Flathead Lake will fully fill, but late summer could pose challenges

Blair Miller

(Daily Montanan) Though the Flathead River Basin currently sits about 1.5 million acre-feet of water below its normal levels for the end of May, a spokesperson for the company that owns the Seli’š Ksanka Qlispe’  Dam told lawmakers Monday the company is confident that Flathead Lake will fill to full pool at least to start the summer.

The Water Policy Interim Committee heard from Zach Hoylman, the assistant state climatologist, on current conditions in the Flathead and how they compare to last year, while Energy Keepers spokesperson Robert McDonald discussed the outlook for the season and the changes the company made during the past two months to try to stave off another year of record-low lake levels.

Last year’s snowpack in the Flathead River Basin peaked the first week of April at just more than 24 inches of snow-water equivalent about a week earlier than normal and stayed there for about two weeks.

But the end of April and start of May of 2023 brought well above-normal temperatures to the region melted off about 7 inches of snow-water equivalent during a two-week period through the first week of May, leading to record-low snowpack levels for the final two weeks of May and leaving Hungry Horse Reservoir and Flathead Lake at among their lowest levels heading into summer.

When the water that melted off and went downstream was not replenished by spring and early-summer storms, the low water levels at Flathead Lake kicked off a political firestorm. Gov. Greg Gianforte and Republican members of the congressional delegation said they were harming businesses and homeowners and pushed the governments and groups that manage water and dams in the Columbia River Basin to raise water levels at the lake.

But the Columbia River Basin Technical Management Team – made up of federal, state and tribal officials from the basin – declined to do so, saying moving water into Flathead Lake at the expense of Hungry Horse would risk the reservoir’s future lake levels as well as protected bull trout downstream of Flathead Lake. They also worried that the forecast El Niño for the 2023-24 winter could mean another year of meager snowpack heading into the summer of 2024.

Though Rep. Ryan Zinke, the Republican who represents western Montana, introduced a bill in November attempting to require the Interior Department to keep Flathead Lake between 2,892 feet and 2,893 each summer, the bill has gone nowhere. And the forecasted low snowpack for the Flathead and most of Montana has borne out.

At the start of May, the water supply forecast from the USDA’s Natural Resources Conservation Service predicted water supply in the Flathead Basin would generally be between 60% and 80% of normal. At that point, the basin’s snowpack was about 5 inches of snow-water equivalent behind where it sat on May 1, 2023.

While a storm brought rain and snow to the area the first week of May, temporarily buoying the snowpack, it has melted off relatively steadily since then. But not nearly as quickly as it did last year.

In the two weeks since, warm conditions have caused the snowpack levels to closely follow those of 2023 in the basin, but the snowpack for May 21 this year now sits 3 inches higher than it did on May 21 last year in the Flathead. However, it still is only in the 28th percentile when compared to the period of record, and just 77% of normal levels.

“The punchline is that we’re missing about 1.7 million acre-feet of snow or water in our mountains out of about 5 million acre-feet, so it’s a pretty large proportion of missing water,” Hoylman told lawmakers. “You can see we’re seeing a really rapid melt event that is similar to 2023. But the difference, of course, is that we’re starting at a much lower baseline; we don’t have as much snow as we did in 2023.”

He said water forecasters were concerned about how that melting snowpack might continue to change water supply forecasts in the month before summer officially starts, in part because about two-thirds of the eastern half of Flathead County is experiencing moderate drought, and the eastern quarter of the county is already experiencing extreme drought conditions.

McDonald, the spokesperson for Energy Keepers, said that in March and April, water managers were worried “it was beginning to look like a possible repeat of 2023.” But the cooler weather and moisture that came in early May helped push off the quick melt-off.

But the company worked with the U.S. Army Corps of Engineers to twice deviate from the Flood Risk Management Plan, in both March and early May, to keep lake levels above the required lowest level of 2,883 feet.

In March, the USACE agreed to allow Energy Keepers to keep the lake at 2,885 feet through April 15, as the Flathead Beacon first reported. Typically, it has to stay two feet lower through April 15 for flood control but can be raised to 2,890 feet by Memorial Day and to full pool at 2,893 feet by June 12.

But on May 2, the USACE agreed to another deviation to the Flood Risk Management plan, allowing the operators to fill the lake to 2,892 feet, a foot below full pool, by Memorial Day on May 27, because of the forecast dry conditions.

But in the past two weeks, water supply forecasts for the full summer, and especially May and June, have been bumped up, McDonald told the committee, giving the company a better outlook in the short term for water levels.

“We are heading for full pool. The projections show we expect to hit that early this year – the likelihood is very, very good,” McDonald said. “I’m sure the forecasters are squinting as I say we’re confident, but it looks like, in a lot of the modeling, the likelihood is high we hit full pool this year.”

The lake sat at 2,890.6 feet as of Tuesday. But McDonald also warned that longer term outlooks don’t look as good for July and August. The Climate Prediction Center is forecast above-normal temperatures and below-normal precipitation for June, July August, and September, as well as continued drought for northwestern Montana.

He said he’s well aware of the public and governmental interests in the lake levels, and Energy Keepers has started publishing weekly updates on lake levels and short-term forecasts on its website and Facebook page so the public has a better understanding of how the lake levels and dam outflows are being managed.

“More people are tuning in, and by looking at numbers and the metrics, people are discovering it and passing it to their friends and able to keep better tabs on what the lake is actually doing,” he said. “…It is an effort, of course, to replace maybe not-quite-accurate conclusions with how it actually operates and the complicated demands and long list of expectations that have to be met and balanced and juggled.”