I am not a native Nebraskan. Growing up in our neighbor to the east, I had only a vague idea of what the Sandhills were and had never set foot in them. That changed in 1982 when my wife and I took a month-long honeymoon trip through the western U.S. and Canada. We departed Iowa headed west on Highway 20 and before long were passing through some of the most amazing country I had ever seen. Miles and miles of grass-covered dunes interspersed with innumerable wetlands and lakes. This unique landscape rivaled the Rockies and the Pacific coast that we would later pass through, and the Sandhills of Nebraska began working their way into my heart and soul.
Eleven years later, I was hired as the wetland program manager for the Nebraska Game and Parks Commission, and I set out to explore my new home state. One of my first trips was to head back to the Sandhills. I was soon in an airboat speeding across the Marsh Lakes at Valentine National Wildlife Refuge. I visited with other biologists and ranchers to learn more and eagerly read An Atlas of the Sand Hills.
To the casual observer, the Sandhills may appear to be a dry landscape, and there certainly are large expanses of upland prairie. However, in many places, especially in interdunal valleys, there are also numerous lakes and wetlands. The vast groundwater underneath the hills reaches near the land surface, and lakes and wetlands arise. Wetlands are defined as having soils and a plant community that developed under periodically wet conditions, with the water either ponded on the surface or contained as groundwater near the surface. Some wetlands are associated with lakes, rivers, and streams, but many are isolated from other water bodies and immersed in the prairie landscape. Wetlands are dynamic and respond to changes in groundwater level, so their water levels can fluctuate dramatically over time.
The Sandhills is, by far, the region of Nebraska with the most wetlands. It is challenging to estimate their real extent, but the number of acres ranges from 369,606 to over 1.3 million. Individual wetlands range in size from less than an acre to over 2,300 acres, with greater than 80 percent estimated to be 10 acres or less.
Wetlands across the Sandhills are surprisingly diverse, and the main types include marshes, wet meadows, fens, lake and stream fringes, and alkaline wetlands. Many of these types intermingle across the landscape, so they can be a challenge to define. Marshes tend to have surface water from a few inches up to six feet deep. They are generally dominated by robust emergent plants, including cattails, bulrushes, sedges, rushes, arrowheads, even wild rice in some places, and in the deeper zones, floating-leaf and submergent plants occur. Wet meadows usually do not have standing water, but groundwater is within twelve inches of the surface. Meadows are mostly dominated by grasses, sedges, and rushes but also have a variety of wildflowers. The edges of nearly all Sandhills lakes, rivers, and streams have a wetland fringe, and the floodplains of rivers and streams can contain meander cutoffs (oxbows), which are a type of marsh. Fringe wetlands can be very narrow or wide depending on the lay of the land, are marsh-like in the deeper portions, and can grade into wet meadows if the landscape is relatively flat. Alkaline wetlands are mostly located in the western Sandhills, with the largest concentrations in Garden and Sheridan Counties. They generally do not have surface water outflow and receive much of their water input through groundwater discharge. Their alkalinity can become very high due to minerals that are concentrated through evaporation. This high alkalinity makes these wetlands home to a variety of unique plants and animals.
Wetlands of the Sandhills provide diverse benefits to people, especially considering that they cover only about 10 percent of the region. Not many people associate wetlands with clean water, though wetlands act as a filter, slowing water down and allowing sediment and many pollutants to settle out. As water slowly moves through the wetland, a series of chemical transformations take place that bind or alter some pollutants. The net result is that, generally, water leaving a wetland is of higher quality than water entering. This is important because the origin of much of the drinking water for many communities in Nebraska, including Omaha and Lincoln, ultimately is the Sandhills. Although the hydrology of Sandhills wetlands can be complicated, some wetlands help to recharge groundwater. Surface water held by wetlands can also reduce the impacts of flooding, because water would move downstream more rapidly if the wetlands were drained.
Wetlands are among the most productive biological systems known. They produce more plant and animal life per acre than cropland, prairies, or forests. Wetlands provide migration, breeding, nesting, and feeding habitat for millions of waterfowl, shorebirds, songbirds, and other wildlife. They are home to thousands of different plant and animal species, including many that are threatened or endangered. The Nebraska Natural Legacy Project (State Wildlife Action Plan) identifies all or parts of eight biologically unique landscapes (BULs) within the Sandhills, and all contain wetlands. Within these BULs are seven tier-1 at-risk plant species and thirty tier-1 at-risk animal species. The Sandhills are the most important waterfowl production area in Nebraska and one of the best duck production areas outside of the Prairie Potholes region just to the north. The abundant fish and wildlife of wetlands support many recreational uses, including wildlife observation, boating, hunting, and fishing. The amazing productivity of wetlands is not lost on ranchers, who rely on the land to make a living. Wetlands provide water for livestock, and the lush vegetation in and adjacent to wetlands provides important livestock forage, with wet meadows being especially valuable for hay production.
Thanks to the good stewardship of ranchers, the Sandhills remains an intact landscape. However, these wetlands are not entirely unaltered. Fragmentation has impacted wetlands via conversion of areas to row crops and development of some types of infrastructure. Plant and animal communities, including in Sandhill wetlands, evolved with natural disturbances, such as fire and grazing by native ungulates. These natural disturbances have been eliminated in many parts of the Sandhills, which affects the wetlands. Some wetlands were drained, or partially drained, by the installation of drainage ditches to improve hay production. Some streams were straightened to move water more quickly. The combined effects of ditches and straightening have caused some Sandhill streams to cut deeper (degrade), which lowers the water table and dries out adjacent wetlands.
A number of non-native invasive species are impacting wetlands, including the introduced variety of common reed (Phragmites), reed canary grass, redtop, garrison creeping foxtail, hybrid cattail, purple loosestrife, Eurasian water milfoil, and common carp. These invasives can crowd out native species and alter their habitat. But by far the greatest potential threat to Sandhills wetlands would be a decline in groundwater levels below normal cyclic variation. Wetlands are only present because groundwater reaches the surface, and their persistence depends on groundwater within at least twelve inches of the surface in most years. If groundwater levels were to drop even slightly, due to either human withdrawals or climate change, the wetlands would disappear, along with the benefits they provide.
Despite the losses and threats, there are still plenty of reasons for hope. When I came to Nebraska, I had the honor of joining the board of the Sandhills Task Force. Ever since, I have been inspired by the ability of ranchers and conservation agencies and organizations to work in partnership to implement projects that benefit wetlands, grasslands, wildlife, and people. I believe that if we continue to work together, the wonder of Sandhills wetlands can be sustained for future generations, including for my grandchildren. My hope is that long into the future, someone will still be able to head west from Iowa and fall in love with the land that we call the Sandhills.