Keeping reliable water flowing through Manteca and Lathrop household taps and irrigating Ripon almond orchards could come down one day to how well rainbow trout are doing in the Stanislaus River.
It is why South San Joaquin Irrigation District and Oakdale Irrigation District have been spending $1 million on an annual basis to secure expertise of FISHIO scientists, biologists, and technicians to monitor fish and river conditions as well as to work toward creating more spawning habitats.
The goal is not only to be good stewards of the environment but to avoid any federal intervention for the fish protected under the Endangered Species Act.
The effort isn’t to counter federal and state research used to make water release decisions from New Melones Reservoir but rather to provide scientific data. No federal or state agencies have done any research on rainbow trout on the Stanislaus.
The research is not being done to take an adversarial role with the Bureau of Reclamation or State Department of Water Resources. Instead it is counter edicts by other agencies such as the biological opinion by the federal Fish and Wildfire Service. The districts have successfully used data they have collected to prevail in federal court. Decisions of judges have noted the lack of research backing up the federal stances regarding water flow and other issues.
The most recent battle earlier this year centered on the timing of releases. The federal government has been operating on the premise more water means more fish. FISHBIO data made a clear link between water temperature and survival rates. The districts used that to rally against a plan that would have released more water for the fish earlier in the season and not leave enough “cold water pool” behind New Melones for the critical summer and fall period when water temperatures rise.
Such a strategy, the districts argued, would essentially have fried the fish.
The research also seems to verify a 2014 study by the state Department of Water Resources that 95 percent of young salmon and steelhead are eaten by predators such as bass before reaching the Delta.
To that end, research points to a need to address predators that lurk in deep pools between Riverbank and the Stanislaus’ confluence with the San Joaquin River.
Habitat restoration is also key. The OID initiated a $1.1 million project at Honolulu Bar that was completed in 2012 to restore spawning habitat and create a safe haven for juvenile fish.
By adding gravel and restoring floodplain habitat as well as removing non-native vegetation, research shows fish numbers could be increased.
Rainbow trout and steelhead are the same species. Scientists are not exactly sure what environmental factors or inherited traits determine what type of fish a juvenile grows into — rainbow trout that stay in freshwater ort steelhead that migrate to the ocean.
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