Wild Ones Native Plants, Natural Landscapes

Aquatic, Near-Shore and Riparian Habitat Quality Improvement Projects
Stroebe Island Marsh, Lower Fox River
James Havel • NES Ecological Services

 

Stroebe Island Marsh

The 16 acre project area, located on the west side of Little Lake Butte des Morts, is currently comprised of deep and shallow water marshes bordered by hardwood, floodplain forests. Due to development along the Fox River, much of the west shore habitat has been destroyed. Therefore, the presence of this wetland complex is very important to regional wildlife and that is why NRDA and WI Stewardship funding was granted to purchase the property. However, preservation by itself will not ensure the presence of a pristine wetland capable of supporting diverse habitats and a variety of wildlife species. To fully compensate for the years of environmental damage that has occurred throughout the Fox River system, restoration and maintenance activities must also be conducted. Throughout the last several decades, anthropogenic activities from the surrounding urban setting have impacted water quality and floral diversity within the wetland complex, which has directly impacted wildlife and their habitats. In the future, by conducting several activities at the WILD Center site, Wild Ones will be improving aquatic, near-shore and riparian habitat quality in the lower Fox River area they own and will work with owners of adjacent property to do the same.

1. Wetland Enhancement

The first activity will be the enhancement of the wetland communities. The riparian woodlands require some removal and/or thinning of trees such as box elder. Disturbance has allowed invasive, exotic species to become established and in some cases dominate portions of the wetland complex. Scientific literature indicates a reduction in floral and wildlife diversity when these invasions occur; therefore, in order to increase habitat value within these communities, Wild Ones will eradicate exotic species throughout the 16 acre complex. As these species are reduced and/or eliminated, native forb, sedge, grass, shrub and tree species will be planted to increase floral diversity and foraging opportunities for wildlife. Direct benefactors of these activities will not only be many of the common birds, mammals and herptiles within the area, but also species such as American bittern, blue-winged teal, rusty blackbird, blandings turtles and four-toed salamanders.

The estimated cost per acre to conduct these wetland enhancement activities is $3,650 with a total cost of $21,700 for the Wild Ones site or $217,700 for the entire area. Within this cost is included three years of maintenance to ensure the majority of the exotic species populations are under control before volunteers begin long-term maintenance activities to guarantee project success.

2. Creation of Riparian Buffers

The second activity will be the addition of upland buffers along the wetland in the southwest portion of the project area. Right now, there is an approximate 25 to 50-foot buffer consisting of riparian woodland between the wetland complex and the adjacent disturbed, fallow field and homestead. This buffer provides some benefits in terms of wildlife habitat and water quality protection, but more recent studies indicate that buffers >100 feet in width provide the best protection to the adjacent wetland and value to wildlife. Therefore, Wild Ones will be restoring the current fallow field to an oak savanna community, which will increase the wetland buffer to > 200 feet. Oak savannas were historically common within southern and central Wisconsin including Winnebago County. Compared to the disturbed fallow field, the now rare oak savanna community will have an opportunity to provide habitat for wildlife species of concern such as blandings turtles, red-headed woodpeckers, brown thrashers, field sparrows, and eastern meadowlarks along with many other common species found in the area.

In addition to establishing an oak savanna buffer, Wild Ones will be installing a 25 foot strip of native landscaping between the house and the existing wetland buffer consisting of riparian woodland. This space is currently being maintained as lawn. Although a buffer > 100 feet is preferred, the location of the house limits the amount of buffer that can be installed within this area. The estimated cost to install and maintain these buffers for three years is $23,850.

3. Wildlife Structures

A. Two turtle nesting sites will be located along the eastern edge of the oak savanna. Shoreline development along with the presence of several barriers such as railroad tracks and roadways has drastically reduced suitable nesting locations for turtle species within the area. The nest sites will be sparsely planted with native grasses and maintained annually to reduce weed species. Although many of the turtles species that will use these two areas are common, the intent is to provide blandings turtles with a safe nesting location to help strengthen their local population. If blandings turtles are observed using these sites, their nests will be protected from predators to increase hatching survival.

B. We will investigate the suitability of adding nesting platforms within the emergent marsh for tern species. Forster's and black terns are known to utilize the Little Lake Butte des Morts system, but their use of the Stroebe Island marsh is not well known. Surveys will be conducted during early June to determine use and to decide if strategically placed platforms will attract the birds once they begin nesting. Although these activities are species specific, both terns are species of concern within the region and could use additional assistance to increase nesting success.

C. A specialized concrete box culvert approximately 8' wide and 30' long under Stroebe Island road will be constructed, providing passage for herptiles between the northern and southern portions of the marsh. Currently, many frogs and turtles have to cross Stroebe Island Road to access the different portions of the wetland complex, which seriously threatens their survival. The culvert will have open grates on the road surface that will allow light to penetrate and permit vegetation to grow along an open water channel. The light would encourage use and vegetated strips would allow safer movement of herptiles within the culvert, especially if predatory fish are also using the culvert. This structure would be used in place of one of the additional culverts proposed by the WI-DNR fishery biologists (in project # 6B below). The cost to construct the specialized culvert is estimated at $50,000, the plants and rock material which should be placed within the culvert would be approximately another $5,000. The additional roadwork to complete the installation is included in the estimate of project 6 B. The cost to add the wildlife structures would be approximately $60,000.

4. Installation of Rain Gardens

Rain gardens composed of native plants will be installed between the existing homestead and the riparian buffer. The gardens will treat surface water runoff from the developed part of the site to protect water quality and it will serve as a demonstration site for neighbors. The ability to provide an up-close and personnel look at a functioning rain garden will assist us in educating and persuading neighbors located on Stroebe Island to undertake similar actions. Since they border the eastern portion of the marsh, their actions can directly impact the adjacent wetland. Estimated cost of rain garden installation - $ 6,500.

5. Stormwater Assessment and Abatement Project

The other threat that will be addressed is a point source discharge of untreated surface water runoff into the marsh. There is currently an eroded channel that flows into the southern marsh, located south of Stroebe Road and east of Butte Des Morts Beach Road, which appears to be collecting water from Hwy 41, the afore-mentioned roadways, and several businesses including a rail yard. Based on the condition of the channel, it appears runoff volume and velocities have resulted in increased sedimentation and disturbance to the wetland community. In addition to the sedimentation issue, nutrient and chemical inputs may be adding to the degradation of the system. To determine the extent of the problem, Wild Ones proposes to conduct an assessment of the stormwater runoff within the area, with particular attention being paid to the lands located west of the wetland complex. In this assessment, we will investigate water sources, approximate volumes and quality of water entering the wetland, and potential solutions/alternatives to the problems. This investigation will include discussions with neighboring residents and businesses, the Town of Menasha, and the Wisconsin Department of Transportation. Although this project will not directly correct all identified issues, it will allow us to begin preparing remediation plans which can be implemented in the near future. If these problems are not addressed, the wetland complex will continue to degrade and along with it a regionally significant habitat for wildlife. Estimated cost for conducting the surface water runoff assessment and planning the abatement project is $7,500.

6. Protecting and restoring pike spawning and nursery habitat

A. A narrow strip of land currently protecting the Stroebe Island marsh from wind and wave action is threatened by erosion. Rip-rap suitable for spawning substrate will be used to shore up this barrier on the south side, and native plant materials will be installed behind the rock to enhance habitats for spawning fish in high water and other species at lower water levels. Some dredging of bottom sediments may be necessary in summer to create optimum depth and slope when the rock is placed on the ice the following winter. Estimated cost $10,000 - 15,000.

B. In order to maximize the value of the marsh for pike spawning, water flow needs to be increased into the northern part of the marsh, maintained by Northeast Wisconsin Land Trust, now limited by the Stroebe Island Road causeway. Engineering for this project and culvert installation by the Town of Menasha will cost about $80,000.

C. After completion of parts A and B of this project, carp barriers may be installed by WI-DNR Fisheries at the southern mouth of the marsh and in the culverts under Stroebe Island Road to keep carp out of the lower marsh altogether. This would prevent erosion and other problems caused by carp from damaging the pike habitat in the marsh. Estimated cost $30,000.

 

James Havel
NES Ecological Services

 

Read the State of Wisconsin Habitat Area Grant Review in PDF format.
Read the NRDA U.S. Fish and Wildlife Service Preliminary Management Plan for the Stroebe Island Marsh in PDF format.

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