7a. City Policy Re Eurasian Water MilfoilCITY OF 7c<,
CHANHASSEN
690 COULTER DRIVE • P.O. BOX 147 • CHANHASSEN, MINNESOTA 55317
(612) 937 -1900 • FAX (612) 937 -5739
MEMORANDUM
TO: Don Ashworth, City Manager
FROM: Phillip Elkin, Water Resources Coordinator
DATE: July 9, 1997
SUBJ: City Policy for Control of Eurasian Water Milfoil (EWM)
For the past three years the City of Chanhassen has contributed funds to the Lake Minnewashta
Preservation Association for the purpose of controlling Eurasian Water Milfoil (EWM). The
City' Surface Water Management Utility matched funds provided by the Minnesota Department
of Natural Resources. This year, because the City was concentrating its efforts on water quality
projects for Lake Minnewashta, I decided not to contribute to the Lake Minnewashta EWM
program, because of the cost of these projects. Representatives from this association are not
pleased with this decision and fear losing City contributions in the future.
In addition to Lake Minnewashta, representatives from Lotus Lake, Christmas Lake and Lake
Riley have approached the City asking for assistance in their EWM treatment efforts.
Currently the City has no formal policy on contributing to lake association efforts to treat EWM.
The only reference I can find to this practice is the attached memo to council dated June 24,
1994. The memo references a EWM fund, which is now the Lake Management portion of the
City budget. This money from the Surface Water Management Plan is targeted for informational
material for residents, lake management plans, and water quality testing.
I have listed several concerns about continuing to operate in this manner:
• The City drafted lake management plans for all of the lakes affected by EWM. None of the
support suggested by these plans are being used.
• As the DNR's contribution declines, lake associations will look to the City to make up the
difference.
• The City does not contribute to other homeowners associations for control of exotic species.
• This policy is contradictory to recent efforts by the City to prevent the use of herbicide in
other wetlands.
07/09/97
Page 3
• Attempts to treat EWM in this manner are short term actions, that will use as much money
that is thrown at it.
• Constant use of herbicide kills native plants and does not give native plants a chance to
compete with EWM.
• Continued use of 2 -41) may affect the long term quality of lake water and its ecosystem.
MnDNR
The Minnesota Department of Natural Resources is the governing agency for any activities below
the ordinary high watermark (OHW) for waterbodies of 10 acres or more. They have conducted
public education programs and lake monitoring to raise awareness and prevent the spread of the
weed.
Surveys are conducted annually to find lakes infected with EWM. Once the a lake is found to
have EWM, the DNR conducts its own eradication efforts by spraying infested areas with 2 -41).
The DNR will continue this effort until EWM has been identified in 10% of the lake's littoral
zone. At this point the DNR has determined that the plant cannot be eradicated and will stop
chemical treatment to allow the weed to run its course.
A portion of each boating license sold is put into a fund for EWM management. This money is
set aside for lakes infested with EWM and divided to each lake depending on size. It is this
money that the lake associations are using for EWM treatment.
Status of EWM in Chanhassen Lakes
Lake Minnewashta
The Lake Minnewashta Preservation Association has been active in raising close to $20,000
annually for the past few years to conduct lake -wide applications of 2 -4D.
Lotus Lake
EWM is a problem along the shore line to depths of approximately 4 feet, but because water
clarity of the lake is so poor, it does not grow to the surface in deeper waters. A lake association
has been inactive until last year, when they were approached by a consultant who offered to
develop a milfoil plan for the lake. Since then, the group has been organizing efforts to combine
individual property owner's treatments. Because milfoil is not a problem in areas eligible for
DNR funding (see attachment), the only areas where DNR funds could be used are on public
park property. Chemical treatment of EWM is not endorsed or permitted by City Parks and
Recreation staff.
Lake Riley
EWM has been a problem in the past, but in the last two years the lake has not been clear enough
for EWM to be a nuisance.
07/09/97
Page 3
Lake Ann
The DNR detected EWM near the public access in 1995 and has been attempting to eradicate the
weed with applications of 2 -41) each year since.
Christmas Lake
Same status as Lake Ann. The lake has areas of EWM detected in 1995, which the DNR is still
treating with hopes of eradication.
Lake Lucy
EWM has not been detected.
Lake Susan
EWM has not been detected.
Rice Marsh Lake
EWM has not been detected
Recommendations
Because there is no evidence that treating with 2 -41) provides long term eradication of the weed,
I would recommend that the City discontinue providing money for this short term treatment
program. This action does not prevent the individual lakeshore homeowner from treating lake
areas adjacent to their property, nor does it prevent associations from using MnDNR funds for
treatment.
I have included some options on how the City Council can act on this issue.
Continue to match DNR funds on eligible Lakes
• Continue to cooperate with existing programs
• Identify high use areas to be treated
• Require updated maps of areas treated each year
• Conduct extensive plant surveys every other year to monitor affects on native species
Discontinue to fund herbicide treatments
• Fund plant inventories and water quality studies
• Allow nature to take its course and learn to compete with EWM
Set a limit on money to be spent by each lake for EWM treatment
• All lakes given a set dollar figure for EWM management
• Conduct extensive plant surveys every other year to monitor affects on native species
• Require updated maps of areas treated each year
Original Memo to Council RE: EWM Funding
MEMORANDUM
TO: Dick Wing, City Councilman
FROM: Diane Desotelle, Water Resources Coordinator
DATE: June 27, 1994
SUBJ: Eurasian Watermilfoil
The purpose of this memo is to inform the council about the actions taken at Lake Minnewashta
concerning Eurasian Watermilfoil (EWM). Minnewashta Lake has been heavily impacted this
year with EWM. Lake Minnewashta has approximately 370 acres of littoral zone (water depths
15 feet or less). A significant portion of this area has EWM (attachment) and the City has
received numerous calls from lake shore residents concerning the issue. Randy Schwoerer and
Tom Huntington have helped to coordinate meetings for the homeowners and associations to
gather feed back on the issue.
Over 40 people were present at last Wednesday nights meeting and a second meeting is
scheduled for this coming Thursday. The group decided to get bids from two companies for
treating the lake with 2, 4, D, an herbicide known to be effective on EWM. The citizens thought
this would be a short term solution to the problem.
The City has a 1994 EWM fund of $10,000. The 1994 state funds for managment of EWM in
Lake Minnewashta is $2,384: The City has offered to match the state funds for Lake
Minnewashta. These monies are intended to be used at highly impacted areas to test the process
and to alleviate the short term problem. Additional monies from the City fund will be directed
toward a lake management plan that will address the short term and long term goals for the lake.
Individual p ro lake given to the lak shore this winter. Similar goals a an re set education and ,
information p program g
Riley, Ann, Lucy, Susan, and St. Joe.
There are different philosophies and theories on the management of EWM, but no clear answers
of the best solution. Attached is some information on EWM and the options for managing the
plant. I am available to help coordinate the management efforts and provide technical assistance
on this issue.
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Areas on Lakes Eligible for MnDNR Funding
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In this area the cost of control of milfoil
may be reimbursed by the Minnestoa
Department of Natural Resources.
Issuance of a permit for use of herbicide
in this area will NOT require either
a.) signal M of all owners of nearby
property or b.) payment of a fee.
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. • . • • by the DNR
In this area the cost of control of milfoil will
NOT be reimbursed by the Minnestoa
Department of Natural Resources.
Control may be done either by owner
of adjacent property or an organization
such as i Wm association, conservation
district, or other total unit of government.
Issuance of a permit for use of herbicide
in this area will require a.) signatures of
all owners of adjacent property and
b.) payment of a fee.
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In this area the cost of control of milfoil will
NOT be reimbursed by the Minnestoa
Department of Natural Resources.
Control may be done either by owner
of adjacent property or an organization
such as i Wm association, conservation
district, or other total unit of government.
Issuance of a permit for use of herbicide
in this area will require a.) signatures of
all owners of adjacent property and
b.) payment of a fee.
Recommendations From Lake Management Plan
Objectives: In a cost effective manner, develop and implement a program that manages all
aquatic plants, including Eurasian watermilfoil to optimize water -based recreation (boating,
sailing, skiing), maintain the fishery, and improve lake water quality by reestablishing native
aquatic plants and reducing algae blooms.
Techniques and Tools: The management approach will consider six methods for
managing Eurasian watermilfoil. They are:
1. Herbicides
2. Mechanical harvesting
3. Small-scale maintenance techniques
4. Natural forces
5. Combination of harvesting and herbicides (tentative)
b. Lakescaping (upland)
Basis for Using Various Methods
1. Herbicides: Overall philosophy is judicial use of herbicides. Herbicide of choice is
Aquakleen (2,4 -D). Herbicide would be used in nearshore areas, in patches where milfoil is
the dominant plant. Used in areas that require a quick knockdown. At the present time, we
will pursue alternatives to herbicides.
2 Mechanical Harvesting: Overall philosophy is to cut the minimum acreage needed to
produce and maintain a reasonable degree of boat access to lake users. Approach is to use
the harvester for cutting corridors. Harvesting is not generally used for cutting large
expansive areas (too slow, too expensive).
3 Small -scale Maintenance Techniques: General philosophy is that nearshore areas can be
custom - managed using a variety of small -scale techniques such as cutters, rakes, drags, scuba
divers, and herbicides. Milfoil control from 0 to 4 -feet of water will be the responsibility of
property- owners: Work can be done by residents or it can be contracted.
4. Natural Forces: General philosophy is that natural forces such as weevils, moth larvae,
other insects, and microorganisms will some day keep excessive milfoil growth in check. It
could happen in 10 years or may take longer. A widely held view by researchers is that the
less an area is disturbed, the quicker these forces can become effective. Therefore, a
number of areas with milfoil in Lake Riley will be left undisturbed, allowing natural
processes to evolve into natural controls.
S Harvesting combined with Herbicide Use: (tentative) General philosophy is that
harvesting will injure the milfoil plant and as the plant works to repair damage, it will
rapidly be taking up nutrients and other compounds. It would also take up herbicide, and
may be more vulnerable compared to a non - injured condition. Advantage of this technique is
herbicide is applied after milfoil has come up (only treating known problem) and can be
targeted. This approach is experimented and will be used if there is interest.
6. Lakescaping_ Reestablishment of a native plant community is a long -term goal for Lake
Riley. We will test the feasibility of reintroducing native plants to Lake Riley using the help
of lake residents. This could be done in conjunction with homeowners landscaping their lots
to emphasize native plants -- groundcover, wild flowers, shrubs, and trees. The combination
of aquascaping and natural landscaping is called lakescaping.
Details of Implementation Program
A lake map showing milfoil control areas is shown in Figure 1. A breakdown of milfoil
control by technique is shown in Table 1.
Table 1. Eurasian watermilfoil control program: proposed acreage to be treated and estimated costs.
1JNK permit application costs
b cost is borne by lake residents
cost for lake side demonstration and handout materials
' 75/25 cost share with city contributing 75% and homeowners contributing 25%
Acreage
Corridor's
Cost per
Cost per
Other
Total
Addressed
Created &
Acre of
Technique
Costs
Costs
Maintained
Unit Cost
1. Herbicides
0
--
200 /ac
0
0
2. Mechanical
5
240 /ac
1,200
100`
2,100
Harvesting
(1" cut)
5
160 /ac
8,000
(2' cut)
3. Small -scale
3
--
Ob
0
1,000`
1,000
Techniques
4. Natural
50
--
0
0
0
0
Forces
5. Harvesting
?
?
240 /ac
?
--
?
plus
(harvesting)
Herbicides
200 /ac
?
--
(herbicides)
6. Lakescaping
several lots
--
600 11ot'
3,000
3,000.
--
--
--
--
--
2,000
2,000
(monitoring)
Totals
58+
--
--
--
8,100
1JNK permit application costs
b cost is borne by lake residents
cost for lake side demonstration and handout materials
' 75/25 cost share with city contributing 75% and homeowners contributing 25%
Herbicide Use
At the present time, we are not planning open lake herbicide treatments. A number of
individual lake residences will probably continue to use herbicides. Application should occur
when milfoil is actively growing. Permits from the MnDNR will be secured by the
individual homeowner. Application will probably occur in June. Approximately 3 acres will
be treated.
Mechanical Harvesting
Approximately 5 acres of milfoil would be harvested in a first cut, and the same 5 acres in a
second cut. Two days of mechanical harvesting have been budgeted for the first cut. We
have assumed 3 hours /acre for milfoil harvesting. Assuming a 9 -foot wide cut by the
machine, one acre (43,560 square feet) of harvesting will produce a 4,800 -foot corridor. We
are estimating that approximately 24,000 feet (roughly 4.5 miles) of corridor could be cut in
a 2 -day period. A corridor perpendicular to shore will be made for about 100 residences.
Perpendicular corridors will range in length from 300 to 500 feet and will go from the end of
a dock out to open water. Residences that get corridors cut will be staked at shore so the
harvester will know where to cut. These perpendicular cuts will measure a total of about
24,000 lineal feet. Locations are shown in Figure 1.
Small -Scale Maintenance Techniques
Approximately 3 acres of aquatic plants dominated by Eurasian watermilfoil could be
removed with this method. The area of control is the nearshore areas in front of lake
residences. Removal would occur in water depths from 0 to 5 feet. It is estimated that 50
residents may participate and would remove an average of 2,500 square feet (0.06 acres) for
a total of 3 acres. A variety of techniques are available. If non - chemical means are used,
residents don't need a MnDNR permit if less than 2,500 square feet of plant area is removed
(assuming no emergents are removed).
A good approach for long term control is to first use a cutter to cut milfoil, then rake it out
of the water and then run a drag over the area to dislodge root crowns. A lakeside
demonstration day will be organized and could be held in conjunction with the Association
meeting on June 17. Various techniques would be demonstrated. Homeowners would bear
the cost for work done in the nearshore areas. They could do it themselves or hire
somebody.
Natural Forces
This technique lets nature do the work. Large areas will be left undisturbed and we will
monitor what occurs in these patches.
Harvesting with Herbicide Application
For high use corridors in Lake Riley, harvesting followed by a herbicide application could
be tested. This is somewhat of an experimental approach and not more than one miles of
corridors would be tested. The harvester would first make a cut, creating either a parallel or
perpendicular corridor. Within a day or two, a herbicide application will be made at a rate
of 80 to 120 pounds per acre using Aquakleen
(2,4 -D).
3