Madison River flows drop

The Upper Madison River sees a sudden drop in streamflows below Hebgen Dam in the early morning hours on Tuesday.

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NorthWestern Energy engineers are working to repair Hebgen Dam on Wednesday after a gate component failed and drastically reduced the amount of water flowing from the reservoir into the Madison River. 

Part of a gate on the outlet structure of the dam failed early Tuesday, shrinking the opening at the bottom of the gate for the outtake of water, utility company officials said in a Wednesday morning news release. 

The malfunction led to a dramatic drop in streamflow on the upper Madison, leaving some areas dry and prompting state officials to order a full fishing closure between Hebgen Dam and Ennis Lake late Tuesday.

NorthWestern's release said its staff is working to develop a repair plan and restore flows to the Madison "as quickly as possible." The company did not say how long the repairs might take. It is also urging people to avoid the Hebgen Dam area. 

Before the malfunction, the river was running at about 650 cubic feet per second, according to data from a U.S. Geological Survey stream gauge near Hebgen Dam. After the malfunction, flow dropped to below 200 CFS. 

The drastic drop in flows left some fish stranded in riffles or trapped in side channels or pools. It also exposed spawning redds, where fish lay eggs.

The stretch between Hebgen Dam and Earthquake Lake saw the most significant impacts, but people on the river Tuesday saw low flows as far downstream as Three Dollar Bridge

Volunteers and staff from Montana Fish, Wildlife and Parks are on the river today to work to save whatever fish they can. 

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