PRESS RELEASE: Groups and Tribe Urge Regulators to Control Toxic Pollution from Selenium

PRESS RELEASE April 3, 2024

In an April 1, 2024 letter to three water boards, fishing and conservation groups and a Tribe have urged regulators to control recently measured excess levels of selenium in Mud Slough. Mud Slough drains selenium-impaired land on the west side of the San Joaquin Valley into the San Joaquin River and ultimately San Francisco Bay. Selenium is known to cause reproductive failure, deformities, and death in fish and waterfowl.

“Our groups have spent over a decade at the water boards and in court trying to bring runoff from Mud Slough into compliance with water quality standards,” said Chris Shutes, Executive Director of the California Sportfishing Protection Alliance. “Past selenium discharges accumulated in downstream waters, impacting fish and causing deformities. The water boards need to act to protect fish and wildlife from this toxic pollutant.”

Previous action by the water boards limited discharges of water from Mud Slough to San Joaquin Valley wildlife refuges. It required the San Luis and Delta-Mendota Water Authority to instead supply the refuges with better quality groundwater. However, a new plan would resume delivery of water from Mud Slough to the refuges. Considering the history of waterfowl deformities in San Joaquin Valley refuges due to selenium contamination, the proposed change in source water is particularly alarming.

San Joaquin Valley wildlife refuges are part of the Pacific Flyway. Birds that stop in these refuges migrate as far away as Alaska.

The letter cites to a 2018 study which found that selenium deformed Sacramento splittail, a native fish, in the San Joaquin River. It calls on regulators to strengthen the standards for selenium pollution, beginning with a wet-year monitoring program of splittail funded by the Water Authority.

More broadly, the letter calls on the board to enforce existing protective standards for wetlands and to adopt more protective standards consistent with the findings of the Environmental Protection Agency of what is necessary to protect fish and wildlife.

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