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Clearwater Could Top Emergency Spillway

Officials distributed this letter to property owners below Clearwater Dam Sunday afternoon. Corps officials believe the lake level will top the emergency spillway.


Heavy overnight rains fell over the Clearwater Lake drainage basin requiring discharges through the conduit to increase this morning to 4,000 cubic feet per seCome.

The largest release ever made from Clearwater was 4,000 c.f.s. in 2011. Today, releases were at this level and we’re expected to be increased this evening.

This morning the lake was at elevation 550, with 56% of its flood storage capacity being used.

Based on the 5 inches of rain that fell during the past 24 hours, the lake is expected to crest at about 571 on Tuesday, May 4, if there is no additional rain.

The dam is reported to be operating as it should and continues to hold the flood waters that have been captured behind the dam over the past week, significantly reducing flooding downstream.

Engineers said this is what Clearwater was designed and constructed to do.

Engineers are keeping a watchful eye on weather forecasts. More rain is in the forecast for the next few days.

Once the flood storage capacity is filled, the dam will continue to hold the water currently stored in the lake, however, water still entering the lake could flow across the overflow spillway.

At this point the dam is passing inflow and can no longer regulate the river stage downstream. River flows would be as they were in their natural state before the dam was built until the lake level returns below the rim of the overflow spillway.

As Clearwater nears its water storage capacity, people should decide beforehand whether to move livestock, equipment and belongings to higher ground.

The closer to the dam you are, the faster river stages can rise. Large releases can occur during heavy rain with no more than an hour or two notice, and rapidly changing conditions could create even shorter notice.

People in at-risk areas should stay in contact with local emergency officials. If larger than normal releases are required from the dam, warnings will go out through local emergency channels.

Local officials may not know you require notification unless you have told them so.

Army Corps of Engineers personnel are monitoring lake levels and maintaining 24-hour surveillance, and the dam is sound. Personnel from the Corps’ Clearwater Lake Project Office are staying in contact with state and local officials to coordinate public safety information.



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