Despite recent snowmelt, danger remains at Eightmile Lake

With the flooding danger still possible at Eightmile Lake, the Washington Department of Ecology is installing sensors at the dam to provide a potential warning if there were dam failure.
“The Department of Ecology is handling this stuff. We took their guy up there on April 9. He was checking for satellite reception from up there so he could send out signals. We did find a satellite we could talk to up there,” said Tony Jantzer, Icicle and Peshastin Irrigation District manager. “Right now, they are in the process of gathering up all the equipment they need. My assumption is they will have monitoring telemetry up there by about May 15. They have a video camera, rain gauge and hook into the depth.”
There is already a transducer at the lake which senses depth. Jantzer said they’ve been using it for the past couple years, but there has been no way to broadcast that information. Their only choice was to hike up there and read it.
The WSDOE will hook into that transducer, he said, and also put a flow monitor in the creek below the lake and also possibly at the trailhead. Jantzer believes the information will be available on the WSDOE website.
The mostly earthen dam was built in the 1920s to provide additional water to Icicle Creek for irrigation. The dam is managed by the Icicle Irrigation District.
The Jack Fire last fall burnt the watershed above the lake, making a rapid melt off a distinct danger. The resulting flood could rise the Icicle Creek to above historic flood levels. An emergency declaration has been made because of this.
Jantzer said he’s been going up to the lake every two weeks, but now more often due to the rapidly melting snow.
“The lake is basically full. There is about two feet of water going through the notch in the dam, which is a designed spill,” Jantzer said. “The water was just starting to go over the earthen part of the dam, where it is not supposed to go.”
The snow around the lake, which is posing the danger, has been melting, especially during the recent hot spell. “The north facing hillside is probably still covered with 80 percent snow. The south facing hillside is probably about 80 percent melted off,” Jantzer said. “We’ve lost a lot of snow. There’s probably 50 percent snow left up there. That is why the lake filled up. I would characterize the water coming into the lake is more than is going out of the lake.”
The lake will continue to rise, he said. Jantzer said he has seen water going over the earthen section of the dam before, which did not cause any problems. It has been eroding over 20 years, so it hasn’t really changed.
“If it stays down in that realm, we’ll be okay. I don’t anticipate, given our weather pattern the next couple weeks, that it will be any high risk. But if we do get a big storm to come in and the lake is already a foot or two going the earthen section, and increase that dramatically, we could have a problem,” he said.
The biggest concern right now is the increasingly hot weather, which will cause the snow to continue to melt and fill up the lake, which should be okay. Jantzer believes the dam will handle that, but if that changes to a big rain event, then the runoff could inundate the lake.
Jantzer said they are considering two possibilities for dam.
“We’re really trying to get to the point where can replace the entire dam. We really want to do that this year. We are working towards that,” he said. “If we don’t think we can get that done, we do have some plans for interim fixes to the dam, harden the dam, make a bigger spillway to get the dam to where it can come out of this emergency situation.”
The irrigation district will not be able to end the emergency declaration until they have made some physical changes to the dam. Plans are to take an excavator up there as soon as the snow allows.
Jantzer has been going up to the lake via aircraft, since hiking to the lake would be pretty arduous in the snow.
“I have a friend who lives locally and has a plane designed for doing this type of thing. He gives me rides when he’s available. Otherwise, I fly up there with a helicopter from Valley Helicopter out of Ellensburg,” Jantzer said. “Until we get the monitoring equipment up there, we’re trying to get up there as often as we feel the conditions warrant. Right now, we want to get up there once a week to look at it.”
Once the monitoring equipment is in place, he believe they won’t have to go up there much unless there is some kind of incident. The plan is to get things ready to prepare for whatever they can do.  
Ian Dunn can be reached at 548-5286 or editor@leavenworthecho.com.