Lake Minnewashta Zebra Mussel Eradication Work Nears a Successful Completion

Eric Fieldseth, from the Minnehaha Creek Watershed District, reported today that 100% of the Zebra Mussels exposed to the Copper Sulfate treatment in the last 10 days have died. These were mussels placed in contained cages and used to signal the successful completion of the treatment. No further chemical treatment is planned but the containment barriers will remain up for the weekend to allow a little more time in case any zebra mussels outside of the cages were alive. The containment barriers will be removed by Carver County early next week and the launch will be reopened at that time.

Note that beyond the initial 14 zebra mussels found, the MCWD spent two full days looking around the lake with SCUBA divers and snorkelers. No additional mussels were found outside the contained area. Based on the size distribution of the zebra mussels found (varying sizes ranging from 3 mm to 13 mm), and the fact that they were all found in 1 to 2 feet of water directly under the dock at the public access, and we never detected any veligers (baby/immature mussels) through our sampling, we don’t believe there is reproduction occurring in the lake. The best we can do is go off of the facts we have.

Now we really need all of the lakeshore owners to check their docks and lifts as you take them out this fall and carefully look for zebra mussels. If anyone would like to let the MCWD take a look at them as they are taken out, that would be great! Please email Jill at or Eric at if you are willing to let them look over your docks and lifts as they are removed.

The MCWD will conduct more surveys next spring looking for any additional signs of zebra mussels. Let’s hope they find nothing.

Three final points.
First, this was a very rapid and well coordinated effort by a lot of people. Special mention and thanks go to Eric Fieldseth at the MCWD for taking the lead and spearheading this. Speed was very important in this and Eric did an outstanding job.

Second, without the financial contributions of the MCWD (about $10,000), Carver County (about $10,000) and the Lake Minnewashta Preservation Association members (About $15,000) this effort might not have occurred. Without rapid containment and treatment, the results could have been disastrous as that would have allowed zebra mussels to infest broad areas of the lake with negative effects.

Finally, The LMPA members voted two years ago to build up an emergency fund for just such a purpose and thankfully we had it. Now that account is completely empty and we need to refill it. Please consider a generous donation in our fall fundraising campaign to make that happen. State, County and watershed funding on Aquatic Invasive Species efforts unfortunately are being severely curtailed and it will be up to the lake association members to carry a larger load in the future. Feel free to contact our local county commissioners to voice your concerns. Tom Workman,, is our county commissioner and he is a friend of Lake Minnewashta.

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Zebra Mussel Eradication Update from Eric Fieldseth – MCWD AIS Lead

We are 7 days into treatment, and have reached 100% mortality of the zebra mussels samples in the small 0.61 acre area surrounding the access. As of today, we are currently at 36% mortality in the larger, 29 acre site. We expect to see more mortality in the coming days, hopefully reaching 100% by Friday, but no guarantees.

As far as non-target impacts, the Dissolved Oxygen crashed pretty early, there has been a small fish kill composed of a couple pike, several bullheads and some small perch. The majority of the dead fish seem to be bullheads, mostly really small ones. They are not numerous, you have to drive through the water lilies to see them. There are still a lot of fish swimming around, and since we are at 100% mortality in the small area, we cut a few zip ties at a couple seams in the barrier to hopefully allow fish to get out of that area. The native mussels we had in our sample cages are also mostly dead, there is still one alive in the larger area. As far as vegetation, we saw very early impact to Coontail, its mostly gone from the channel. Sago Pondweed and Eurasian Watermilfoil remain fairly abundant.

We’ve had three bump treatments since the initial treatment, with another small bump likely tomorrow. Concentrations seem to be holding fairly steady now. We’ve used 1300 gallons out of the 2100 gallons that were initially ordered so far. We will likely have some left over, I’ll work with the manufacturer on our options for any leftover chemical.

As far as the access reopening, Carver County will make that decision. I think we’ll have a really good idea on how realistic that is in the next couple days.

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Camp Tanadoona Volunteer Day is Saturday September 24th

Tanadoona Volunteer Day
Saturday, September 24
1:00 – 4:00 p.m. at Tanadoona

Bring the family, co-workers and friends to help protect the natural beauty of Tanadoona by improving water quality at and around Lake Minnewashta!

Volunteers will help remove buck thorn, spread wood chips, rake and more to help prepare camp for winter.

With a variety of projects this is a great volunteer activity for families, groups and individuals! We have projects for ages 6 and older. Please register in advance. Follow the link below for more information. Click here to register.

Camp Tanadoona Volunteer Day

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Resident Input Invited at LMPA Board Meeting – September 20, 2016 at 7PM – Gunther’s House 3628 Hickory Road


I. Call to order:

II. Approval of minutes
* Review/approval of last meeting minutes (Steve G)

III. Resident input on agenda items

IV. Reports:
* Financial Update including fundraising and budget (Jim)
* Zebra Mussel treatment status (Steve G)
* CMCW update (Steve A)
* Neighborhood Captains (Scot)
* Communications (Steve G)

V. Unfinished Business:
* Groundwater management (Rick)

VI. New Business
* 2016 Annual Meeting proposal for October
* 2016 Calendar (All)
* How to address Algae levels in the lake

VII. Adjourn

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What’s Going on at Roundhouse Park?

Thanks to Chanhassen’s Parks and Recreation director Todd Hoffman, city staff and input from the neighborhood, some great new amenities are being added at Roundhouse Park off of Minnewashta Parkway. A tennis court and pickle ball courts are among those improvements. Here’s a link to the Roundhouse Park Improvements

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Zebra Mussels Discovered in Lake Minnewashta – Rapid Response Plan Update

As you may know, on August 18th, during a routine weekly check, four zebra mussels were found under one of the two piers at the Carver Parks boat launch on Lake Minnewashta. The following day, a team of people inspected a broader area of “Little Minnie” as well as 8 other areas of the lake. Ten additional zebra mussels were found near the launch but none were found beyond the public access.

A plan of attack has been developed with the Minnehaha Creek Watershed District, Carver County, the Department of Natural Resources and the Lake Minnewashta Preservation Association. The MCWD’s Aquatic Invasive Species Program Manager, Eric Fieldseth, is serving as the leader of the effort. Here is where we are at:

1. Carver Park’s Boat Access #1 was closed and Boat Access #2 was opened.

2. Two containment barriers were purchased and installed by Carver County in Little Minnie by Boat Launch #1.

3. An eradication plan was developed and approved by all parties including the DNR. A well known copper-based algaecide, Earthtec QZ, will be applied in a 0.5 parts-per-million dosage. Click on for more information. Treatment is tentatively scheduled to begin next Tuesday, September 13th at 10:00 am. Additional treatments will occur throughout the duration of the project as needed to maintain our desired concentration. Duration of treatment is predicted to take between 8 to 14 days depending upon zebra mussel mortality results. MCWD staff will be monitoring the treatment and coordinating applications throughout the project.

4. Once the zebra mussels have been eradicated, remove the containment barriers and reopen Boat Access #1.

5. Continue monitoring Little Minnie as well as our 10 existing monitoring stations around the lake to assure that zebra mussels are fully eradicated. Residents who currently have monitoring plates in place should check them immediately and report any findings to the MCWD and Steve Gunther.

A lot of people have been working very well together in making this happen. The very capable leaders of the team are Eric Fieldseth from the Watershed District and Drew Dickart from Carver County’s Aquatic Invasive Species program. The LMPA offers them and the entire team our hearty thanks.

As to funding for this project, the MCWD, Carver County and the LMPA each are sharing in the costs. As of this writing, the county has spent $10,000 and committed another $5,000, the MCWD has committed about $10,000, and the LMPA has committed $15,300. Eric Fieldseth had good results convincing the material supplier to cut our costs significantly.

Stay tuned and when a request for donations is made, please give generously.

Keep in touch – Be sure to give us your email address so we can add you to our electronic newsletter distribution. Or check our website at And join our Lake Minnewashta Preservation Association Facebook group! Or tweet with us @lakeminnewashta. Or email us at

Please don’t hesitate to contact me if you have questions or comments about things we are or are not doing. Thanks for reading and thanks for your support!

Steve Gunther
President, Lake Minnewashta Preservation Association

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