6.10 Section 3 - Management of AIS Present in the District

Invasive plant and animal aquatic species are present in differing numbers and locations throughout the District.  This section of the Plan identifies the species known to be present and the approaches that will be followed in managing them.

AIS PLANTS

1.      Brazilian Elodea        (Status in Minnesota:  Watch)                       

Where it is present

  • Powderhorn Lake

Brazilian Elodea was found in Powderhorn Lake in 2007, and treated with an herbicide in 2009 with the goal of eradicating the plant.  It has not been noted since, but it may still be present.  It is thought to have been introduced via an aquarium dump.

Determine infestation level of confirmed water bodies

A survey should be performed to determine if Brazilian Elodea is still present, and at what frequency it is found in the water body.

If Brazilian Elodea is still present

Consult with Minneapolis Parks and Recreation Board (MPRB) and the DNR to determine if action should be taken, or if the risk of spread from the lake is low enough that only monitoring the plant is warranted.

Confirm presence/absence of Brazilian Elodea in water bodies where data are missing

The comprehensive inventory of District waterbodies that will document the presence of AIS should reveal any new infestations of Brazilian Elodea.

Periodic, ongoing monitoring in all waterbodies in the MCWD

All water bodies in the District will be periodically monitored for Brazilian Elodea, with more frequent monitoring for Powderhorn Lake.

2.      Curly-leaf Pondweed (CLP)           
(Status in Minnesota:  Severe)

Where it is present

Curly-leaf Pondweed is confirmed in nearly every lake with a public boat access in the MCWD; the exceptions are Dutch, Steiger and St. Joe.  Schutz Lake, which has a private access, also does not have CLP confirmed.  It is also confirmed in many other water bodies in the District, totaling 31 in all.  (Refer to the MCWD CLP Map later in this document for the infested water bodies.)

Notable water bodies without CLP

  • Dutch
  • Steiger
  • Schutz

These lakes should receive high priority ongoing monitoring for CLP

Current Research on Curly-leaf Pondweed

The MCWD conducted a five-year study to test the effectiveness of a lake-wide, early-season, low-dose treatment using the herbicide Endothall on Gleason Lake.  It was successful in reducing the population of CLP to smaller, more manageable areas and improved water quality in the lake as well.  A native plant, Coontail, subsequently took over and is now the dominant plant in the lake.  Studies by other researchers using these same methods have successfully reduced CLP populations to smaller, more manageable areas, but improvements in water quality have been highly variable.

Determine infestation level of confirmed water bodies

While the presence CLP is known in waterbodies, information on the extent of the population is not always available.  All current available plant survey data will be analyzed, and any water bodies without data will need to be surveyed.  All factors and variables will need to be assessed, including the cost, likelihood of success, economic importance of water body, any ecological harm that it may be causing and the public use of the water body.  These factors will lead to the determination if containment or control efforts should be performed for CLP in the District.

            If CLP is found to be containable:  The District will address the presence of CLP at       this level in accordance to the Element 2 – Containment/Eradication strategies and       actions in Section 2 of the AIS Management Plan.

            If CLP is determined to need long-term control management:   The District will           address the presence of CLP in this situation in accordance to the Element 3 – Long-    Term Control (Management) and Removal strategies and actions in Section 2 of the AIS        Management Plan.  

Confirm presence/absence of CLP in water bodies that we are missing data

In water bodies where a recent survey has not been performed, a plant survey will be needed to evaluate whether CLP is currently present or not.  This will be part of the inventory of water bodies in the District to document the presence of AIS.

Periodic, ongoing monitoring in all water bodies in the MCWD

All water bodies in the District will be periodically monitored for CLP.

3.      Eurasian Watermilfoil (EWM)        (Status in Minnesota:  Severe)

Where it is present

Eurasian Watermilfoil is confirmed in every lake with a public boat access in the MCWD, except for Lake St. Joe, a very small, low-use lake.  It is also present in many other water bodies without a public access, and is confirmed in a total of 27 such waterbodies in the District.  (Refer to the MCWD EWM Map later in this document for the infested water bodies.)

Notable water bodies without EWM

  • Gleason Lake
  • Mooney Lake

These lakes should receive high priority ongoing monitoring for EWM.

Current Research on Eurasian Watermilfoil

In 2012, the MCWD commissioned a biological control study for EWM by stocking high numbers of an aquatic milfoil weevil (Euhrychiopsis lecontei) in three water bodies of the MCWD.  Due to unsuitable seasonal conditions, the study was curtailed and only a small area on one lake was stocked.  A small reduction in stem density and biomass of EWM in the treatment site occurred.  Continuation of this study is currently being assessed by the MCWD.

Determine infestation level of confirmed water bodies

While the presence EWM is known in waterbodies, information on the extent of the population is not always available.  All current available plant survey data will be analyzed, and any water bodies without data will need to be surveyed.  All factors and variables will need to be assessed, including the cost, likelihood of success, economic importance of water body, any ecological harm that it may be causing and the public use of the water body.  These factors will lead to the determination if containment or control efforts should be performed for EWM in the District.   

            If EWM is found to be containable:  The District will address the presence of EWM at   this level in accordance to the Element 2 – Containment/Eradication strategies and       actions in Section 2 of the AIS Management Plan.

            If EWM is determined to need long-term control management:  The District will          address the presence of EWM in this situation in accordance to the Element 3 – Long- Term Control (Management) and Removal strategies and actions in Section 2 of the AIS        Management Plan.  

Confirm presence/absence of EWM in water bodies where data are missing

In water bodies where a recent survey has not been performed, a plant survey will be needed to evaluate whether EWM is present.  The comprehensive inventory of District waterbodies that will document the presence of AIS should reveal any new infestations of EWM.

Periodic, ongoing monitoring in all water bodies in the MCWD

All water bodies in the District will be periodically monitored for EWM.

4.      Flowering Rush

Where it is present

  • Lake Minnetonka and Minnehaha Creek

Current Research on Flowering Rush

In 2011 and 2012, the MCWD led a research project evaluating a hand removal technique on a few sites on Lake Minnetonka.  It was found to be successful in reducing the population in soft sediments, but proved to be difficult in harder sediments. 

Determine infestation level of confirmed water bodies

The MCWD assessed the Flowering Rush infestation in Lake Minnetonka and Minnehaha Creek in the fall of 2012.  Those results will be analyzed and the infestation level will be determined. 

If Flowering Rush is found to be containable on the confirmed water bodies

Lake Minnetonka:  Early indications are that Flowering Rush is containable in Lake Minnetonka; most of the population lies in Crystal Bay, with limited sites in other bays.  These circumstances provide the District with an opportunity to contain Flowering Rush to limited areas on Lake Minnetonka.  Sites in other bays would likely be the initial targets of control, with the goal of containing the Flowering Rush population to Crystal Bay only, and then limiting that population.  Efforts should be evaluated annually to assess the success of the project and to ensure removal methods are reducing the population and not spreading it.  Monitoring would be performed on all treatment sites annually, but since Flowering Rush is known to spread slowly, a focused survey on all areas in the lake known to have Flowering Rush can be done every three years or so to monitor spread.

Minnehaha Creek:  The population of Flowering Rush on the Minnehaha Creek appears to be limited to one area by the Lake Nokomis weir, several areas just upstream of the Minnehaha Falls, and several areas downstream from the Falls closer to the Mississippi River.  These areas should be assessed as to whether flowering rush is causing ecological harm or nuisance in the creek, and whether control measures should be utilized if the opportunity exists.  Other areas of the creek should be assessed as well for Flowering Rush, since the 2012 survey focused on the creek only from the Lake Nokomis weir to the Mississippi River, which is an area that has had a history of Flowering Rush.

Control Methods:

Hand Removal has been the focus of the research performed by the District so far, with success shown in soft substrates.  Given the low density of the Flowering Rush population in Lake Minnetonka and Minnehaha Creek, hand removal is the ideal tool for removal in suitable substrates.

Herbicides have been assessed by other groups in the state, with success in the year of control, but long term reductions are still unclear.  Herbicides would be the likely option for areas not suitable for hand removal, such as harder substrates.

Mechanical removal should be avoided, as it has been shown to spread the plant

Biological control is currently not available for Flowering Rush, but there are groups looking to evaluate possible options.

Confirm presence/absence of Flowering Rush in water bodies where data are missing

In water bodies where a recent survey has not been performed, a plant survey will be needed to evaluate whether Flowering Rush is currently present or not.  This will be part of the inventory of water bodies in the District to document the presence of AIS.

Periodic, ongoing monitoring in all water bodies in the MCWD

All water bodies in the District will be periodically monitored for Flowering Rush.

5.      Purple Loosestrife     (Status in Minnesota:  Severe)

Where it is present

Purple Loosestrife can be found throughout the District, but it has been controlled biologically with some success using a beetle.

Status:  In 2012, there were more reports of Purple Loosestrife being present in the District; the MCWD will continually look into the stocking program of the beetles and monitor infestation reports.

AIS ANIMALS

1. Chinese Mystery Snail          (Status in Minnesota:  Watch)

Where it is present

  • Gleason
  • Grass
  • Powderhorn
  • Lake Minnetonka

It appears the Chinese Mystery Snail is likely common in many lakes, although only confirmed in four locations in the District.  It currently is not a nuisance and has not been known to cause ecological harm.   It is a species that will still be watched and monitored by the District.

2.      Common Carp

Where it is present

Common Carp are confirmed in 29 water bodies in the District, but are likely present in many more.

Current Research on Common Carp

The MCWD is currently developing a research study with the University of Minnesota to study Common Carp in the Six-Mile Creek sub-watershed.  This study will bring a better understanding of carp in this sub-watershed and will lead to a more cost-efficient, long-term strategy to reduce carp numbers in this system.  Other University of Minnesota studies on Common Carp have indicated many variables that need to be addressed to successfully reduce the population.

Common Carp management in other areas of the District

Carp management will only be undertaken by the MCWD if a significant ecological issue is identified.  The District will continue to be involved in research, and apply what is learned to other situations.

3.      Zebra Mussels

Where they are present

  • Lake Minnetonka and Minnehaha Creek

Zebra Mussels were first discovered in Lake Minnetonka in 2010, but were likely present a couple years prior to that.  As Lake Minnetonka is connected to the Minnehaha Creek at the Grays Bay dam, they have since spread to parts of the Minnehaha Creek.

Current Research on Zebra Mussels

Lake Minnetonka:  In 2011, the MCWD initiated a three-year study to assess the Zebra Mussel population on Lake Minnetonka and examine the effects on the water quality and algal community in the lake.  After completing the study in 2013, the MCWD will assess which aspects of the study should be continued and which should be looked at as on-going monitoring.

Zequanox:  In 2013, the MCWD is developing a partnership with the USGS and University of Minnesota to study the effectiveness of a product called Zequanox to control Zebra Mussels in an open-lake environment.  If successful, Zequanox could be the first selective control tool available to water resource managers to manage Zebra Mussels in an open-lake environment.  It would likely not be feasible to control Zebra Mussels on a lake-wide basis with Zequanox, but the product may be a useful rapid-response tool, for control on spot treatments, to slow the expansion rate of reproducing Zebra Mussels at known locations.

Determine infestation level of confirmed water bodies

Infestation levels in Lake Minnetonka are already being studied by MCWD, with the population expanding and spreading west-ward in the lake.  Infestation levels have also been monitored in the Minnehaha Creek and have not been found past the Browndale Dam in Edina as of the fall of 2012.  Zebra Mussels in Lake Minnetonka are widespread and beyond the containment stage.  Zebra Mussels in Minnehaha Creek are being monitored, and if the situation arises where containment is possible to prevent introduction to the Minneapolis Chain-of-Lakes, it will be undertaken.

Confirm presence/absence of Zebra Mussels in waterbodies where data are missing

All of the larger water bodies in the MCWD have been monitored for the presence of Zebra Mussels, and none have been found as of 2012. 

Periodic, ongoing monitoring in all water bodies in the MCWD

All water bodies in the MCWD will get periodic monitoring for Zebra Mussels, with more frequent monitoring for the larger water bodies in the District.  The District will perform or coordinate monitoring, as well as centralizing the collection of monitoring data and reports.

OTHER INVASIVE PLANTS OF CONCERN

The MISAC list of invasive species also lists several terrestrial plants that, while not classified as aquatic, are of concern in wetland habitats.  The following is present within the District:

Reed Canarygrass  
(non-native ecotypes/hybrids)                  
(Phalaris arundinacea)Severe

Other species of concern, but not on the MISAC list of invasive species, include:

European Common Reed(Phragmites australis subspp. australis)
*Narrow-leaf Cattail(Typha angustifolia)
*Hybrid Cattail  (Typha angustolifolia Typha latifolia [Broad-leaf Cattail; native])
Glossy Buckthorn and its cultivars(Frangula alnus; syn. Rhamnus frangula)

* There is disagreement whether these species are native to North America; the Minnesota DNR does not officially consider them to be non-native.