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Using GoldSim to Simulate the Impact of California’s Water Management Practices on Salmon Populations

California’s salmon population has plummeted more than 88 percent since its all-time high five years ago, reaching a near-record low. Such unprecedented collapse is coupled with an increasingly arid environment and dwindling water resources, burdening the state with exceedingly complex water management issues that affect humans and wildlife alike. As in any ecosystem, critical (and sometimes unexpected) cause-and-effect relationships exist; one small fluctuation in water flow or temperature, for example, can have a profound, long-term impact on salmon. Accordingly, it was imperative that California’s water management strategies not only met state-wide water needs but also helped recover and sustain its troubled fish populations.

That was easier said than done. Storing and delivering water while minimizing disturbance to the natural environment was – and continues to be – a very delicate balance. To compound the complexity further, scientists and decision-makers needed to ensure their strategies were based on sound quantitative – not just qualitative – research. (While scientists have worked to model and quantify such cause-effect relationships in the past, the methods used were cumbersome and based on old technology. Excel spreadsheets were the tools of choice, yet had limited capacity and were difficult to explain to scientists, state officials, and the public.)

To help in this difficult task, the State of California and Cramer Fish Sciences (Cramer), a Sacramento fisheries and environmental consultancy chose to use GoldSim develop a salmon life cycle model that analyzed how each of four proposed water management strategies would impact the state’s salmon populations.

The model was a resounding success. It forecasted how small changes in various water projects would affect current and future salmon populations. Using the GoldSim model, Cramer was able to identify the most viable, environmentally-friendly water management strategy for the state.

The GoldSim model empowered Cramer with a level of scientific confidence and detailed modeling that had theretofore been unattainable. “That’s hugely important,” said Brad Cavallo, a fisheries scientist at Cramer. “Previously, our research was more about what we think the relationships are. Using GoldSim, however, we can computationally show the likely outcomes of alternative water project operations, habitat improvement actions, and fishery management strategies.”

Equally important, the modeling results were no longer limited to mathematically-inclined scientists. GoldSim’s user interface translated the complex computations into an understandable, more layman-friendly format that not only resonated with scientists across the field but also state decision-makers.