How to Fill a Lake
Rep. George Eskridge clarifies the process behind Lake Pend Oreille water levels
Water, all this rain and water, so why isn’t Pend Oreille Lake full? A constituent sent me an e-mail shortly before Memorial Day expressing his disappointment in the lake level, stating: “This weekend is Memorial Day weekend, which for most people marks the symbolic start of summer. Here in Bonner County we won’t be able to enjoy our lake for Memorial Day Weekend because it is projected to be more than three feet below full pool level.” He goes on to state that Lake Coeur d’Alene already has a full lake and asks, “why is Coeur d’Alene full and Lake Pend Oreille empty?”
My response to the question was in part as follows:
The level of Lake Pend Oreille is dependent in part on the operation of Albeni Falls Dam in coordination with other hydro projects on the Columbia River system, including not only dams within the Northwest U.S. border, but also in coordination with dams on the Columbia River system on the Canadian side.
The operation of Albeni Falls Dam is based on a multi-purpose use concept, with the number one priority identified as flood control, both upstream and downstream from the dam. Other uses include operations benefiting electric power generation, recreation and fish interests.
Electric power generation used to be second in priority. However, since passage of the Pacific Northwest Electric Power Planning and Conservation Act on December 5, 1980 (since renamed the Northwest Power Act), fish mitigation competes with power in terms of the second priority and recreation is on a competing basis with power generation as well.
Given this, the Army Corps of Engineers with input from a multitude of special interests, attempts to balance all of these uses as effectively as it can. As an example, the fall and winter operation of Albeni Falls has been influenced by the Idaho Department of Fish and Game to recover the Kokanee population.
Given all this however, flood control remains the major decision factor on refill of Lake Pend Oreille for the summer period. The COE is obligated to ensure that the lake level in the spring and early summer period is low enough to absorb the spring runoff of the winter snowpack and anticipated precipitation levels to avoid flooding. They also have to account for inflow into the river from tributaries such as Priest River that impact Pend Oreille Lake and River levels.
Before responding to the constituent’s question, I asked the COE for information relative to this year’s Pend Oreille refill operation. I was informed that at that time (Memorial weekend time period) that COE was “filling the lake gradually to allow for safety margins to accommodate late snowpack runoff and a high amount of rainfall over the past few days to avoid flooding.” During this time Priest Lake was also reaching full elevation, adding to the inflow to Pend Oreille River from Priest River.
In preparation for this article I obtained more information on water supply in the Panhandle and its relation to lake refill and the concern of the COE relative to flooding issues.
On June 1, the Panhandle’s snowpack was just a little more than half melted. Our rivers have seen multiple stream flow peaks as our snowmelt rates have varied up and down, and sporadic and heavier than normal June rainfall has added to the problem.
As of June 1, Lake Pend Oreille was at 77 percent of capacity, Coeur d’Alene at 87 percent capacity (not full as it may have seemed) and Priest Lake at a “little more than its normal summer capacity.” The June 1 information also stated “the June-July stream flow volume forecasts are 125-150 percent of normal for Moyie, Smith, Boundary and Priest Rivers; other streams are 107-116 percent.”
Our normal summer pool lake elevation at the Hope measuring station is 2062.5 feet; on Saturday, June 30, the lake elevation was 2062.3. At the same time the COE Public Affairs Office issued the following press release:
“Due to near record rainfall in northern Idaho and Montana, Albeni Falls Dam released water at a rate as high as 98,000 cubic feet per second, and while flows are slowing, Army Corps of Engineers park rangers urge caution at Pend Oreille beaches.”
The COE press release went on to state that “the river basin (Pend Oreille and Priest Lake, etc.) just got hit with two storm systems. Current precipitation for the month of June is 6.6 inches, more than 294 percent of the June average, which is 2.44 inches.”
During the later days of June, as a result of snowpack runoff and higher than normal rainfall, we have been informed of potential flooding downstream from Albeni Falls. Not related to this basin, but in support of the COE’s conservative operation of Albeni Falls, we are experiencing near flooding on the Kootenai River because of abnormal rainfall and various melting regimes of the snowpack.
I realize that all of us look to a full lake as early in the spring and as late in the fall as possible and would like to see a different refill program then the one the COE follows, but hopefully this description of this year’s operation will help provide an understanding of the complexity of operating Albeni Falls in a manner that prevents flooding while maximizing the other competing uses of Lake Pend Oreille.
Thanks for reading, and as always, feel free to contact me. My home address is P.O. Box 112, Dover, Idaho, 83825, by e-mail at geskridge(at)coldreams.com and phone at (208) 265-0123.