"Water releases from dams aren’t that good at mimicking natural conditions, a new study finds."
"As California’s prized salmon runs teeter toward extinction in another crushing drought, a new study highlights the need to rethink dams — a key part of the state’s water management.
For decades, water managers have released water from reservoirs in an attempt to mimic natural stream flows and temperatures, with a special eye on keeping water cold enough for salmon, which can’t tolerate temperatures above 72 degrees Fahrenheit. The belief was that California could dam most of its rivers to grow cities and food but continue to support wildlife if enough cold water was released from dams at the right time.
But the study, published in PLOS One, could call some of that management paradigm into question. Researchers from the University of California, Davis analyzed stream temperature data from 77 sites, including 27 dams. They found that only one site — Shasta Dam — created temperature patterns that resemble natural ones."