Zebras found/Ruth Lake

[Lee Borgersen]

Crow Wing County Board: Board funds Ruth Lake AIS treatment

 Sep 23, 2015 

Ruth Lake in Emily will likely be the site of a fifth zebra mussel treatment pilot project by the Minnesota Department of Natural Resources, the Crow Wing County Board learned Tuesday.


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Commissioners approved a request from the Ruth Lake Improvement District to access $5,000 of state-granted funds allocated for aquatic invasive species to help cover costs of the treatment.

Dan Swanson, AIS specialist with the Brainerd DNR office, said an adult zebra mussel was discovered in July along the eastern shore of Ruth Lake by a 15-year-old vacationer. Follow-up dives turned up dozens more adult mussels, confirming the only infestation discovered thus far in a Crow Wing County lake in 2015.

That's the bad news, said Chris Pence, land services supervisor. The good news, he went on, is the mussels appeared contained to the immediate area and further testing indicated there are no veligers present in the lake's waters. The lack of veligers - which are the larvae of zebra mussels - shows it's unlikely the zebra mussels are reproducing, making the lake a prime candidate for localized eradication efforts.

"The issue with this is it is still a pilot project. Success isn't guaranteed in this situation," Pence said. "But from what we know and what's been analyzed and determined out there at this site, it seems to be a good fit."

Pence pointed to a similar situation at Rose Lake in Otter Tail County, where a 2011 copper-based treatment appeared successful likely because it was caught early.

Commissioner Paul Thiede, who serves on a statewide AIS committee, said he was concerned with the amount of time that's passed since the initial discovery.

"One of the frustrations I have is (what) we've been talking about with these AIS dollars is rapid response," Thiede said. "July to October ain't no rapid response in my mind."

As the person leading response, Swanson said, "If you want to blame anybody on rapid response, I'm the guy."

He went on to share a detailed timeline with the board of everything done at the site since July 13, including multiple dives at various locations throughout the lake, a second discovery by a vacationer in August at the original site and three series of veliger testing. Initially, the extent of the infestation was unclear, Swanson said, which made the scope of response difficult to determine.

"We've got to see if there's more before we treat," Swanson said. "It maybe doesn't sound rapid, and it really isn't, but we got the hang-up where we weren't finding anything else."

Commissioner Rachel Reabe Nystrom thanked Swanson for his response, noting she initially sympathized with Thiede's remarks before hearing Swanson's explanation.

"You have just laid this out in a very compelling way how difficult it is," Nystrom said. "The series of steps that you've taken, to me, sound very appropriate."

Swanson said the steps were based upon a protocol developed for response to private AIS treatment projects. This protocol was developed following the unsuccessful treatment of Christmas Lake west of the Twin Cities last winter. Although initial results appeared to kill all the zebra mussels in the lake, adult specimens were located outside the treatment zone months later.

"We kind of learned from that that they probably should have done more monitoring," Swanson said.

While attending an AIS conference at the University of Minnesota last week, Swanson said he received positive feedback on the amount of research done on the lake.

"They said, 'Wow, you've got a lot more data than they did on Christmas Lake before they treated it,'" Swanson said.

The funds approved by the board will cover one-quarter of the cost of treating the 500-by-250-foot area. The lake improvement district is in the process of raising the additional $15,000 needed to cover costs.

Treatment is expected to begin in early October pending final DNR approval.

 
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Dan Swanson, AIS specialist with the Brainerd DNR office, said an adult zebra mussel was discovered in July along the eastern shore of Ruth Lake by a 15-year-old vacationer. Follow-up dives turned up dozens more adult mussels, confirming the only infestation discovered thus far in a Crow Wing County lake in 2015.


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