groundwater salinity in parts of California over the last 150 years (Hansen et al. 2018). Nearly two…

By Rich Pauloo and Graham Fogg Lower groundwater levels can prevent drainage of water and salts from a basin and increase aquifer salinity that eventually renders the groundwater unsuitable for use as drinking water or irrigation without expensive desalination. Pauloo et al. (2021)  demonstrate this process for the Tulare Lake Basin (TLB) of California’s Central…

by Peter Moyle A question I get asked on occasion is: Why all this fuss about endangered delta smelt when there is another smelt that looks just the same that can takes its place? The smelt being referenced is the wakasagi (Hypomesus nipponensis), which is indeed similar to the delta smelt (Hypomesus transpacificus). In fact, both…

by Jay Lund, Peter Moyle, and Andrew Rypel This updates a post from December on the likelihood of California entering a second dry year. Normally, a second dry year brings drought operations for California’s overall water system operations. Today, it is even likelier that California is entering a multi-year drought. Precipitation conditions have improved somewhat…

by Yiqing “Gracie” Yao and Jay Lund California’s Central Valley produces much of the nation’s food, including about 40% of the country’s fruits and nuts and has the nation’s second most pumped aquifer system. Its drier southern portion, the San Joaquin Valley, has decreasing surface water supply reliability due to frequent and prolonged droughts, stricter…

by Peter Moyle, Karrigan Börk, John Durand, T-C Hung, and Andrew L. Rypel 2020 was a bad year for delta smelt. No smelt were found in the standard fish sampling programs (fall midwater trawl, summer townet survey). Surveys designed specifically to catch smelt (Spring Kodiak Trawl, Enhanced Delta Smelt Monitoring Program) caught just two of…

by Jay Lund Deltas globally adjust with changes and fluctuations in external conditions, internal dynamics, and human management.  This is a short history of big changes to California’s Sacramento-San Joaquin Delta (Delta) in the past and present, and its anticipated future.  This history is important for understanding how many of the Delta’s problems have developed,…

by Jay Lund Yes, California will have another multi-year drought.  California has immense hydrologic variability, with more droughts and floods per average year than any other part of the country.  California’s water users, managers, and regulators should always be prepared for droughts (and floods).  Eventually, California will have a multi-year drought worse than any we…

By Ted Grantham, Jeanette Howard, Belize Lane, Rob Lusardi, Sam Sandoval-Solis, Eric Stein, Sarah Yarnell and Julie Zimmerman Over the past three years, a team of scientists from universities, NGOs, and state agencies across California have been working to provide guidance on how to better manage river flows for freshwater ecosystems throughout the state. A…

By: Nick Framsted Clear Lake is one of California’s oldest and most unique natural features. Nestled in Northern California’s coastal mountains, Clear Lake is the largest lake completely within California and is the oldest lake in North America with sediments dating back 480,000 years (Sims et al. 1988). Rich mineral deposits around the lake were…

By Claire Kouba and J. Pablo Ortiz Partida California’s hydrologic future is muddled by a fundamental uncertainty: will the state get wetter or drier? Climate models disagree on this question, but provide insights on other important water management questions. The wetter or drier question has been studied often in government reports (DWR CCTAG, 2015; U.S.…

By: Amber Manfree, Peter Moyle, Ted Grantham The recent removal of the sediment-filled York Dam in Napa County has reconnected two miles of steelhead trout habitat that has been blocked for over a century. While the dam itself was small and non-functional, it took nearly 30 years to accomplish removal. Thousands of barriers to stream…

by Miranda Bell-Tilcock, Jamie Sweeney, and Malte Willmes Down the dark corridors of the Watershed Sciences building are freezers of dead fish. Frozen Chinook Salmon carcasses and their dissected eyes and muscles in neat vials are stacked next to White Sturgeon fin clips, Striped Bass scales, and tubes of stomach contents. This might sound like…