Icicle Creek Irrigation District Ends Emergency Declaration at Eight Mile Lake

The Icicle and Peshastin Irrigation Districts vote to end their declared emergency at Eight Mile Lake at their October 9^th board meeting.  Many people have worked hard to lower the risk posed by the Jack Creek fire.  The Districts declared a state of emergency on March 13^th, 2018 due to the threat of increased run off posed by the Jack Creek fire from the fall of 2017.  The Boards of the districts felt that the 90 year old dam was not capable of safely handling the amount of run off that could come out of the burned water shed.  The dam had sustained damage back in the 1990’s from very high run off and the outlet pipe that is used to release water out of the lake was partially plugged/collapsed and could only pass about 5 cubic feet per second (CFS) or about 2,250 gallons per minute.  It was designed to handle more than 25 CFS.  The districts flew an excavator up to the lake and removed about 50 feet of the earthen portion of the dam and hardened the area with rip-rap, increasing the spillway from about 13 feet to 63 feet wide.  They also removed a portion of one of the rock and cement walls that was no longer supported and would now have water going around it on both sides.   It was believed that debris would collect on the wall and could break it off releasing a large surge flow down the creek.  This portion of the work was done back in early May.  The districts had to wait until it could lower the lake level before it could attempt to unplug the outlet pipe.  The water level in the lake was finally lowered enough to get into the outlet pipe in early August.  It was determined that the pipe was not plugged but had collapsed.  It was a made in-place log stave pipe and a couple of sections had collapsed.  The districts were able to replace the pipe and lower the lake further.  The water in the lake as of September  26^th was 16 feet  below the new spillway.  This amounts to approximately 1,200 acre feet of flood control storage space.  With this much storage available the reservoir could likely withstand a storm that dropped 4 inches of rain in an hour.  The Department of Ecology helped out by installing monitoring equipment at and below the dam so that we can keep an eye on things and warn those that might been in the line of possible flooding that might occur do to a dam breach.  They also helped the district with an Emergency Action Plan.  The Chelan County Emergency Management Office also helped in developing the Emergency Action Plan as well as public notification of the danger posed.  It is important to note that while the dam is much safer than it was at the beginning of the year it still is not up to today’s dam safety standards.  The district is working to replace the dam with a new dam that meets today’s standards as soon as possible.