The good, bad and ugly of aquatic invasives

DOVER — There is an ample amount of good news about the control of aquatic invasive species in the Pend Oreille basin, but its marbled with some streaks of bad and the downright ugly.

In the realm of good, it appears that last winter’s deep drawdown did a good job at killing off Eurasian milfoil, according to Idaho State Department of Agriculture officials.

“We have excellent milfoil control in that drawdown zone so I don’t anticipate major milfoil issues in areas that were exposed,” Tom Woolf, ISDA’s aquatic program manager, told the Idaho Lakes Commission last week.

The state plans to survey the lake this month and target high-use areas for treatment later in the season.

Woolf said Boyer and Riley Creek sloughs are likely to be treated this season. Non-herbicide control methods are also planned for the City Beach area.

There’s also good news on Priest Lake.

“Priest is a great success story for milfoil management, I believe, because we’ve taken it from an herbicide-treatment project down to the point where we’re seeing individual plants, identifying them and removing them,” Woolf said.

The basin, meanwhile, appears to be free of quagga and zebra mussels, thanks in large part to the state’s mandatory boat inspection station program.

More than 13,000 inspections have been done statewide since February.

“To date, we’ve intercepted eight mussel-fouled vessels this season. That brings us to 113 vessels since the program’s initiation,” Woolf said.

Of particular concern is the discovery of mussels in Lake Powell last year. Woolf said it’s common for boaters to bounce between that lake and Lake Pend Oreille.

The state will be dragging some fine-meshed plankton nets through Lake Pend Oreille this summer to see if there are any mussels at microscopic life stage.

The bad and ugly news involves flowering rush, which was discovered in the Clark Fork Delta in 2007. It’s now found throughout the lake, especially along northern shores.

Bonner County, ISDA, the U.S. Army Corps of Engineers and the U.S. Fish & Wildlife Service have been conducting dry-ground testing on hand pulling, herbicides and bottom barriers. But none of the methods have proven successful in curbing flowering rush.

As a result, the state is consulting with Dr. John Madsen, an expert on flowering rush, to find a control method.

Woolf projected an image of flowering rush badly clogging an area in the delta.

“This is a sign of things to come in the lake if we don’t start to chip away at this stuff,” he said. “It’s really going to be an issue in the coming years in Pend Oreille.”