These wetlands are formed in depressions in sandhill areas where groundwater intercepts the surface of the land. The most notable complex is the Sandhills, a 20,000 square mile area containing over 1 million wetland acres. The other complex is the Loup/Platte River Sandhills. Additionally, sandhill type wetlands are located in southwest Nebraska, in the Sandhills Borders area along the Elkhorn and Niobrara rivers, and in scattered pockets south of the Platte River.
The Sandhills region of north-central Nebraska comprises the largest contiguous tract of grassland remaining in the United States and the largest stabilized sand dune area in the Western Hemisphere. This region encompasses 19,300 square miles and overlies several extensive aquifers of the Ogallala Formation which contain a storage capacity of nearly one billion acre-feet of water. This vast water resource occurs both in the underground aquifer and above ground in the form of wetland areas. Sandhills wetlands are mostly freshwater and include saturated wet meadows, shallow marshes, and open-water lakes. It has been estimated that 177,000 acres of open water and marsh and 1,130,000 acres of wet meadows remain in the Sandhills (Rundquist 1983). An analysis of National Wetland Inventory digital data indicated that 369,606 acres of wetland were mapped in the Sandhills (LaGrange et al. 2004). The reason for the large discrepancy between the two surveys appears to be related to the techniques used. Rundquist (1983) used Landstat satellite generated imagery and mapped larger areas as wet meadow wetlands than did the National Wetland Inventory. The wetlands in the Sandhills range in size from less than one acre to 2,300 acres with greater than 80% of all wetlands estimated to be 10 acres or less in size (Wolfe 1984). Numerous wetlands are also associated with the streams and rivers within the Sandhills and along the Loup River and its tributaries after they flow out of the Sandhills. Several unique wetland types are located within the Sandhills. The Nebraska Natural Heritage Program has identified fens within the Sandhills (Steinauer 1995), a rare wetland type both in the Sandhills and throughout the United States. Fens are characterized by slightly acidic water and peat (undecomposed plant parts) soils that form in areas fed with a nearly constant supply of groundwater. Fens harbor several rare plant species such as cotton grass (Eriophorum polystachion), buckbean (Menyanthes trifoliata), and marsh marigold (Caltha palustris). The current range of these plants is mostly in colder regions north of Nebraska and the populations in the Sandhills are likely relics from a much cooler period in the Sandhills that have survived in these specialized habitats. In the western portion of the Sandhills there are numerous highly alkaline wetlands (Steinauer 1994) that harbor unusual plants and invertebrate life. These alkaline wetlands are very attractive to shorebirds because of the invertebrate life they produce.
Loss and Threats
Wetland loss in the Sandhills has occurred primarily through draining by surface ditches, beginning as early as 1900 (McMurtrey et al. 1972, U.S. Fish and Wildlife Service 1960). With the introduction of center-pivot irrigation systems to the Sandhills in the early 1970s, land leveling/shaping and local water-table declines have resulted in extensive wetland loss in some areas. While quantifiable data are not available for the Sandhills, estimates of wetland acres drained range from 15% (McMurtrey et al. 1972) to 46% (U.S. Fish and Wildlife Service 1986). Sandhills wetlands were given a priority 1 ranking (due to very extensive past losses) in the Nebraska Wetlands Priority Plan (Gersib 1991). Sandhills wetlands are most threatened by drainage to increase hay acreage. This drainage directly impacts the lake or marsh where the project occurs and also can lead to cumulative wetland loss both downstream and upstream as the channel becomes entrenched, lowering the water table and causing lateral drainages to occur that impact adjacent wetlands. Many smaller wetlands are also threatened by conversion from ranching to irrigated farming. Concentrated, large-scale irrigation development can result in long-term effects on wetland communities by lowering the groundwater table. Changing farm economics appear to have greatly slowed center-pivot irrigation development in the Sandhills, and the Conservation Reserve Program (CRP) allowed many pivots to be planted back to grass cover. However, this situation could change as CRP expires or economics change. Groundwater pollution, largely from agricultural chemicals and concentrated livestock waste, is a threat to the historically excellent water quality in the Sandhills. Nitrate levels in groundwater exceed safe limits (10 mg/1) in some locations due to fertilizer application (NRC 1993, Engberg 1984). A potentially disastrous future threat is the sale and removal of groundwater to areas away from the Sandhills. With its extensive groundwater resources (Bleed and Flowerday 1989), the Sandhills area is sometimes touted for major water sales. Such a loss of water would greatly impact the region’s lakes, marshes, and meadows since they are connected to the groundwater (Winter et al. 2001).
Functions and Values
Sandhills wetlands are extremely valuable to the region’s ranchers and the ranching economy. These wetlands, especially the wet meadows, provide abundant and nutritious forage that is used as winter cattle feed. Wetlands also offer grazing sites and a source of water to livestock. More than 300 species of birds have been recorded in the sandhills region. Of these, over 125 show an ecological affinity to wetland habitats including large numbers of waterfowl, shorebirds, and waterbirds. (Bleed et al. 1989). The North American Waterfowl Management Plan lists the Sandhills as a habitat area of major concern in North America (U.S. Fish and Wildlife Service and Canadian Wildlife Service 1986). The Sandhills are the most important waterfowl production area in Nebraska and are considered by Bellrose (1980) to be the best duck production area south of the Prairie Pothole Region. The Nebraska Game and Parks Commission counted an average of 218,414 ducks by aerial surveys in the Sandhills during the 1999-2002 nesting seasons (Vrtiska and Oldenburger 2002). These aerial counts are not corrected for visibility bias, which means the actual number of breeding ducks in the Sandhills could be 2-3 times the number actually counted. The most common species of nesting waterfowl include mallards, blue-winged teal, gadwalls, northern shovelers, northern pintails, redheads, and ruddy ducks. Production from the Sandhills Canada goose flock provides a fall flight that exceeds 10,000 birds (M. Vrtiska, pers. comm.). There are probably 50-60 pairs of nesting Trumpeter swans and they are expanding their nesting range throughout the Sandhills (M. Vrtiska, pers. comm.). Several state and federally listed threatened and endangered species use the Sandhills and associated wetlands. The migration corridor of the endangered whooping crane encompasses most of the Sandhills. Threatened bald eagles move through the area during migration and winter along Sandhills rivers, and several nests have been built by bald eagles along sandhill rivers and in wood lots adjacent to more permanent wetlands. Wet meadows provide habitat for the western prairie fringed orchid, which is a threatened species. Most of the lakes in the Sandhills are too shallow or alkaline to support game fish populations. However, some freshwater lakes, and their associated wetlands, have adequate water depth to over-winter fish and support an exceptional warm-water fishery. Although over 75 fish species (including many non-native species) occur within the Sandhills, the most common sport fishing species are northern pike, yellow perch, largemouth bass, bluegill, and crappie. Sandhills streams and their associated wetlands also provide habitat for 3 state threatened fish species in Nebraska: the northern redbelly dace, finescale dace, and blacknose shiner. Wetlands in the Sandhills function both as groundwater discharge and recharge sites, though recharge usually occurs only during heavy precipitation events in the spring (Bleed and Flowerday 1989). Although precipitation is low and evaporation rates are high, the large underground reservoir, known as the Ogallala Aquifer, provides a water table at or near the surface for discharge into a vast array of wetlands, even during drought. Agricultural, residential and municipal water supplies within the region, and a sizeable portion of the rest of Nebraska, are dependent upon the Ogallala Aquifer as their sole source of water. The Sandhills region in general represents one of Nebraska’s most popular tourist areas. Visitation data from Valentine and Crescent Lake National Wildlife Refuges as well as the presence of many State Wildlife Management and Recreation Areas within the Sandhills reflect well on the recreation values these wetlands provide. Camping, canoeing, boating, fishing, hunting, trapping, birdwatching, and wildlife photography are common recreational activities within this area.
Select Public Use Areas
http://mapserver.ngpc.state.ne.us/website/gpc_land/viewer.htm. http://mountain-prairie.fws.gov/refuges/ne/. C Cottonwood-Steverson Lake WMA, 28 mi. N. of Hyannis, Cherry Co. C Crescent Lake National Wildlife Refuge, 23 mi., N. of Oshkosh, Garden Co. C Ballard’s Marsh WMA, 18 mi. S. of Valentine, Cherry Co. C Valentine National Wildlife Refuge, 22 mi. S. of Valentine, Cherry Co. C American Game Marsh WMA, 19 mi. S. of Johnson, Brown Co. C South Pine WMA, 11 mi. S. of Long Pine, Brown Co. C Twin Lakes-Rock County WMA, 18 mi. S, 3 mi. E of Bassett, Rock Co. C Goose Lake WMA, 6 mi. S, 10 mi. E. of Chambers, Holt Co.
Conservation Programs and Contacts Sandhills Task Force- The Task Force is composed of ranchers, Nebraska Cattleman members, conservation organizations, and government agencies. The Task Force was formed to address issues of common concern relating to the ecology of the Sandhills, including wetlands, and sustaining the ranching community. Contact the Sandhills Coordinator, U.S. Fish and Wildlife Service, P.O. Box 1686, Kearney, NE 68848, (308) 236-5015. http://www.sandhillstaskforce.org/. Other contacts include the Nebraska Game and Parks Commission District Office in Bassett (402) 684-2921.
Loup/Platte River Sandhills Profile
The Loup/Platte River Sandhills wetland complex is in a narrow band of wind-deposited sand extending from the confluence of the Platte and Loup Rivers at Columbus, west to near the town of Ravenna. Wetlands are most numerous in a 70 square mile area south of Genoa. This complex was called the Platte-Nance-Merrick county Sandhills complex by Gersib (1991). Within these sandhills are numerous freshwater wetlands. These wetlands are mostly small (<5 acres) and range from temporarily to semipermanently-flooded. Some information suggests that the groundwater that recharges these wetlands is related to levels in the Platte and Loup rivers, but little quantitative information is available.
Loss and Threats
Some drainage and cropping of these wetlands has occurred, however, losses within this complex appear to be less than in many other complexes in the state. Threats to these wetlands are primarily related to the potential of local groundwater pumping drawing down water tables and causing the wetlands to lose their water source. This complex may also be impacted by alterations of flows in the Platte and Loup rivers, but this connection is currently not well understood. In the early 1970’s, there was a proposal to drain a large number of wetlands within this complex to facilitate conversion to agriculture (Farrar 1974), and this threat remains.
Functions and Values
Unfortunately, little is known about how this wetland complex functions. The wetlands are known to provide good habitat for nesting waterfowl and likely provide habitat for other water birds. Locally, the area provides recreation for waterfowl hunters. These wetlands provide water and forage production for area livestock. The role that these wetlands play in the water quality and groundwater dynamics of the region needs further investigation.
Select Public Use Areas
http://mapserver.ngpc.state.ne.us/website/gpc_land/viewer.htm. C Sunny Hollow WMA, 4 mi. S. and 1 mi. W. of Genoa, Merrick Co.
Conservation Programs and Contacts
Contact the Nebraska Game and Parks Commission District Office in Kearney (308) 865-5310 or Norfolk (308) 370-3374.