Eline Anvik
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California is the most populous state in the United States. The sunshine state also contains large fertile lands, placing California in the position to handle a great percentage of the countries agricultural demands. Because of these characteristics there is a high water demand that often prioritizes urban and agricultural demands, leaving ecosystems underrepresented in the water balance. This can be particularly harmful to species whose habitat lies in sensitive streams, who have adapted to historically unimpeded flows.
Two sensitive species include the endangered anadromous Chinook salmon and Steelhead trout. In order to assist a local Californian water utility with protecting these species and implementing environmental flows, a Water Evaluation and Planning (WEAP) model was developed, including an integrated novel biological evaluation framework (BEF). The BEF allows for habitat suitability indexes to be calculated for each endangered species during its various life stages along chosen points of the watershed streams. The combination addresses the pressing issue of integrating ecosystem considerations in water planning, by linking dynamic urban flows with ecological factors at the watershed scale. The model with BEF provides an early warning system for sensitive species, including the Chinook salmon and Steelhead trout. Model outputs predict stream temperature and flow based on predicted climate, utility operations, and imported water supplies. The modeled stream conditions are then compared to the tolerable thresholds of each individual species to predict when habitat conditions will become perilous.
Using modeled results communities can confirm that reservoir releases are providing adequate conditions for the environment, or learn that changes like increased cold water management need to be made to increase survivability of sensitive species. In California the model has been used to influence important ecological decisions. Summer 2021 model predictions estimated high temperatures in Santa Clara stream reaches equating to a low habitat suitability index, putting the endangered species in grave danger. In response to the modeled results, a fish rescue took place in June 2021, saving the endangered fish from potential extinction. In the future the methods used for the BEF could be changed to fit the habitat requirements of other species. When combined with a WEAP model, communities are able to predict and make necessary changes to ensure adequate protection of local endangered species.
Source: Calderon, C. (Stockholm Environment Institute). 2021. Model System to Protect Endangered Aquatic Species. Managing ecological and climate risk, Risk & Resilience. AIWW 2021.
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Icon image: Wikimedia Commons- water life