As fish deaths increase at pumps, critics urge California agencies to improve protections

She said she hopes the outcry will spur discussion to protect fish populations.

“I think it’s possible. It’s just unfortunate that so many fish have to die in the process to get there,” Overhouse said.

The losses of fish coincide with other debates over how water should be managed in the delta. Regulators are considering alternatives for new standards and flow requirements that will determine how much water may be drawn from the delta.

Additionally, Gov. Gavin Newsom presented a plan last week outlining his administration’s priorities for changing how the state manages water to adapt to more extreme droughts and floods related to climate change. Newsom’s priorities include fast-tracking development of Sites Reservoir, the first new major reservoir in decades, and moving ahead with the proposed Delta Conveyance Project, a 45-mile tunnel that would transport water beneath the delta.

Nemeth said the restrictions on pumping have come at a cost to supplies. With a likely return of La Niña that could bring drier conditions, she said, “now is the time to capture and store this water while it’s available.”

“These conditions speak to the critical need to continue to advance the Delta Conveyance Project, which is an important part of how we can manage the impacts of climate change,” Nemeth said.

She said that in a wet year like this, the tunnel would allow the state to capture more water during high flows and store it for dry times, and “do so in a way that minimizes impacts to fish species.”

Rosenfield disagrees. He said state officials are wrongly assuming that tunnel fish screens would be more effective and argued that the tunnel would harm endangered fish and the delta’s ecosystem.

The rise in fish deaths is a symptom of a larger problem, Rosenfield said: California diverts too much water from the delta, to the detriment of its ecological health.

“From the fishes’ perspective, our unsustainable water diversions cause a nearly continuous, man-made drought — a drought so severe that numerous species that have thrived in the delta for eons are all declining toward extinction,” he said. “A delta tunnel will divert more water, not less.”