Classifying California’s stream thermal regimes for cold-water conservation

by Christine A Parisek
August 30, 2021

Study of California Streams Reveals Fish Give Dams the Cold Shoulder

New research by CWS researchers Drs. Ann Willis, Ryan Peek, and Andrew Rypel, shows that dams are ineffective for cold-water conservation and California's regulated streams fail cold-water ecosystems.

The study modeled the thermal regimes of 77 California stream sites to evaluate variation nested within each stream class (stable warm, variable warm, stable cool, variable cool, and stable cold). Across California, the thermal regimes of cool- and cold-water streams varied. In addition, the study found that "contrary to what is often assumed, California reservoirs do not contain sufficient cold-water storage to replicate desirable, reach-scale thermal regimes."

In an exerpt from the press release:
"Of California’s 1,400 dams, only one very large and highly-engineered dam — Shasta — stood out in the study as replicating natural cold-water patterns. While the study does not suggest removing all dams, identifying 'deadbeat dams' that have expired or where there are critical ecosystems that support fish, people, biodiversity and clean water could restore natural processes amid climate warming and other stressors. 'We falsely equate dams with water security,' Willis said. 'More storage does not mean more water. A giant, empty refrigerator doesn’t help you if you’re starving. The same is true for water.'"

Read the paper and media coverage below to learn more about this study!