The lower American River is going to get a gush of cold, swift water over the holiday weekend.
Starting Friday, the U.S. Bureau of Reclamation will increase flows below Folsom and Nimbus dams from 4,000 cubic feet per second to 4,500. The flows will increase to 5,000 cfs on Tuesday.
Officials urge those boating, fishing and swimming to be mindful of safety as the flows will be swifter and colder.
The bureau says increased river flows are necessary to ensure water quality in the Sacramento-San Joaquin Delta, to maintain adequate flows to the Pacific Ocean and to help satisfy obligations to farm contractors who irrigate with Central Valley Project water.
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As the outflows increase, Folsom Lake levels will fall, as they do each summer. The reservoir is filled to 74 percent of capacity, which is just below average for this time of year.