Three irrigation districts are blaming the federal Bureau of Reclamation for failing to adjust water releases from New Melones Reservoir to protect spawning Chinook salmon in the Stanislaus River.
The districts contend the federal agency failed to heed their repeated warnings to more aggressively reduce reservoir storage throughout the year. As a result of high flows during the fall spawning season, more than 10 percent of the salmon eggs appear to have been wiped out between the Knights Ferry and Orange Blossom (Honolulu Bar) area on the Stanislaus River based on work conducted by a team of fishery research scientists with the Oakdale-based FISHBIO firm.
Nearly continuous high water flows during October resulted in salmon spawning in side channels and other areas of high flow. The lowering of the flows led to the eggs of the “species of concern” under the federal Endangered Species Act being wiped out. The eggs were destroyed in at least 23 redds, where salmon nest and spawn, in the Knights Ferry to Orange Blossom area alone.
“We have been warning the Bureau since mid-summer,” noted Steve Knell, general manager of the Oakdale Irrigation District. “We told the (Bureau) this would happen if they didn’t manage their water releases. We didn’t want the salmon to nest in the floodplain during high flows, only to get stranded if the flows were reduced. For whatever reason, the (Bureau) ignored our concerns and the result was a significant and needless loss of salmon.”
Joining OID in criticizing the Bureau were the South San Joaquin Irrigation District and the Stockton East Water District. The OID and SSJID have spent over $1 million in the past decade working to improve fish habitat and survival on the Stanislaus River.
Fall-run Chinook salmon represent the only race of salmon that spawn in the Stanislaus River. Fall-run Chinook salmon need flow rates of approximately 300 to 500 cubic feet per second of water flow beginning in early October each year, to maximize spawning success.
“This year, the (Bureau) maintained flows in excess of 2,000 (cubic feet per second) until Nov. 2,” according to Jeff Shields, SSJID general manager.
“These salmon spawned in areas where the high flows covered the redds,” he added. “When the (Bureau) reduced the river flows, the redds became dewatered.”
Earlier this year the SSJID and OID succeeded in convincing the federal district court judge that a proposed federal operating plan to send massive amounts of water down the Stanislaus in a bid to protect salmon would ultimately be counterproductive. That’s because the pool of water behind New Melones would be so low in some years that the temperature of the “cold water storage” on the bottom of the reservoir would raise water temperatures sufficiently to kill fish.
Fish biologist Doug Demko said there had been an increase in the number of fall-run salmon returning to spawn in the Stanislaus River this year. The OID invested heavily in creating new spawning areas for the salmon as well. Demko said the Bureau’s management of New Melones releases means the number of juvenile fish heading to the Pacific Ocean this year will be reduced, which in turn will further cut the amount of adults that return in subsequent years to spawn.
Demko said the Bureau was sent a memorandum in July warning of the danger of heavy release in the spawning season but got no response.
The Bureau has not responded to requests for an explanation of why releases were allowed to jeopardize the survival of the Chinook salmon.
Manteca Bulletin Managing Editor Dennis Wyatt contributed to this report.