A surveyor walks on the Swan Lake dam near Ketchikan. (Photo courtesy of the Southeast Alaska Power Agency)

Hydroelectric reservoirs in Southeast Alaska are rising this month with the last of the remaining snow melt and some significant rainfall. However, hydro operators caution those lakes are still a long way from full.

The wholesale power provider Southeast Alaska Power Agency, or SEAPA, generates electricity at Tyee Lake near Wrangell and Swan Lake near Ketchikan. SEAPA CEO Trey Acteson said those projects have rebounded a little with recent rainfall.

“Well they’re improving a little bit obviously but the weather forecast is still saying dry over the next ten days,” Acteson said during a recent interview in Wrangell. “We’ll take whatever we can get but it’s going to take a while to restore the reservoirs.”

An inch of rainfall typically raises Swan Lake by one foot and Tyee Lake by two feet.

The two mainland lakes are at different elevations. Swan is full when that reservoir’s surface reaches 345 feet above sea level. As of Wednesday June 19, that lake had reached 299.9 feet. It’s up 20 feet from a low this winter when generators were shut off.

Tyee is full at 1396 feet. It has topped 1309 feet. That project was all but shut off in late February after dropping to a low over 50 feet below its current level. Both those hydro plants were turned back on after rebounding earlier this spring.

The region is experiencing an ongoing drought dating back to 2017. Typically the two lakes refill during the spring and fall. And despite recent rains, Acteson is hoping for more.

“Well we’re right around kind of where we were last year at this time which was low,” he said. “But one thing that you have to remember, a lot of people forget, is that Tyee, the northern communities need about 200 feet in that lake to make it through the year and the lake only holds 150. So it’s got to get some replenishment throughout the year, in order to serve that whole load.”

The average inflow at Tyee is 250-350 feet of rainfall and snowmelt each year. And interruptions to power sales are impacting the wholesale power provider’s bottom line. SEAPA’s revenue from power sales is over two million dollars below last year’s at this time.

SEAPA in 2016 raised capacity of Swan Lake by 15 feet, or about 25 percent. It also built a transmission line in 2009, to send power between the two projects. The agency hasn’t sent power from Tyee Lake to Ketchikan since last September and may not for the foreseeable future.

June Leffler in Wrangell contributed to this report. This story has been corrected for the time frame for the hydro outage this winter.