New reservoir flow plan a win for state

Lake Koocanusa and Hungry Horse Reservoir will drop 20 feet below full pool over the next couple months, but it will happen in a way that has been long fought for by the state of Montana.

And starting next summer, the reservoirs can be drafted only 10 feet below full pool, except in drought years, under a revised federal biological opinion that came out on June 6.

"That's a big win for us," said Brian Marotz, hydropower mitigation coordinator for Montana Fish, Wildlife and Parks.

The best part of the dam operations, Marotz said, is the gradual nature of the "flow augmentation" releases that are intended to provide more water for migrating salmon in the lower Columbia River basin.

"What we're shooting for is a 20-foot draft … and we're trying to keep the discharge level and flat and we're going to stretch into September," Marotz said.

That's a big change from the way flow augmentation used to work. For years, water was released over a short period. There were rapid drafts in the reservoirs. And that resulted in "dual peaks" - in the spring and late summer - on the Kootenai and Flathead rivers. River flows would drop dramatically at the end of August.

The ecological impacts were substantial. Reservoir shorelines were de-watered at a time when the warmer, shallower waters are most biologically productive.

Riverbanks would rapidly rise, creating shallow shorelines with little or no insect production for juvenile fish, and then they would fall before that production could be generated.

The gradual releases, Marotz explained, "make the reservoirs more productive and because the rivers aren't going to be bouncing all over the place, that will make them much more productive."

Most importantly, the gradual releases will be extended into the end of September, the tail end of a short three-month growing season for bull trout and cutthroat trout.

The old operations essentially cut off one third of that growing season, Marotz said.

Over time, the state developed convincing evidence supporting the environmental damage caused above and below the dams, and challenged the biological benefits of flow augmentation downstream. The releases from Montana provide a barely detectable difference in flows on the lower Columbia.

Yet, the state of Oregon and organizations that back salmon recovery have been persistent in demanding the continuation of flow augmentation. The National Wildlife Federation and Oregon have filed a notice of intent for another court challenge of the biological opinion, with specific interest in Montana dam operations.

Marotz, however, is confident in the scientific evidence supporting the new operations at Libby and Hungry Horse.

Reporter Jim Mann may be reached at 758-4407 or by e-mail at jmann@dailyinterlake.com