NOT THE DAM!
Priest Lake, Idaho - December 23, 2022.
IN A RECENT ARTICLE to the Spokesman Review, titled "A key element of Priest Lake Basin needs our protection", the author laid out his concerns about the health of the lower Priest River as well as his opinions on how those problems might be resolved. The thrust of his position was to remove the Outlet dam.
It is true that the Priest River is impaired from its historic existence as a cold water fishery; that is, a river that runs cold enough year-around to support native trout. However, it’s overly simplistic to blame the Priest Lake Outlet dam for the river’s woes. To the contrary, removing the dam would likely be even more detrimental to the river’s health. Let’s consider the facts and predictable effects of removing the dam:
Decreased flows: The water flows coming into the lake will remain the same, regardless of whether there is a dam or not. The dam’s purpose is two-fold. It allows the lake level to be regulated and held to a specific elevation, and it provides a means to store vast quantities of water for downstream needs.
The available outflow of Priest Lake is entirely from melting snowpack and atmospheric moisture—snow or rain. With the dam operating as intended, spring snowmelt flows basically unimpeded through the wide open dam gates. As the runoff abates, the gates are systematically closed to maintain a summer pool level about 3ft above winter level. After summer pool is stabilized, typically in mid-June, all water coming into the lake spills through the dam into the river.
So what would be different if the dam were removed? Well, winter and run-off levels would basically be the same, but as soon as the snowmelt abates, the lake level would begin lowering back to winter levels, timing dependent entirely upon atmospheric conditions. From what we know historically, before the dam placement, by early August the lake would typically be most of the way down to winter levels again. And in a drought year such as 2015 the lake would likely never even achieve normal summer level! Without a dam to regulate water levels, what comes in will go out very quickly.
An unregulated lake level would create unimaginable problems for recreational use. And when the lake reached its lowest level there wouldn’t be any more water flowing out of the lake than what goes over the dam now. It’s really very simple: Water in, water out. No management of lake level, not one bit more water for the lake to share with the river.
Temperature: The article also asserts that “location and operation” of the Outlet dam results in water pooling in the 1/2 mile long upstream channel, increasing the water temperatures going over the dam. This may be true to an extent, but consider how the temperature would be affected without the dam. There would be no limiting factor of how low the lake level would draw down. The Outlet channel would cease to exist, becoming simply part of the river channel. And the river would still be getting surface water right off the top of the lake as it spills out of the very shallow Outlet Bay.
And what would happen to the rest of the Lake? Well, any of today’s shallow areas—all of Outlet and Coolin Bay, Sherwood all the way to Steamboat, Bear Creek, Two Mouth, the Thorofare and Beaver Creek -all of those areas would be 3-4ft shallower during summer season! Imagine that! How much more shallow lakebed would be subject to increased temperatures? How many more unstratified acre/feet would be warmed to significantly higher levels than now? Wouldn’t that very logically increase the surface temperature of the whole lake, and significantly raise the discharged water temperatures going into the River?
Everyone who now enjoys the use of Priest Lake as we know it would be terribly impacted by the dam’s removal. Shorelines would change dramatically, all of the docks would have to be extended or moved further out to access mooring depths, more navigable hazards would be exposed, the Thorofare would again become closed off, harmful algae and other noxious plant life would likely spread. Our Lake would cease to be what we have today. But one thing wouldn’t change. The health of the Priest River would be unlikely to improve at all! Indeed, the river would likely be harmed even more by warmer temps and longer duration of low flows.
There is much to consider in how we might maintain, improve, and protect the whole Priest River Basin, including all of Priest Lake. Hopefully the newly formed Watershed Study Group will approach the issues with common sense and obtainable goals, not crazy off the wall notions like removing the dam or siphoning cold water from our lake!
We must demand that whatever actions are taken, THEY DO NOT HARM PRIEST LAKE.
Stop the Priest Lake Siphon Committee