Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Bog in Mead Wildlife Area © DNR Photo

Bog in Mead Wildlife Area
© DNR Photo

October 2009

Workhorse wetlands

The Wetland Gems program shines a light on valuable habitat and pinpoints 100 jewels we should naturally treasure.

Laura England and Katie Beilfuss

Swamp ('swämp) –vt. swamped; (1784) to overwhelm numerically or by an excess of something (swamped with work)
Mire ('mir) –n. (14 c.) a troublesome or intractable situation (found themselves in a mire of debt)
Bog ('bäg) –vi. bogged; (1599) to become impeded or stuck – usu. used with down

How many times have you heard "I can't make it, I'm really swamped?" Or "I'm bogged down with this project?"

Wetlands face an uphill struggle to be recognized and valued in our culture and our lexicon. They're called "lowlands" for both their location and a lack of public esteem. It's part of the reason the Wisconsin Wetlands Association launched a program to highlight their unique benefits and promote reasons to protect, conserve and restore these natural treasures.

Last May, the association designated 100 Wetland Gems in Wisconsin to showcase examples of the wetland riches that historically made up nearly a quarter of Wisconsin's landscape. Most of the gems were easy to pick. Sixty-four of these 100 sites are already owned outright or in part by the Department of Natural Resources. Seventy-seven of these properties are already designated as State Natural Areas because they preserve unique natural features and rich plant/animal communities. They include 93 sites distributed throughout the state that are some of our finest examples of marshes, swamps, bogs, fens and other wetland communities.

But, wetlands also deliver services that communities value, even though we don't celebrate them very often. Those are sites the Wisconsin Wetlands Association chose as our other seven gems – the "workhorse wetlands" that often save the day when nature throws some of its toughest weather our way.

Storing runoff and reducing flood damage

Flooding brings health problems, safety concerns, economic loss and human tragedy. Wisconsin Emergency Management called the June 2008 flooding the most costly natural disaster in Wisconsin history that caused hundreds of millions of dollars in damages to homes and businesses. Saving wetlands is a critical part of the long-term solution to flooding. Often likened to sponges and dubbed "nature's hazard insurance," wetlands store rain that runs off land and is subsequently slowly released to the atmosphere, groundwater and adjacent lakes, rivers and streams. Due to their storage capacity and ability to slow the speed of flood waters, wetlands can help reduce the severity of floods and associated damage in downstream areas. This function is particularly important in urban and suburban areas where pavement enhances fast-flowing runoff.

But not all wetlands are equally effective in reducing downstream flooding during a given storm. It depends on the wetland's size, position within the watershed, topography, vegetation and how dry the wetland is before the rain starts falling. Nevertheless, across a whole watershed, protecting the full range of wetlands, including small isolated wetlands and floodplain wetlands, is an important strategy to slow down and lower flood waters. If flooding proves to be habitual, then removing or relocating homes and other structures from floodplains is an effective solution to contain flooding costs and damage. Restoring natural floodplain topography and wetland vegetation after buildings have been removed also reduces future flood damage downstream.

WETLAND WORKHORSE: Greenseams naturally prevents flood damage

The Greenseams Program identifies undeveloped land in and around the four counties and watersheds of the Greater Milwaukee area that can help naturally absorb rainwater and snow - melt to reduce flooding. Since 2001, nearly 29,000 acres have been identified as prospects for acquisition. As of spring 2009, Greenseams had protected 1,881 acres of these mature forests, stream corridors and wetlands by restoring natural water flow and absorption to retain runoff following rain events. The Greenseams Program estimates the protected acres can hold more than 830 million gallons of water! This innovative flood management project of the Milwaukee Metropolitan Sewerage District (MMSD) is reducing flood risks and damages for the 1.1 million residents and 28 communities of the Greater Milwaukee area.

Cleansing and filtering clean, healthy water

Wetlands are commonly compared to kidneys because of their ability to purify water. Acting as natural filters, wetlands remove pollution in runoff that flows from streets, parking lots, lawns, golf courses and agricultural lands. Wetland plants and microbes can trap sediments, remove nutrients like nitrogen and phosphorus, retain heavy metals, and break down animal wastes and a variety of toxic substances such as pesticides. This function is critical to maintaining clean and healthy waters that are drinkable, swimmable and fishable. While technological means to remove such pollutants from waters are expensive, healthy wetlands can provide this service for free, but the filtering capacity of wetlands is not unlimited. The plant varieties in wetlands that receive a heavy burden of pollutants change to favor the few species that can tolerate a heavy pollution load at the expense of sensitive and rare native species. Less diverse wetlands lose some of their filtering function and can degrade.

WETLAND WORKHORSE: Halfway Creek Marsh protects water quality

Halfway Creek Marsh, a tributary to the Upper Mississippi River north of La Crosse, drains a small watershed where farmland, a growing number of homes and commercial development have caused flooding and sedimentation problems in lower parts of the watershed. In 2005-2006, scientists at U.S. Geological Survey, University of Wisconsin-Madison, and U.S. Environmental Protection Agency studied sediments building up in the marsh. Using soil cores, historical maps, photos and other documents, the team reconstructed sedimentation patterns and rates from about 1860 to 2006. Results linked sedimentation to increased agriculture, large floods, upstream levee construction, channel alterations and sudden bursts from upstream dam failures. These historical deposits covered the marsh's 250-300 acres with a six-foot layer of clay, sand and silt. Remarkably, the marsh had retained 1.8 million cubic yards of material! In 1999-2000, the U.S. Fish & Wildlife Service and partners constructed a channel off Halfway Creek so the marsh could remain hard at work keeping large volumes of sediment pollution from reaching the Mississippi River. The project diverted the main burden of sediment and nutrients away from the more pristine wetlands at the lower end of the marsh. Sediment is periodically removed from this area to maintain capacity for future sediment storage and enhance the habitat value for wildlife, especially migrating waterfowl and shorebirds.

Preventing shoreline erosion

While some Wisconsin wetlands are considered isolated and landlocked, approximately three-quarters of wetlands in the state are situated along the shores of lakes, rivers and streams. Wetland plant communities that colonize shorelines adapt to natural fluctuations in water levels, flood surges and wave action while they protect shorelines against erosion. The roots of shoreline wetland vegetation serve as anchors, holding lakeshore and riverbank soil in place. Stems and leaves absorb and diffuse the punishing energy of waves along lakeshores and the flood currents that rise above the stream and riverbanks. This wetland function is especially important along shallow shores that flood frequently or receive significant wave action from wind and boat traffic.

Shoreline protection helps maintain waterfront property values and reduces the flow of eroded sediment that would otherwise wash into adjacent waters. In Wisconsin, lakeshore wetlands include both Great Lakes coastal waters and inland lakes. Large lakes typically have greater wave action and a greater need for a wider, deeper buffer of vegetation to stabilize the shore, so coastal wetlands along Lake Michigan and Lake Superior are especially important to protect the shoreline.

WETLAND WORKHORSE: Oconto Marsh protects shorelines

One of the largest wetlands along the western shoreline of Green Bay, Oconto Marsh surrounds the Oconto River mouth and stretches along the shore several miles north and south. This expansive wetland complex is made up of sedge meadow and marsh with islands of shrub carr. The vegetation varies with shoreland features such as low beach ridges and swales, abandoned oxbows, and meanders of the Oconto River forming a delta. Fluctuating water levels also influence the marsh vegetation and ability to sustain a stable shoreline. Erosion is a serious concern on parts of this coast that is regularly battered by strong waves and seiches – a tide-like rise and fall in water level caused by prolonged strong winds that push water toward one side of the lake. The dense network of thick rooted plants in Oconto Marsh holds the shoreline sediments in place. Cattails, bulrushes, and other emergent marsh plants absorb and diffuse the energy of the pounding waves and seiches. Sturdy wetland vegetation protects shorelines along much of the west shore of Green Bay and many other parts of Wisconsin's Great Lakes coastline.

Where groundwater is recharging and discharging

Underground aquifers store 97% of the world's unfrozen fresh water and in Wisconsin, drinking water for 70% of our residents. While some wetlands are perched atop a layer of rock or soil that isolates them from groundwater, many others are closely connected to groundwater. Some wetlands replenish groundwater as surface water permeates down through the soils. Many other wetlands are groundwater discharge areas, where groundwater flows to the surface as bubbling springs, for at least some portion of the year. Wetlands like fens depend on groundwater as their primary water source. In others, water flow changes directions seasonally depending on the height of the water table. Groundwater flow through riverine wetlands can keep stream flows stable during dry months and keep trout streams flowing with clear cold water. The filtering ability of wetland plants and soils helps protect water quality in lakes, rivers and streams.

WETLAND WORKHORSE: Pheasant Branch keeps the waters flowing

The Pheasant Branch Conservancy is a 550-acre natural area in Middleton, Dane County where a complex of wetlands flanks Pheasant Branch Creek. Each day, two large sets of springs release more than 2.6 million gallons of clear water into the Pheasant Branch wetlands that flow into marshy areas and the Madison lakes.

Areas upland of the conservancy are popular building sites, and studies have quantified the potential loss in spring flow that development can bring. Those studies are guiding the City of Middleton and the Friends of Pheasant Branch Conservancy in preserving the natural groundwater-wetland water flow in this system.

Providing a destination for recreation and education

Outdoor recreation is the most popular and fastest growing leisure activity in the United States, and Wisconsin is at the forefront of this trend. Residents and visitors enjoy hunting, fishing, paddling, hiking, birdwatching and wildlife viewing in wetlands. Wisconsin's marshes, swamps, bogs and fens are peaceful places to escape the fast pace of life and simply relax and enjoy the scenery. Wetlands in and near cities, particularly those with nature centers or in parks, provide fun learning areas for families, schools and communities.

WETLAND WORKHORSE: Exploring and enjoying the Mead

Every year, thousands visit the George W. Mead Wildlife Area at the convergence of Marathon, Portage and Wood counties in central Wisconsin. (See our June 2006 story Naturally green by design.) The site features more than 33,000 acres of wetlands, forests and grasslands. A mix of wetland habitats – sedge meadow, marsh, shrub carr, coniferous bog, and floodplain forest – is home to more than 267 species of birds, including ducks, geese, swans, herons, bitterns, gulls, terns, loons, grebes, plovers, sandpipers, rails, wrens and warblers. Turtles, including the state threatened Blanding's turtle, as well as frogs, dragonflies and mammals also inhabit Mead's wetlands.

Wildlife and humans alike flock here. The property offers more than 70 miles of trails providing easy access for hikers, bikers, birdwatchers and hunters. Open water areas are accessible for non-motorized boating and fishing. This site has become an excellent place for Wisconsinites to learn about wetlands and other natural habitats. Mead annually serves more than 4,600 students from 40 schools and 1,300 adults with no-charge educational programs. The Stanton W. Mead Education & Visitor Center – a stylistic, inviting, energy-efficient building – provides a perfect setting and resources for families, school groups and others. A variety of fun and educational public events are held at Mead each year, and a volunteer group, The Friends of the Mead/McMillan Association, offers programs for groups of all ages to increase understanding, appreciation, support and enjoyment of natural habitats and wildlife.

Supporting wildlife

Wetlands are incredibly efficient at capturing and using the sun's energy as well as recycling energy and nutrients. A strong food web base made up of plants, algae and microbes means that wetlands can support abundant wildlife. Many mammals, birds, reptiles, amphibians and insects rely on wetlands as feeding grounds, nesting habitats, spawning grounds, resting areas and travel corridors. Two-thirds of the 12 million waterfowl of the continental U.S. reproduce in the prairie pothole wetlands of the Midwest. In Wisconsin, three-quarters of wildlife species use wetlands during some stage of their life cycle, and more than a third of the state's threatened and endangered species depend on marshes, swamps, bogs, fens and other wetland habitats.

WETLAND WORKHORSE: Turtle Valley Wildlife Area

Spanning the headwaters of Sugar and Turtle creeks in northwest Walworth County, the Turtle Valley Wildlife Area comprises 2,300 acres of restored wetlands and prairies. At one time drained by an extensive network of tile and ditches, the area now features more than 1,800 acres of open wetland habitats, including shallow marshes, sedge meadows and low prairies. Ephemeral mud flats are exposed when water levels are low. Prairies with native grasses and flowers surround and buffer the wetlands from disturbance. Turtle Valley is home to more than 120 species of breeding and migratory birds that flock to the valley in tremendous numbers. The site provides especially good habitat for waterfowl and shorebirds like mallards, redheads, wood ducks, blue-winged teal, hooded mergansers, ruddy ducks, killdeer, American bitterns, lesser yellowlegs and several species of sandpipers. Numerous rare, threatened and endangered birds use these wetlands, including Forster's terns, Wilson's phalaropes, king rails, great egrets and whooping cranes. Rare reptiles like the state threatened Blanding's turtle are also found here. A wildlife area of this size and quality is especially valuable in the rapidly urbanizing southeastern portion of the state.

Supporting fisheries

Wisconsin's wetlands provide important nursery habitat for many species of fish, including game species like northern pike and walleye.

WETLAND WORKHORSE: Spoehr's Marsh

Lake Winnebago is one of the most popular fishing areas in the state with more than 75 fish species, including walleye, yellow perch, lake sturgeon and white bass. The walleye fishery is one of the most prized in the state. Yet most people don't realize that Lake Winnebago walleye depend on more than 10,000 acres of wetlands, including Spoehr's Marsh, along the Wolf and Fox rivers upstream. Unlike most strains of walleye that spawn on stream riffle and lake gravel bars, Lake Winnebago walleyes spawn in floodplain marshes and Spoehr's Marsh is the best studied of these spawning marshes. This 350-acre wetland 85 miles upstream of Lake Winnebago produces hundreds of millions of walleye fry each year.

Each year in April, spring rainfall and snowmelt cause the meandering Wolf River to rise over its banks. The river spreads into its wide floodplain, filling oxbows and marshes with floodwaters and transforming them into highly productive walleye nurseries. Lake Winnebago walleyes migrate nearly 100 miles upstream during spring flooding and lay their eggs on mats of winter-killed grasses, sedges and other vegetation in these floodplain marshes. On average, each female walleye in this system lays more than 113,000 eggs each spring. Mats of marsh vegetation protect the eggs by holding them above silty soils and associated fungi for 10-21 days until they hatch. Water continues to flow slowly in these floodplain marshes, which is critical for the nursery. Water flow attracts adult walleye into the marshes, keeps eggs clean, provides them with oxygen during development, and helps fry travel back into the river once they have hatched. Flooding typically lasts about four weeks each spring, after which time water recedes and marsh vegetation begins to grow again.

The Wetland Gems program recognizes particularly important wetland sites around the state, but does not overlook the value that all five million acres of wetlands bring to our landscapes and watersheds. All of Wisconsin's wetlands are workhorses that provide the benefits exemplified in these sites now and for generations to come.

Laura England and Katie Beilfuss work on outreach programs including Wetland Gems for the Wisconsin Wetlands Association.

For more on the Wetland Gems program, how sites were selected, ideas for citizen and community involvement, a visitor's guide, and a list and map of the 100 Wetland Gems sites, visit Wisconsin Wetlands Association, where you can also download and print one-page fact sheets about each of Wisconsin's 100 Wetland Gems. Funding for this project provided by The McKnight Foundation, the Wisconsin Coastal Management Program and the National Oceanic & Atmospheric Administration's Office of Ocean and Coastal Resource Management.