Electricity industry urged to save California’s salmon

The combination of hydropower and warmer water are likely to empty California’s rivers of Chinook salmon by the end of the century, a study has suggested.

Computer models taking into account climate change forecasts and the impact of dams and hydropower infrastructure showed that water temperatures are likely to be too much for the salmon to bear.

Only by changing the management of river systems are the fish, which are already suffering stress from problems like pollution, likely to cope with the river conditions during the summers, scientists warned.

Changes that might protect the salmon, without halting or severely reducing electricity generation, could include generating more power further upstream to reduce the diversion of waters lower down the rivers for hydro-power generation.

The key problem is keeping the water cool enough during the summer for the salmon that have taken part in the spring run to survive long enough to spawn in the autumn.

“There are things that we can do so that we have the water we need and also have something left for the fish,” said Dr Lisa Thomson, one of the research team and director of the Center for Aquatic Biology and Aquaculture at UC Davis.

“If we leave the water in the stream at key times of the year, the stream stays cooler and fish can make it through to the fall. I swim with these fish, they’re magnificent. We don’t want to give up on them"

Researchers from UC Davis, the Stockholm Environment Institute (SEI) and the National Center for Atmospheric Research reached their conclusions after a series of computer modelling exercises were carried out, using data from the Butte Creek watershed. The results were published in the Journal of Water Resources Planning and Management.

Dr David Purkey, of the SEI, added: “The goal should be to identify regulatory regimes which meet ecosystem objectives with minimal impact on hydropower production. The kind of work we did in Butte Creek is essential to seeking these outcomes.”