Specific Critical Lands Along the Flathead River
Braided River & Islands
The Flathead River Islands area is the highly braided area of the river, including islands, sloughs, wetlands, gravel and sandbars. It is located north of Flathead Lake, south of the Evergreen community, and east of Kalispell.
The wetlands and floodplains provide benefits such as capturing and storing nutrients and sediments which helps maintain high water quality.
The water flowing in the river controls the natural plant communities present on the islands. Young willow and black cottonwood communities are most common after gravel or sandbars are created by natural floods. In less frequently flooded areas, such as terraces, the forest becomes dominated by black cottonwood and red-osier dogwood. In areas where flooding is uncommon, conifers dominate.
Vegetation & Wildlife
The Flathead River Islands provide valuable fish and wildlife habitat. Bull trout and cutthroat trout use the river for migration. They winter in several locations around the islands where water flows are slower, there is protection from predators and water temperatures are higher.
The vegetation on the islands, river banks and in wetlands provide nesting and winter habitat for bald eagles. It also provides important year-round habitat for river otters, beavers, osprey, great blue herons, cormorants, wild turkeys and pheasants. The area has the highest density of beaver colonies in Montana and large populations of river otter and osprey.
The area is also very popular for hunting, fishing, bird watching and boating. The Department of Fish, Wildlife and Parks has a fishing access at the Owen Sowerwine Natural Area and Leisure Island on the west side of the river. The area was also a traditional river crossing area for the Kootenai Tribe.
Environmental Sensitivity & Development
The Flathead River Islands are unique and environmentally sensitive. The Stillwater and Whitefish Rivers contribute significant nutrient loads to Flathead Lake. These nutrients enter the Flathead River in this braided section. Nutrient filtering and sediment retention provided by wetlands and the floodplain in this area are critical for protecting water quality downstream, as well as protecting wildlife and plant species dependent on clean water.
Development pressures are high. Threats to the area include housing development (along with septic systems, pets, removal of vegetation, etc.) and timber harvesting. Degradation of this area can contribute to water quality deterioration in the river downstream and in Flathead Lake.
By maintaining or restoring native vegetation on the islands, floodplains and wetlands, we can help ensure that clean water, fish and wildlife, and the scenic beauty of the area can be enjoyed in the future.
The area known as Foys Bend includes several hundred acres of wetlands and riparian forests along the Flathead River, before the river turns east along Lower Valley Road. These beautiful lands along the river provide excellent recreation opportunities for boaters, fishermen and wildlife watchers, as well as outstanding wildlife habitat for a variety of wildlife species.
The riparian area is blanketed by a black cottonwood forest. Cottonwood trees are good indicators of healthy riparian areas and floodplains. There are few mature cottonwood forests left along the Flathead River. These forests provide valuable wildlife habitat for a variety of songbirds. In fact, wetland and riparian habitat provide breeding and nesting areas for 134 (55%) of breeding birds in Montana.
The wetlands at Foys Bend are known as backwater sloughs. These sloughs support large numbers of waterfowl during migration. The wetland and riparian vegetation in this stretch of the river also provides significant winter habitat for bull and westslope cutthroat trout. The wetlands and riparian areas help slow down water flows and keep water temperatures in the river moderate. In the winter, bull trout need areas like this to survive.
The wetlands also provide habitat for white-tailed deer, river otter, beaver, osprey and bald eagles. Osprey need good water clarity for fishing.
The wetlands and riparian forests are important for maintaining clean water in the river and lake. Trees and other plants capture and trap nutrients, sediments, chemical pesticides, and organic waste that run off city streets, lawns, construction sites and agricultural fields. By storing and filtering nutrients and pollutants, these areas reduce the amount of pollutants entering the river, lake and the groundwater. This is an important service provided by nature, because many people rely on the shallow groundwater aquifer for their drinking and household water.
Like many areas in the valley that are beautiful and close to water, development pressures are high. When possible, development should be located on upland areas, away from wetlands and riparian areas. As Kim Davis, a Kalispell resident, wrote in a January 14, 2003 letter to the editor of the Daily Inter Lake “I personally would hope that we can grow in a manageable way and still maintain the identity, characteristics, and values that have caused long term residents to stay and have attracted new residents.”
Whether it is by participating in land use planning or by practicing stewardship on our own property, we need a collective effort to protect and restore lands critical for clean water, including the wetland and riparian vegetation along rivers and streams. Protecting these areas will help ensure that clean water, fish and wildlife, and the scenic beauty of the area can be enjoyed now and in the future.
There are several sloughs, also known as oxbow wetlands, along the Flathead River as seen in the Landsat image above. Oxbow wetlands are crescent-shaped lakes lying along a winding river. The oxbow is created over time as erosion and deposits of soils change the river’s course, cutting off the oxbow from the river’s channel.
Egan, Church, Half Moon, Fennon, McWenneger and Weaver sloughs are naturally created oxbow wetlands associated with a previous course of the Flathead River. This complex of sloughs is located north of Flathead Lake along the Flathead River. Weaver Slough lies along the previous course of the river when it flowed into Flathead Lake at Somers. The river’s ability to form new sloughs has been reduced by Hungry Horse Dam and development, making these existing sloughs and associated wetlands irreplaceable.
The sloughs are used by a great number of migratory waterfowl, osprey, upland game birds, great blue heron and double-crested cormorants. Waterfowl move between the sloughs and Flathead Lake for food and nesting cover. The riparian and wetlands associated with the sloughs provide imporant habitat for river otter and other wildlife that travel along the river.
These sloughs also provide habitat for a number of threatened and endangered species, including bald eagles, bull trout and westslope cutthroat trout. Bull and westslope cutthroat trout were tracked using radiotelemetry by Montana Fish, Wildlife & Parks between 1999 and 2002 (Hungry Horse Mitigation Project). These fish were found to overwinter in the mainstem of the Flathead River, particularly near wetlands and sloughs along the Flathead River that have extensive vegetation cover, such as woody debris and overhanging riparian vegetation.
Farming is the predominant land use in the slough area. The area has some of the finest agricultural soils in Montana, comparable to the soils in the Midwestern “bread basket.”
Egan Slough Local Zoning District
Landowners around Egan Slough worked together to form a local zoning district to help protect agricultural land in the area. The Flathead County Commissioners approved the zoning district which includes limiting land subdivision to 80 acres to help maintain the area’s farming character.
The sloughs and associated wetlands are within the floodplain of the Flathead River and provide important floodplain functions for the river, including water storage, flood prevention and protecting water quality. Wetlands help take up and store nutrients in the wetland vegetation.
A Landowners’ Guide to Montana Wetlands provides additional information about wetlands and what you can do to protect them. You can get a hard copy by calling the Montana Watercourse at 406-994-6671.
Conservation Easement Protects Church Slough
Church Slough, a magnificent oxbow slough along the Flathead River north of Flathead Lake, is rich in wildlife and bird species. Landowners Ben and Maureen Louden decided to protect about 300 acres of wetlands, riparian habitat, floodplain and farmland at Church Slough with a conservation easement that helps them maintain their property in one piece to pass on to their children while protecting unique wildlife, water quality, and farmland values.
The Flathead Land Trust holds the conservation easement. A U.S. Fish & Wildlife Service North American Wetlands Act grant helped purchase the easement (development rights). Numerous partners working with the River to Lake Initiative helped make this project a reality, including Fish, Wildlife and Parks, the American Bird Conservancy, the Flathead Lakers, and others.
Conservation of Church Slough adds to a network of protected critical lands in the River to Lake Initiative focus area that help maintain clean water in the river and Flathead Lake.
McWenneger Slough, an oxbow lake formed by the Flathead River, is an outstanding complex of wetlands and riparian forests. McWenneger Slough is located east of Evergreen and the Flathead River. Views of the wetland can be seen to the north of Highway 35 and to the east of Columbia Falls Stage Road. The land surrounding McWenneger Slough has been in family farms for several generations. One of the major landowners speaks not only of the beauty of the area, but the unique wildlife and plants he has observed over the years.
McWenneger & Weaver Sloughs Conservation Project
You may have read in our previous newsletters about the Weaver and McWenneger Sloughs Project. This collaborative effort, led by the Flathead Land Trust, provides long-term protection for water quality as well as wildlife habitat, recreation and scenic beauty.
Success in securing fisheries mitigation funds from the Bonneville Power Administration allowed for the purchase of development rights in the form of a perpetual conservation easement on the Beutchel property. The Flathead Lakers thank the Beutchels for their dedication to protecting this critical area.
There are 300 acres of wetlands and riparian forests associated with McWenneger Slough. The wetland is particularly significant for wildlife. It is connected to the riparian corridor along the Flathead River, providing summer habitat for migratory waterfowl, common loons, trumpeter swans, neo-tropical migrants and resident birds such as pileated woodpeckers and kingfishers, as well as nesting sites for Canada geese.
One of the seven mature cottonwood forests along the Flathead River between Columbia Falls and Flathead Lake is found at McWenneger Slough. Cottonwood trees are important indicators of healthy riparian areas and floodplains. These areas help maintain clean water in rivers and lakes by filtering out sediments, providing soil stability, and slowing water flow, thus reducing potential flooding.
Many land owners recognize the significance of conserving the riparian corridor and associated wetlands along the Flathead River. Protecting a major portion of McWenneger Slough was a first, important achievement in the Critical Lands Project’s long-range strategy to protect priority riparian areas and wetlands that are important for keeping Flathead Lake and its tributaries clean and healthy.
Weaver Slough, a natural oxbow lake
Weaver Slough, located north of Somers, south of the Flathead River and southeast of Kalispell, is one of six naturally created oxbow lakes associated with the previous course of the Flathead River. This portion of the Flathead Valley, south of Kalispell, is an important fly-way for migratory birds and a breeding area for several species of concern, including bald eagle, osprey, tundra swan and brown creeper. Weaver Slough is an important site for Canada geese, mallards, pintail, ruddy ducks, shovelers, pileated woodpeckers and kingfishers. It supports abundant populations of beaver, muskrats, river otter, and mink, and provides year-round habitat for ring-necked pheasants, wild turkeys, Hungarian partridge, and white-tailed deer.
Weaver Slough includes 200 acres, with approximately 150 acres of wetland/riparian habitat and five miles of shoreline along the slough. The shoreline is in excellent condition and densely vegetated with emergent vegetation and native shrubs. The interior of the slough contains several pothole wetlands, and cottonwood and aspen forest stands. The riparian corridor along Ashley Creek, between Weaver Slough and the Flathead River, is in good condition and is used widely by a variety of wildlife species, including grizzly bears, mountain lions, migratory waterfowl and songbirds. Weaver Slough can be viewed as one ecological unit comprising the slough, some of the riparian corridor on Ashley Creek, and extending south towards the lake, partially including the Blasdel and Flathead Lake Waterfowl Production Areas.
A number of elongated wetlands lie between Weaver Slough and the lake; most show signs of degradation from agricultural practices. Water from the slough is regulated by two dikes and used for irrigation. Water removal does not appear to greatly affect water levels. Due to Kerr Dam operations, water levels in Weaver Slough rise about a foot in the spring and drop again in the fall. This fluctuation in water levels is not believed to have any negative impacts.
Weaver Slough’s wetlands provide a filtering function that helps protect water quality. Weaver Slough lies within the boundaries of the 100-year floodplain. The depth to the water table varies between 5 and 15 feet. Water exchange between the slough and the Flathead River occurs through Ashley Creek, which contributes high nutrient loads to the Flathead River. It is therefore critical that wetland and floodplain filtering functions be protected.
An intact strip of riparian and wetland vegetation around the slough provides important nesting habitat for birds and minimizes disturbances during critical migration periods. The area is privately owned and mostly farmed, except on the wetlands. There are presently four to five residences outside the slough. The open space provided by the farms still supports valuable wildlife habitat. Other nearby sloughs lack this degree of protection, and waterfowl production in those areas has declined.
There are few remaining sloughs in the area, and the rivers ability to form new sloughs has been reduced by dams and development. Floodplain regulations apply to this area, but they are considered to be inadequate for protecting groundwater resources. Incompatible urban development surrounding the slough and Ashley Creek could potentially lead to water quality degradation of the river and lake. The wetlands filter some of the excess nutrients before they reach the Flathead River. However, no data has been collected to determine the extent of the benefits this slough may provide for water quality protection.