By Andrew L. Rypel

California’s water problems are intense; so much so they are often referred to as ‘wicked’ for their extraordinary depth of complexity and general unsolvability. Yet it recently occurred to me that some of the better and more creative solutions often derive from one particular source – nature itself. Indeed, studies of nature-based solutions or ‘NBS’ are rising rapidly (Davies and Lafortezza 2019; Nelson et al. 2020; Acreman et al. 2021), and are especially popular within the NGO and environmental communities. This blog is a brief exploration of the concept, examples of nature-based solutions, both for California water and also generally, and why they might matter to us. As a fish ecologist, most of my thoughts are, as usual, focused on the status and conservation of our native fishes. I would love to hear your favorite examples of NBS or general thoughts on this topic in any area of water management or otherwise in the comments sections below.

Methods of blending Indigenous knowledge systems and Western approaches are important and also increasing (Reid et al. 2020), but have distinct connections with nature-based solutions. For example, Western science-based approaches are perhaps sometimes less effective because of an overemphasis on certainty and extent to which nature is “controllable” (Charles 2001). Indeed, Townsend et al. 2020 specifically suggests Indigenous knowledge and engagement are vital to success of nature-based solutions, especially with regards to climate change. Indigneous frameworks have the potential to help us all learn, to build back trust, and to move towards peaceful plural existence (Reed et al. 2022).

Beavers are one important nature-based solution that just aren’t discussed enough! During the early 1800s, fashion trends played an unusual role in the decline of Pacific salmon populations. Though perhaps odd to us now, at that time, the classic beaver hat was considered high fashion. Further, the main source of beaver pelts was California, Oregon, Washington, Idaho and British Columbia. Because of territorialism (e.g., between various fur-trapping regions), beavers were purposefully and quickly deleted from many salmon-producing streams to discourage nearby trapper encroachment. The net effect was something referred to as the “fur desert” (Ott 2003). Yet as beaver populations dwindled, so too did occurrence of beaver dams along the West Coast. This was a problem for fishes because native salmon and trout populations are known to exploit beaver ponds as productive rearing habitats for their young (Talabere 2002; Pollock et al. 2004; Herbold et al. 2018). For those of us interested in improving native trout and salmonid habitats, beaver conservation and reintroduction must be part of the larger fix (Wathen et al. 2019; Pollock et al. 2019). Mountain meadow restoration in particular has been floated as an important element to climate resilience in California, and is part of the California Water Resilience Portfolio. The meadow collaborative is currently working to support restoration of these systems. But scaling any substantial increase in mountain meadow acreage will need more beavers.

There are other nature-based solutions we talk about frequently on this blog. I am personally deeply engaged with the salmon-rice project. Sacramento Valley Chinook salmon evolved within a landscape full of floodplains and wetlands (see artistic recreation by Laura Cunningham, above). Juvenile Chinook salmon, born to clear snowmelt streams of the Sierras out-migrated onto the valley floor where they reared, fed on the luxurious carbon and floodplain foods, and gained energy for the final leg of their arduous journey to the Pacific Ocean. Fast forward to present day, and 95% of the floodplain in the Central Valley is gone. However, there are roughly 500,000 acres of rice fields that might be used more smartly to assist struggling salmon populations (Katz et al. 2017; Holmes et al. 2020). Mimicking historical floodplains using rice fields is already a widely known and effective conservation practice for migratory birds of the Sacramento Valley (Bird et al. 2000, Eadie et. al. 2008). Thus, it follows that these same practices might work for native fishes. We just need to figure it out! Here is a recent podcast on the topic. There is also an indication that having fish on rice fields might help mitigate flux of methane (a greenhouse gas), a concept that connects with the regenerative agriculture movement described below. 

Environmental flows are a nature-based solution that receives much attention from CWS and California scientists (e.g., Yarnell et al. 2020; Grantham et al. 2022; Yarnell et al. 2022). Perhaps “flows” are about more than just a minimum value of water needed in a river. The magnitude and frequency, timing, duration, and rate of change in flows all matter (Poff et al. 1997). Further, the quality of the water may also matter. There is rightfully much interest in this science, mainly because it aims to make the most of the water we do have, and it has also been shown to actually work (Kendy et al. 2017; Chen and Wu 2019; Tickner et al. 2020). There are interesting parallel frameworks afoot for describing natural thermal regimes of streams – see Willis et al. 2021. However, there is still much science needed to figure this all out in California, and because it involves water users and endangered species, it is bound to be controversial. Nonetheless, long-term hydrographs of natural rivers combined with ecological data on these same systems provide windows into the natural mechanics of river ecosystem function. Scientists unlocking these nature-based secrets should be in high demand by water professionals in California in the future.

‘Regenerative agriculture’ is a larger movement also worth examining within the context of NBS (Schulte et al. 2021). Agriculture is a modern miracle – we can feed many more people now on the same amount of arable land as in 1960. Nonetheless, such high productivity and land efficiency also comes at an environmental price. Effects of conventional row crop agriculture on soils (Arnhold et al. 2014; Fageria et al. 2004), insects (critical to soil health) (Wagner et al. 2021), water quality (Baker 1985), and wildlife (Brinkman et al. 2005) are well-documented (Rhodes et al. 2017). Although no legal or regulatory definition of ‘regenerative agriculture’ exists, a surge in academic research indicates the topic is gaining traction with scholars (Newton et al. 2020). Examples of regenerative agriculture include reductions in tillage, use of cover crops and crop rotations, increasing crop plant diversity, restoration of native plants and habitats, integration of free-range livestock, use of ecological or natural principals, organic methods, focus on smaller scale systems, holistic grazing, incorporation of local knowledge, and others (Newton et al. 2020). In Iowa corn and soybean fields, replacing just 10% of land with strips of restored prairie increased overall biodiversity and ecosystem services with almost no impacts to crop production (Schulte et al. 2017). In Indiana, winter cover crops decreased soil nitrate by >50% while soil N mineralization and nitrification rates increased (Christopher et al. 2021). The regenerative agriculture movement is clearly quite real and is generating innovation within the agricultural sector.

Elements of nature-based solutions are beginning to trickle into popular culture. For example, the “paleo diet” or “primal blueprint” are nouveau approaches to eating that emphasize consumption of unprocessed natural foods, similar to the way pre-industrial ancestors might have eaten. Many of the foods recommended in these diets connect back to sustainable and regenerative agricultural methods to promote consumption of nutrient-dense foods. 

Ultimately, nature-based solutions are a linked aspect to management of reconciled, working landscapes. Yet while both concepts are closely related, they are also decidedly distinct. Reconciliation ecology emphasizes balance between human and environmental needs. It also emphasizes that humans are in charge, and must assume responsibility for decision making. In contrast, nature-based solutions are often viable solutions to human problems, but are likely especially desirable inside human-dominated environments such as working lands. Indeed, one of California’s major environmental policy initiatives currently touts nature-based solutions as a method for accelerating our region’s climate change goals. These innovations will likely underpin the emerging climate solutions sector of California’s economy.

There are problems with the NBS movement too. The topic has been criticized for “green-washing” – that is, conflating and confusing public debate, wasting resources, and drawing attention away from more pressing needs (Giller et al. 2021). There are also critical questions. Where should the line be drawn as to what counts as a NBS? How should such practices be rewarded through payment programs and the like? As one example, I drove past an almond orchard the other day brightly advertising how they were ‘fighting climate change’ and ‘going to net zero’. Is this a NBS? Furthermore, there are probably cases when an engineered solution might be better. If I were living below sea level on a hurricane-prone coastline, I might prefer a really strong, well-engineered levee than a patch of mangroves. In the long-run, people and ecosystems need both nature and engineering, and there should be room for a portfolio of solutions. Further, a healthy dose of skepticism is required to properly vet any potential NBS. Fortunately, science is one of the most powerful tools ever developed to explore the efficacy of solutions – whether engineered, nature-based, or a combination.

California water has major problems, especially as we enter into another year of intense drought. We need solutions that will truly work over the long haul. Sometimes extensively engineered solutions are touted as “silver bullets” for what are actually highly complicated and long-running challenges exacerbated by hard-to-control factors like human population growth, climate change, and macroeconomics. In the case of our declining native fish fauna, it is clear that it took many years to get into this mess, and any real solution requires time to correct. Furthermore, I have the sense that we are just scratching the surface with the vast possibilities of nature-based solutions. Indigenous partnerships will be key to finding new solutions with the potential to heal both nature and our peoples. Sadly, in many cases, we don’t even know what the potential solutions might be because of shifting baselines and constant modification of the landscape. As we move forward, let’s collectively keep our eyes glued for creative nature-based solutions, listen to one another, maintain a critical eye, and collectively engage to make our landscape and water practices more sustainable for future generations.

Andrew Rypel is a Professor and the Peter B. Moyle and California Trout Chair of coldwater fish ecology at the University of California, Davis. He is a faculty member in the Department of Wildlife, Fish & Conservation Biology and Co-Director of the Center for Watershed Sciences.

Further Reading

Grantham, T., J. Howard, B. Lane, R. Lusardi, S. Sandoval-Solis, E. Stein, S. Yarnell, and J. Zimmerman. 2020. Functional Flows Can Improve Environmental Water Management in California https://californiawaterblog.com/2020/11/29/functional-flows-can-improve-environmental-water-management-in-california/

Rypel, A.L., P.B. Moyle, and J. Lund. 2021. A swiss cheese model for fish conservation in California. https://californiawaterblog.com/2021/01/24/a-swiss-cheese-model-for-fish-conservation-in-california/

Rypel, A.L., D.J. Alcott, P. Buttner, A. Wampler, J. Colby, P. Saffarinia. N. Fangue, and C.A. Jeffres. 2022. Rice and salmon, what a match! https://californiawaterblog.com/2022/02/13/rice-salmon-what-a-match/

Literature Cited

Acreman, M., A. Smith, L. Charters, D. Tickner, J. Opperman, S. Acreman, F. Edwards, P. Sayers, and F. Chivava. 2021. Evidence for the effectiveness of nature-based solutions to water issues in Africa. Environmental Research Letters 16(6):063007.

Arnhold, S., S. Lindner, B. Lee, E. Martin, J. Kettering, T. T. Nguyen, T. Koellner, Y. S. Ok, and B. Huwe. 2014. Conventional and organic farming: soil erosion and conservation potential for row crop cultivation. Geoderma 219:89-105.

Baker, D. B. 1985. Regional water quality impacts of intensive row-crop agriculture: a Lake Erie Basin case study. Journal of Soil and Water Conservation 40(1):125-132.

Bird, J. A., G. S. Pettygrove, and J. M. Eadie. 2000. The impact of waterfowl foraging on the decomposition of rice straw: mutual benefits for rice growers and waterfowl. Journal of Applied Ecology 37(5):728-741.

Brinkman, T. J., C. S. Deperno, J. A. Jenks, B. S. Haroldson, and R. G. Osborn. 2005. Movement of female white‐tailed deer: effects of climate and intensive row‐crop agriculture. The Journal of Wildlife Management 69(3):1099-1111.

Charles, A.T. 2001. Sustainable Fishery Systems. Wiley-Blackwell.

Chen, A., and M. Wu. 2019. Managing for sustainability: The development of environmental flows implementation in China. Water 11(3):433.

Christopher, S. F., J. L. Tank, U. H. Mahl, B. R. Hanrahan, and T. V. Royer. 2021. Effect of winter cover crops on soil nutrients in two row-cropped watersheds in Indiana. Journal of Environmental Quality 50(3):667-679.

Davies, C., and R. Lafortezza. 2019. Transitional path to the adoption of nature-based solutions. Land Use Policy 80:406-409.

Eadie, J. M., C. S. Elphick, K. J. Reinecke, and M. R. Miller. 2008. Wildlife values of North American ricelands. USGS Report.

Fageria, N. K., V. C. Baligar, and B. A. Bailey. 2005. Role of cover crops in improving soil and row crop productivity. Communications in soil science and plant analysis 36(19-20):2733-2757.

Giller, K. E., R. Hijbeek, J. A. Andersson, and J. Sumberg. 2021. Regenerative agriculture: an agronomic perspective. Outlook on Agriculture 50(1):13-25.

Grantham, T. E., D. M. Carlisle, J. Howard, B. Lane, R. Lusardi, A. Obester, S. Sandoval-Solis, B. Stanford, E. D. Stein, and K. T. Taniguchi-Quan. 2022. Modeling functional flows in California’s rivers. Frontiers in Environmental Science 10:787473.

Herbold, B., S. M. Carlson, R. Henery, R. C. Johnson, N. Mantua, M. McClure, P. B. Moyle, and T. Sommer. 2018. Managing for salmon resilience in California’s variable and changing climate. San Francisco Estuary and Watershed Science 16(2).

Holmes, E. J., P. Saffarinia, A. L. Rypel, M. N. Bell-Tilcock, J. V. Katz, and C. A. Jeffres. 2021. Reconciling fish and farms: Methods for managing California rice fields as salmon habitat. PLoS ONE 16(2):e0237686.

Katz, J. V. E., C. Jeffres, J. L. Conrad, T. R. Sommer, J. Martinez, S. Brumbaugh, N. Corline, and P. B. Moyle. 2017. Floodplain farm fields provide novel rearing habitat for Chinook salmon. PloS ONE 12(6):e0177409.

Kendy, E., K. W. Flessa, K. J. Schlatter, A. Carlos, O. M. H. Huerta, Y. K. Carrillo-Guerrero, and E. Guillen. 2017. Leveraging environmental flows to reform water management policy: lessons learned from the 2014 Colorado River Delta pulse flow. Ecological Engineering 106:683-694.

Nelson, D. R., B. P. Bledsoe, S. Ferreira, and N. P. Nibbelink. 2020. Challenges to realizing the potential of nature-based solutions. Current Opinion in Environmental Sustainability 45:49-55.

Newton, P., N. Civita, L. Frankel-Goldwater, K. Bartel, and C. Johns. 2020. What is regenerative agriculture? A review of scholar and practitioner definitions based on processes and outcomes. Frontiers in Sustainable Food Systems 4:194.

Ott, J. 2003. “Ruining” the rivers in the Snake Country: The Hudson’s Bay Company’s fur desert policy. Oregon Historical Quarterly 104:166-195.

Poff, N. L., J. D. Allan, M. B. Bain, J. R. Karr, K. L. Prestegaard, B. D. Richter, R. E. Sparks, and J. C. Stromberg. 1997. The natural flow regime. BioScience 47(11):769-784.

Pollock, M. M., G. R. Pess, T. J. Beechie, and D. R. Montgomery. 2004. The importance of beaver ponds to coho salmon production in the Stillaguamish River basin, Washington, USA. North American Journal of Fisheries Management 24(3):749-760.

Pollock, M. M., S. Witmore, and E. Yokel. 2019. A field experiment to assess passage of juvenile salmonids across beaver dams during low flow conditions in a tributary to the Klamath River, California, USA. bioRxiv:856252.

Reed, G., N. D. Brunet, D. McGregor, C. Scurr, T. Sadik, J. Lavigne, and S. Longboat. 2022. Toward Indigenous visions of nature-based solutions: an exploration into Canadian federal climate policy. Climate Policy:1-20.

Reid, A. J., L. E. Eckert, J. F. Lane, N. Young, S. G. Hinch, C. T. Darimont, S. J. Cooke, N. C. Ban, and A. Marshall. 2021. “Two‐Eyed Seeing”: an Indigenous framework to transform fisheries research and management. Fish and Fisheries 22(2):243-261.

Rhodes, C. J. 2017. The imperative for regenerative agriculture. Science Progress 100(1):80-129.

Schulte, L. A., B. E. Dale, S. Bozzetto, M. Liebman, G. M. Souza, N. Haddad, T. L. Richard, B. Basso, R. C. Brown, and J. A. Hilbert. 2021. Meeting global challenges with regenerative agriculture producing food and energy. Nature Sustainability:1-5.

Schulte, L. A., J. Niemi, M. J. Helmers, M. Liebman, J. G. Arbuckle, D. E. James, R. K. Kolka, M. E. O’Neal, M. D. Tomer, and J. C. Tyndall. 2017. Prairie strips improve biodiversity and the delivery of multiple ecosystem services from corn–soybean croplands. Proceedings of the National Academy of Sciences 114(42):11247-11252.

Talabere, A. G. 2002. Influence of water temperature and beaver ponds on Lahontan cutthroat trout in a high-desert stream, southeastern Oregon. MS Thesis Oregon State University.

Tickner, D., N. Kaushal, R. Speed, and R. Tharme. 2020. Implementing environmental flows: Lessons for policy and practice. Frontiers in Environmental Science 8:106.

Townsend, J., F. Moola, and M.-K. Craig. 2020. Indigenous Peoples are critical to the success of nature-based solutions to climate change. FACETS 5(1):551-556.

Wagner, D. L., E. M. Grames, M. L. Forister, M. R. Berenbaum, and D. Stopak. 2021. Insect decline in the Anthropocene: death by a thousand cuts. Proceedings of the National Academy of Sciences 118(2).

Wathen, G., J. E. Allgeier, N. Bouwes, M. M. Pollock, D. E. Schindler, and C. E. Jordan. 2019. Beaver activity increases habitat complexity and spatial partitioning by steelhead trout. Canadian Journal of Fisheries and Aquatic Sciences 76(7):1086-1095.

Willis, A. D., R. A. Peek, and A. L. Rypel. 2021. Classifying California’s stream thermal regimes for cold-water conservation. PloS ONE 16(8):e0256286.

Yarnell, S. M., E. D. Stein, J. A. Webb, T. Grantham, R. A. Lusardi, J. Zimmerman, R. A. Peek, B. A. Lane, J. Howard, and S. Sandoval‐Solis. 2020. A functional flows approach to selecting ecologically relevant flow metrics for environmental flow applications. River Research and Applications 36(2):318-324.

Yarnell, S. M., A. Willis, A. Obester, R. A. Peek, R. A. Lusardi, J. Zimmerman, T. E. Grantham, and E. D. Stein. 2022. Functional flows in groundwater-influenced streams: application of the California environmental flows framework to determine ecological flow needs. Frontiers in Environmental Science:752.