A juvenile chinook salmon from the Klamath River shows signs of parasitic infection and disease. Jes Burns, OPB/EarthFix

Farmers, fish advocates, tribes and government officials are headed to federal court in California on Wednesday to argue who will get water — and when — in the Klamath Basin.

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Federal dam operators are asking to open the irrigation season next week in lieu of holding back water to benefit fish.

In recent years, salmon in the Klamath River have suffered from high rates of disease. Warm water and low flows on the dam-controlled river helped a parasite ravage juvenile fish at rates far higher than federal protections allow.

Klamath coho salmon are listed as threatened under the Endangered Species Act. The biological opinion that governs how they are managed says disease rates cannot top 50 percent. But infection rates ballooned to more than 80 percent of fish in both 2014 and 2015. Local tribes blamed the Bureau of Reclamation, which is required to manage water in a way to keep disease rates in check.

Local tribes and fish advocates sued. In 2017, a judge ordered federal dam operators to hold back a large chunk of water in Upper Klamath Lake through late spring in case the parasite concentrations once again got too high and needed to be diluted downstream.

Related: Captive-Raised Native Sucker Fish Make 1st Ever Return To Klamath Lake

But that, along with requirements to keep a certain amount of water in Upper Klamath Lake to protect endangered sucker fish, means basin farmers can’t get irrigation water until early summer.

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“It really puts our backs against the wall to where we’re not even able to start. And really, there should be water in the canals by now,” said Scott White of the Klamath Water Users Association.

Irrigator concerns are heightened this year because of the coming tight water year. Snowpack is at 45 percent of average for the Klamath Basin.

But Earthjustice attorney Patti Goldman said the same urgency needs to be applied to fish.

“The bureau has compared this year to 2015 in terms of the amount of water and the predictions for a dry year," Goldman said. "That’s the year when the infection rates of the salmon that were sampled were 91 percent."

Goldman will be representing environmental and fishing groups at the federal hearing.

Recent cool and rainy weather in the Klamath Basin has so far helped keep the parasite at bay. Federal scientists have not detected any infected fish this year, but it is very early still.

Rain this past weekend also allowed the Bureau of Reclamation to meet part of its court-ordered obligation to protect salmon. It significantly increased river flows to help flush parasites out of the system.

“It may be that Mother Nature will bail us out this year and we won’t have a fight over water,” said Craig Tucker, with the Karuk Tribe.

But he adds that if the region experiences a heatwave, much of the benefit from the late precipitation could be lost.

If the farmers and federal water managers prevail in court Wednesday, water will start flowing into irrigation canals April 19.