Lake Mallalieu Dredging Info

The Lake Mallalieu Association (LMA) is a “qualified lake association”, incorporated and organized under Wis. Stat. Ch. 181 and 281.

A qualified lake association such as the LMA, is a voluntary membership group that possesses no legal authority over public waters, or over lake community members, or over lake properties owned by anyone other than the LMA.

While the navigable waters of Lake Mallalieu and the adjacent Willow River channels are public, both the riparian properties abutting these public waters and the impoundment lakebed properties under these public waters may be and are privately owned. 

The LMA does not own any riparian and/or lakebed impoundment property. The owners of the riparian and/or impoundment lakebed properties of Lake Mallalieu and the adjacent Willow River channels may be viewed at St. Croix County Maps, GIS, and Land Information services. 

The LMA may initiate WDNR permitting processes for a dredging project because Wis. Stat. section 30.20(2) does not require an applicant to be the riparian or lakebed impoundment property owner.

The LMA’s consultant, Stantec, submitted a Preliminary Application to the WDNR in early February 2024 so that WDNR staff could formally determine that sediment sampling would be required. This Preliminary Application remained incomplete as WDNR and Stantec staff engaged in ongoing communications regarding Stantec’s data collection and the proposed dredging project, including: mapping of existing water depths and of existing soft sediment deposits, collecting and analyzing sediment sample cores, and revising the proposed dredging areas and depths. As Stantec gathered further data, the pre-application information was refined and resubmitted to the WDNR for review and further guidance on sediment sampling requirements.

Since Stantec's Dredging FeasibilityStudy recommended a lake drawdown would be a superior alternative to the proposed dredging, the LMA’s Application has not yet been completed. 

If the LMA's Application is deemed complete by the WDNR, WDNR permitting processes require issuing Public Notice of the Application and considering Public Comments on the proposed dredging project, and also may  include holding a Public Hearing, before the WDNR would issue its decision on the Application, 

If the WDNR issues a permit for the LMA’s proposed dredging project, the LMA could  not commence the dredging project without first obtaining authorizations from the owners of the riparian and/or impoundment lakebed properties within the dredging area, and without also obtaining all other required federal, state, and local approvals and permits.

As a qualified lake association, the LMA possesses no legal authority to compel any owner of any Lake Mallalieu or Willow River riparian and/or impoundment lakebed property to undertake or to allow the performance of any dredging activities on their properties.

Most proposed dredging is within the WDNR “Designated Sensitive Areas, Site #1: 83.79 Acres” in northeast Lake Mallalieu and the adjacent Willow River channels.

The WDNR previously has recommended that no dredging or other lakebed removal or modifications should be done within Site #1.

Following the WDNR’s September 2023 field inspection of Site #1, the WDNR did not change either its designation of Site #1 as a Sensitive Area or its recommendations against dredging or other lakebed removal or modifications within Site #1.

Sensitive Areas provide critical or unique fish and wildlife habitat, including habitat for seasonal or life stage requirements, and/or provide water quality or erosion control benefits.

Site #1 includes 70 acres in northeast Lake Mallalieu that extend to the 2-foot depth contour, as well as includes areas around the adjacent Willow River channels that are deep marsh wetlands, sedge meadows, shrub carr, tamarack bog, herbaceous cover, forest growth, or shrub cover.

Site #1 supports at least twenty-four documented species of aquatic plants. Emergent vegetation protects the shoreline and provides important food sources, cover, and fish spawning habitat. Floating-leaf vegetation dampens wave action and provides fish cover. The diverse submerged plant community provides habitat for fish and wildlife, and food sources for fish and waterfowl.

Site #1 provides critical habitat for many endangered, protected, or of concern species, as well as for a wide variety of other invertebrates, fish, amphibians, waterfowl, and wildlife, including:

*An established annual over-wintering location for a growing population of trumpeter swans, who feed on the abundant aquatic vegetation in the shallow ice-free waters where the Willow River flows into Lake Mallalieu;

*Critical habitat for Blanding’s turtles, bald eagles, and ospreys;

*Critical habitat for herons and egrets; many varieties of ducks, including: wood ducks, teal, northern shovelers, mergansers, mallards, golden eyes, and buffalo heads; cormorants; geese; grebes; gulls and terns; kingfishers; owls; pelicans; frogs and toads; turtles; otters and minks; racoons; and deer; and

*Important fish habitat, including: spring spawning and nursery areas for northern pike and crappie; and spring spawning and nursery areas, feeding areas, and cover for small-mouth bass and large-mouth bass.

WDNR records and reports show past chemical treatments for aquatic plant control in northeast Lake Mallalieu have deposited toxic chemicals in lake sediments, including, at least: 

*Arsenic (7,240 pounds or 3.62 tons);

*Endothall (3.6 pounds, plus 4 gallons);

*Diquat (14 gallons);

*2, 4 – D (95 ounces or 1.48 gallons); and

*Silvex (5 pounds).

Arsenic is a broad-spectrum and non-specific herbicide that will kill any aquatic plant. 

Arsenic is a toxic chemical that does not break down. 

Arsenic remains “safe” only so long as it is remains embedded in undisturbed lake sediments.

Previous sediment sampling in Lake Mallalieu has found arsenic to still be present. 

The 2024/25 Stantec Dredging Feasibility Study included collecting several sediment core samples from within the Dredging Study Area and conducting lab analyses to determine levels of arsenic and other contaminants in the sediment samples. Sediment core sampling  and lab analyses done as part of Stantec’s Dredging Feasibility Study did not find arsenic levels in sediment that were high enough to prohibit dredging.

Hydraulic dredging was proposed.

Hydraulic dredging requires water depths sufficient to float a dredging barge, as well as equipment storage and laydown yards, construction access routes, hydraulic dredge hose routes, setups for dewatering the projected 220,000 cubic yards of dredge materials, disposal sites for 220,000 cubic yards of dredge materials, and roadways adequate to handle approximately 22,000 round-trips by large 10-yard dump trucks for transporting 220,000 cubic yards of dredge materials to the disposal sites. 

You  can see a video overview of a hydraulic dredging project in another Wisconsin impoundment at http://www.uppernemahbinlake.com/DredgingProject

Mechanical dredging using heavy equipment to excavate bottom materials would require either water depths sufficient to float a dredging barge, or drawing down the water in Lake Mallalieu by several feet for an extended period so that heavy excavation equipment could operate on the exposed lakebed. Mechanical dredging also would require equipment storage and laydown yards, construction access routes, setups to dewater the projected 220,000 cubic yards of dredge materials, disposal sites for 220,000 cubic yards of dredge materials, and roadways adequate for the approximately 22,000 round-trips by large 10-yard dump trucks to transport 220,000 cubic yards of dredge materials to disposal sites.

Stantec’s 2024/25 Dredging Feasibility Study found that dredging to remove soft sediment deposits from Lake Mallalieu presented very complex issues, and found that dredging would be logistically and financially very challenging to accomplish. Local municipalities have refused to permit the number of heavy truck roundtrips on local roadways that would be required to transport dredge materials to disposal locations; no disposal locations have been secured; the WDNR has refused to permit islands of dredge material in the lake; and a dredging project would cost much, much more than the $2-million state grant to the LMA.

The Preliminary Application to the WDNR prepared and submitted by Stantec on behalf of the LMA Board proposed to dredge up a massive amount of bottom material: 220,000 cubic yards. That is a mass equivalent to a ten-story building covering every inch of a regulation size football field, including the end zones and the sidelines (120-yards long, by 53.3-yards wide, and 103-feet high). 

First, all dredge materials must be dewatered. You can view a video explaining various methods of dewatering at https://www.youtube.com/watch?v=Jz8meWgmPQs. For this proposed dredging project, it's likely that geobags would be used to dewater dredge materials. Geobags likely would be  placed along the shorelines of the dredging areas, and would remain in place for as long as required to dewater the dredge materials, which may be into the year following dredging. You can view photos and videos of dewatering using geobags for another Wisconsin impoundment dredging project at http://www.uppernemahbinlake.com/DredgingProject

After dewatering, dredge materials would be transported to disposal sites. Moving 220,000 cubic yards of dredge materials would require 22,000 round-trips by large 10-yard dump trucks on the roadways from the dewatering sites to the disposal sites.

The proposed disposal method and sites were to spread dewatered dredge materials on nearby farm fields. However, the farm fields closest to Lake Mallalieu and the adjacent Willow River channels are several miles distant. Lake Mallaieu and the adjacent Willow River channels are surrounded entirely by residential properties or undeveloped lands in the City of Hudson, Village of North Hudson, and Town of Hudson.

Stantec’s 2024/25 Dredging Feasibility Study found that dredging to remove soft sediment deposits from Lake Mallalieu presented very complex issues, and found that dredging would be logistically and financially very challenging to accomplish. Local municipalities have refused to permit the number of heavy truck roundtrips on local roadways that would be required to transport dredge materials to disposal locations; no disposal locations have been secured; the WDNR has refused to permit islands of dredge material in the lake; and a dredging project would cost much, much more than the $2-million state grant to the LMA.

The many variables among dredging projects make the length of time and amount of money required to perform a dredging project in a Wisconsin river impoundment like Lake Mallalieu vary widely, but dredging projects are always lengthy and costly.

The timelines and total dollar costs for other similar dredging projects in Wisconsin strongly suggest that the proposed dredging project in northeast Lake Mallalieu and the adjacent Willow River channels would require much more than one year and $2million to accomplish. 

For example, a dredging project to remove about one-twentieth of the proposed quantity of dredge material from the Upper Nemahbin Lake and the Middle Bark River took the Upper Nemahbin Lake Management District from 2011 into 2024 to mostly accomplish, and the bids for hydraulic dredging of only about 11,000 cubic yards of sediment ranged from $632,360 to $1,312,870 (see: “Upper Nemahbin Lake Management District” website at http://www.uppernemahbinlake.com/DredgingProject).

When evaluating the feasibility of any proposed dredging project, all costs of the proposed dredging project must be calculated and considered—and these costs include not just expenditures of time and money, but also community and environmental impacts.

Community impacts of odors, noise, lighting, traffic, and other issues must be taken into account.

The damage to and loss of valued natural habitats and biodiversity must be taken into account.

Stantec’s 2024/25 Dredging Feasibility Study found that dredging to remove soft sediment deposits from Lake Mallalieu presented very complex issues, and found that dredging would be logistically and financially very challenging to accomplish. Local municipalities have refused to permit the number of heavy truck roundtrips on local roadways that would be required to transport dredge materials to disposal locations; no disposal locations have been secured; the WDNR has refused to permit islands of dredge material in the lake; and a dredging project would cost much, much more than the $2-million state grant to the LMA.

Prior to submission of the Preliminary Application for this proposed dredging project to the WDNR, the Lake Mallalieu Association (LMA) Board did not communicate its plans to and collaborate with critical stakeholders who have important interests that would be affected by the proposed dredging project.

Critical stakeholders include:

*All LMA Members;

*Property owners or residents on or within one mile of Lake Mallalieu who are eligible to be LMA Members (Wis. Stat. section 281.68(3m)(a));

*Public users of the public Lake Mallalieu and Willow River; and

*Other interested members of the public.

Critical stakeholders make differing uses of Lake Mallalieu and the Willow River, and critical stakeholders have differing values and priorities regarding what is important to preserve or change about Lake Mallalieu and the Willow River.

In mid-2019, following the replacement of the upstream Little Falls Dam, the Lake Mallalieu Association (LMA) began surveying people using the public boat ramp on Lake Mallalieu.

As reported in the June 2021 LMA Newsletter, that survey data showed:

*59% of those completing surveys used non-motorized crafts on the lake (canoes/kayaks/paddleboards);

*41% came to fish;

*39% commented on the lake water quality; but

*only 7% complained about sedimentation/lake depth.

Boating by the public users of Lake Mallalieu during the years of and after the upstream Little Falls Dam replacement project does not appear to have been impaired or reduced. People fishing have continued to motor their boats in all the same Lake Mallalieu locations; non-motorized boating seems to have increased, with people in canoes or kayaks or on paddle boards frequently floating throughout the lake and continuing up the Willow River channels; and hunters still motor their boats across the lake and up the Willow River channels.

Both homeowners on Lake Mallalieu and public users of Lake Mallalieu complain about Lake Mallalieu’s poor water quality and nuisance algae blooms—it often is gross.

A  report on Lake Mallalieu’s water quality over the period from 1990 through 2023 was made at the May 6, 2024 Annual LMA Members Meeting. Water quality testing data shows that Lake Mallalieu has had consistently poor water quality—with low clarity, excess nutrients, and algae blooms—from 1990 forward. These water quality testing results did not change significantly during or following the 2015 - 2019 replacement of the upstream Little Falls Dam.

While dredging would make the water deeper in some areas of Lake Mallalieu and the Willow River, dredging would not effectively reduce the continuous flow of sediment and excess nutrients that is the cause of poor water quality and algae blooms in Lake Mallalieu.

As described throughout the 2022 Lake Mallalieu Lake Management Plan (2022 Plan), numerous studies and reports have shown that Lake Mallalieu’s water quality is impaired due to upstream nonpoint sources of excess phosphorous, nitrogen, and sediment—primarily runoff into the Willow River from agricultural land.

Lake Mallalieu is an impoundment at the end of the about 70-mile-long Willow River, which has an approximately 182,000 acre watershed area dominated by agricultural land uses. Lake Mallalieu’s waters are replaced about every five to seven days by the flow of the Willow River. The Willow River continuously carries sediment and nutrients in runoff from upstream lands downstream to Lake Mallalieu. Lake Mallalieu’s water quality is almost entirely determined by the effects of upstream land uses in the Willow River watershed, and water quality studies over the past several decades consistently have found Lake Mallalieu’s water to have low clarity and excess nutrients.

Upstream interventions may effectively improve Lake Mallalieu’s water quality and aquatic habitats.

As explained in the 2022 Plan, the Lake Mallalieu impoundment is highly responsive to deleterious changes in the Willow River watershed, and that means Lake Mallalieu also may reasonably quickly recover following remedial upstream interventions.

The $2million grant for environmental management of Lake Mallalieu that was included in the 2023 Wisconsin state budget (2023 Wisconsin Act 19, Section 78) is not restricted to spending on a dredging project.

The 2022 Lake Mallalieu Lake Management Plan (2022 Plan) sets higher priority goals to achieve for the public benefit than pursuing the proposed dredging project in northeast Lake Mallalieu and the adjacent Willow River channels.

The 2022 Plan establishes three ranked priorities:

1. Improve water quality;

2. Improve aquatic habitat; and

3. Address sediment that has been deposited in the Lake. 

The 2022 Plan identifies many interventions that should be made along Lake Mallalieu’s shores or upstream in the Willow River watershed to help improve Lake Mallalieu’s water quality and aquatic habitat.

Now using all or some portion of the unrestricted $2million state grant to implement these interventions would help achieve the two highest priority goals for Lake Mallalieu and for the public good.

Lake Mallalieu Dredging Info works to alert, inform, and engage all critical stakeholders and our larger community regarding the Lake Mallalieu Association Board's proposed projects, so that all important interests regarding the public Lake Mallalieu and Willow River may be considered and taken into account.

Lake Mallalieu Dredging Info is guided by the values of community engagement. social responsibility, and environmental stewardship, 

Lake Mallalieu Dredging Info  hosts a website and a FaceBook page where we timely share accurate and relevant information regarding a proposed dredging project in northeast Lake Mallalieu and the upstream Willow River channels.