Starry Stonewort


Starry Stonewort confirmed in Pope County’s Lake Minnewaska

August 21, 2017

The Minnesota Department of Natural Resources has confirmed the invasive algae starry stonewort in Lake Minnewaska in Pope County. This is the second new confirmation of starry stonewort in a Minnesota lake in 2017. 

DNR invasive species specialists confirmed an abundant growth of starry stonewort among native aquatic plants in the narrow Lake Minnewaska marina off the main body of the lake. Additional searches are being conducted to determine whether it is anywhere beyond the marina.

Treatment options are being considered. Starry stonewort has never been eradicated from any U.S. lake, but treatment can help ease lake access and water-based recreational activities.

There are now 11 lakes in Minnesota where starry stonewort has been confirmed. Two were confirmed in 2015, seven in 2016, and two this year. It has been present in at least some of these lakes for several years, rather than being spread to many lakes in a just a year or two.

Since the first case was confirmed in 2015, all but one have been reported in the month of August, when the telltale star-shaped bulbils are most abundant and visible. Now is the best time of year to look for it. Information on how to identify starry stonewort can be found on the DNR’s website, and any suspicious plants should be reported to the DNR.

Starry stonewort is an alga that can form dense mats, which can interfere with use of a lake and compete with native plants. It is most likely spread when fragments have not been properly cleaned from trailered boats, personal watercraft, docks, boat lifts, anchors or other water-related equipment.

Invasive Weed Starry Stonewort Reaches 1 More Minnesota Lake

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Grand Lake - Starry Stonewort 8-15-17

MN DNR Press Release 8-15-17

Catch me if you can: Divers hope to clear Grand Lake of starry stonewort before it spreads

Starry Stonewort found on Lake Sylvia in Wright County

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Lake Sylvia - Stary Stonewort

All of Sylvia’s costs for SS treatment this year come from association funds except for a $6K matching grant (their limit) from Wright Soil & Water Conservation District. 

9-6-17:  This morning they completed their third of four planned starry stonewort treatments.  The good news is in surveying the previously treated areas, the new growth that was found was a relatively small quantity without a lot of mass.  The treatments appear to be very effective by continuing to treat any new growth found.  It seems obvious that treating an area once and thinking that was all that was needed would not be effective.  Repeated searching and treatment of any new growth is mandatory to staying in control.

7-27-17: Two pieces of good news from Sylvia: the SSw growth appears to have been slowed and somewhat contained.  As of yesterday, the next treatment at Sylvia will take place on Monday starting from the Sylvia public ramp.

News & Events MAY 3rd

Local-State Collaboration Results in Starry Stonewort Success

Grand Lake in Stearns County

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DNR News MAY 24th

Make safe boating top priority on Memorial Day weekend

Water remains dangerously cold, life jackets a necessity Memorial Day weekend signals the start of the summer boating season, but boaters should keep in mind water temperatures remain spring-like. The Minnesota Department of Natural Resources urges b...

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