Silver Creek, June 2021

High temperatures and low levels of dissolved oxygen in Silver Creek will stress its trout population in the days ahead, The Nature Conservancy said. 

Faced with low water levels and extreme heat, The Nature Conservancy is completely closing access to fishing at the Silver Creek Preserve = ahead of the holiday weekend.

Citing low levels of dissolved oxygen, fishing access will stop at 9 p.m. on Friday, July 2, to reduce stress on the fish, the stewards of the preserve announced Thursday evening.

The unprecedented move shuts access to arguably the valley’s most popular and productive trout streams ahead of one of the busiest weekends of the year—and, according to Nature Conservancy spokeswoman Claire Cornell, underscores the “perfect storm” of conditions facing the valley right now.

“This is a significant step for us,” she told the Express on Friday. “We’ve never had to fully close access before.”

The decision comes as the valley faces the possibility of record-breaking heat in the days ahead. That's significant for the watershed, since warm water can hold less dissolved oxygen than cold water. Recent readings in the creek hit 73 degrees, The Nature Conservancy said, working to drive dissolved oxygen levels well below its threshold for “precautionary actions” to protect fish.

“These precautions are necessary for the health of the fishery to reduce stress on fish at a time when they are experiencing prolonged periods of stressful conditions,” The Nature Conservancy said in its announcement.

Those conditions are unlikely to improve in the near future as an extraordinary heat wave continues to grip the West. Temperatures in the south county are forecast to top out in the mid-90s for at least the next 10 days.

While The Nature Conservancy can block access to the waterway through the preserve and strongly deter fisherman, it can’t bar fishing in the creek itself. Only the Idaho Fish and Game Commission can do that, department spokesman Terry Thompson told the Express on Friday. As of Tuesday, the creek remained open, Thompson said.

"As long as anyone accessing Silver Creek does so by public access and stays within high water they can legally be in the water," he said. 

The Nature Conservancy will monitor conditions twice a week during that time, and plans to adjust restrictions if and when they improve. So far, though, Cornell had no estimate on reopening.

“I wish I had one,” she said. “It’s unfortunate, but it’s a perfect storm of conditions.”

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