SLO County doesn’t have to release more dam water to protect trout, court says
San Luis Obispo County doesn’t have to increase the amount of water it releases from Lopez Dam, a federal court ruled this week.
Lopez Lake supplies drinking water to about 50,000 South County residents. Meanwhile, water released from the reservoir into Arroyo Grande Creek provides critical habitat to steelhead trout, which are designated as threatened under the Endangered Species Act.
After a coalition of environmental groups sued the county, a U.S. District Court judge ordered the county in 2024 to release more water from Lopez Dam to support steelhead trout migration through Arroyo Grande Creek.
The coalition included San Luis Obispo Coastkeeper, Los Padres ForestWatch, the California Coastkeeper Alliance and the Ecological Rights Foundation.
The county appealed the decision last year, saying that releasing the prescribed amount of water into the creek would wash away the eggs of two other protected species: the tidewater goby and the California red-legged frog, according to court documents.
But the environmental groups argued that while the flows could wash away a handful of goby and frog eggs when it is first implemented, increasing the amount of water in the creek will eventually improve the habitat for the tidewater goby and red-legged frog — whose populations will increase over time.
Last year, the U.S. Court of Appeals for the Ninth Circuit said the county can return to its previous, lower-volume water release schedule for Lopez Dam for the time being — due to concerns over the impact to the goby and the frogs.
The U.S. Court of Appeals agreed that the increased water release schedule would benefit steelhead trout, but it ordered the lower court to prove that it wouldn’t harm the tidewater goby and California red-legged frog before requiring the county to implement it.
The higher court sent the case back to the district court to re-evaluate the water release schedule.
On March 4, the coalition filed a new motion that addressed the court’s concerns about the tidewater goby and red-legged frog.
But still, on Monday, the U.S. District Court for the Central District of California denied the environmental groups’ motion to order the county to implement the increased water release schedule.
The court said the environmental groups did not adequately prove that the increased water flows wouldn’t harm the tidewater goby and the California red-legged frog, according to the decision.
This means the county can continue implementing its existing lower water release schedule.
Christopher Sproul, the attorney for the environmental groups, said his clients are evaluating more legal avenues to compel the county to release more water from the dam.
“We hope in the long run that the courts will be persuaded that protecting endangered steelhead is a high priority,” Sproul said.
The county, however, celebrated the decision.
“The county remains committed to protecting the diverse species that depend on the Arroyo Grande Creek watershed while maintaining reliable water service and public safety,” San Luis Obispo County Public Works Director John Diodati said. “This ruling allows us to continue operating Lopez Dam responsibly while we complete the federal review process for our Habitat Conservation Plan and continue balancing water supply reliability with habitat protection.”
San Luis Obispo County Supervisor Jimmy Paulding agreed.
“Our board has consistently supported responsible stewardship of both our water resources and our environment,” he said. “We’re pleased the court recognized that these extraordinary requests were not supported by the evidence presented.”
