Chapter 19: The Rainwater Basin of Nebraska
Physical Description: The Rainwater Basin area of Nebraska occupies about 4,200 square miles in 17 counties in the south central portion of the State. (See Figure XIX-1.) Within that area are scattered wetland basins formed when clay particles created a layer in the subsoil impervious to water movement. The impervious layer resulted in a perched water table. The sink-like basins receive water from rainfall, and vary in size and depth, producing a dynamic wetland complex. Temporarily, seasonally, and semi-permanently flooded wetlands occur in the Rainwater Basin. Each of these wetland types has distinctive soils, hydrology, and vegetation. Agricultural land use dominates the area, with grain (corn, wheat, milo, and sorghum), soybeans, and alfalfa being the main crops produced.
Characteristics and Functions: The Rainwater Basin wetlands
- Provide spring, migratory habitat for 5 to 7 million ducks and geese, including about 1 million snow geese, 90 percent of the mid-continental greater white-fronted goose population, 50 percent of the mid-continental mallard breeding population, and 30 percent of the continental northern pintail breeding population;
- Furnish breeding and nesting habitat for shorebirds, waterfowl, and other water-associated species;
- Support 2 federally-listed endangered species (bald eagle and whooping crane); and
- Contain about 15,400 acres protected by State or Federal ownership or contract programs. This acreage represents 45 percent of the area's remaining wetlands.
Original Acreage: Historically, nearly 4,000 individual wetlands occupied about 95,000 acres in the Rainwater Basin.
Current Acreage: Approximately 34,000 wetland acres remain in the Rainwater Basin.1 Virtually all of the remaining wetlands have been modified to some extent.
Trends: Trends vary by wetland type. Between the 1960s and the 1980s, shallower, more easily drained wetlands declined by 74 percent, deep wetlands declined by about 47 percent, and the intermediate depth wetlands declined by 20 percent, significantly changing the composition of wetlands in the Basin. A majority of the seasonally and temporarily flooded wetlands -- those more easily drained -- are privately owned. Thus, although Swampbuster and recent shifts in public policy have slowed conversion, the remaining wetlands continue to be vulnerable to conversion should economic conditions in the agricultural sector warrant. Further, even if conversion is not profitable, run-off from farms and roadways threatens the wetlands with siltation and chemical contamination.
Most wetland loss in the Basin has been to agriculture, although some loss has occurred as sections of roads and ditches were constructed and improved. Today drainage of wetlands to make the land more suitable for crop production is the major factor accounting for loss in the Rainwater Basin. While some of the smaller and shallower wetlands in the area may be effectively drained through leveling and grading, drainage of Rainwater Basin wetlands usually requires the excavation of large pits to store the drained water. The excavated material provides fill for the drained wetland.
Landowners drain wetlands by excavating pits in the floor of a wetland basin so that water that once spread shallowly, for days, weeks, or months at a time, over a relatively large, low-lying area is contained in a pit up to 20 feet deep. To drain one wetland acre can require a pit from 1000 to 2000 cubic yards in size, depending on whether the wetland is temporarily, seasonally, or semi-permanently flooded. Although rarely possible, pits are sometimes used in combination with drainage ditches. Whatever the method, complete drainage is seldom achieved. Partial flooding and some crop loss occurs on converted lands in at least one out of every five to seven years.
During the last 10-15 years, corn or soybeans produced on irrigated land has been the most profitable crop in the region; this status is expected to continue. During a dry year, grain sorghum or wheat are usually grown on non-irrigated wetland areas or on areas that are only partial drained.
Nebraska State law requires that persons using groundwater for crop irrigation purposes must prevent or control the irrigation runoff water. Consequently, irrigation water reuse pits, constructed to trap irrigation wastewater, are often placed in natural drainages. As a result, wetland effects are frequent. Reuse pits within closed watersheds trap natural run-off, reducing water permanence in the wetlands, causing shifts in plant species composition and abundance, and changing semi-permanently flooded wetlands to seasonally or temporarily flooded wetlands. Sometimes a reuse pit is located directly in a wetland basin, with excavated material used to fill part of the wetland. However, this practice has become rare in the last five years.
The profitability of a converted wetland is significantly affected by soil type and conversion costs. Drainage tends to be profitable in temporarily flooded areas with more productive soils and pit excavation limited to several hundred cubic yards. Drainage tends to be unprofitable in semi-permanently flooded areas with less productive wet soils and excavation exceeding 2000 cubic yards. For seasonally flooded wetlands, if soil is fairly productive and only moderate excavation is required, conversion can be profitable.2 Excavation costs have been rising at a rate of about 9 percent per year (faster than cash receipts), and thus conversion is becoming a less attractive proposition.
Most Rainwater Basin wetlands, including those in public ownership, are being degraded by siltation from adjacent farms and roads and contaminated by agricultural chemicals. Siltation gradually fills in the wetlands, altering aquatic, vegetative communities and reducing water retention by the wetlands. The wetlands are exposed to herbicides that can disrupt the composition of the plant community and reduce species diversity. Also, the wetlands are contaminated by insecticides that can alter the species composition and decrease the numbers of aquatic and terrestrial, invertebrate species.
The loss of Rainwater Basin wetlands has forced water-associated birds to concentrate in fewer wetlands. This condition increases the incidence of disease and death. Since 1975, approximately 200,000 birds have died of avian cholera in the Rainwater Basin, due at least in part to overcrowding. Avian cholera affects not only waterfowl, but crows, raptors, sandhill cranes, and other bird species. Overcrowding and disease in the Rainwater Basin is particularly troubling, because the area serves as migratory habitat for the endangered whooping crane.
Federal Programs and Projects
Much of the conversion in the Basin has been conducted with Federal assistance through cost-sharing programs for water management. In addition, agricultural subsidies (largely in the form of price and income supports) have encouraged landowners to drain wetlands. These programs offered incentives and funding for converting wetlands in an economic environment where private conversion was often unprofitable or, at best, only marginally profitable. Swampbuster eliminated the conversion incentive due to price and income supports. Although Swampbuster also made Federal cost-sharing assistance unavailable for projects which convert wetlands to agriculture, there are some exceptions in the law. These exceptions are particularly relevant to the Rainwater Basin, and Federal cost sharing for water management in this region continues to affect wetlands.
Two Federal cost-sharing programs assist in a wide range of soil and water conservation practices, and can lead to wetland drainage: the Agricultural Conservation Program (ACP) administered by the Agricultural Stabilization and Conservation Service (ASCS) and the Great Plains Conservation Program (GPCP) administered by the Soil Conservation Service (SCS). In recent years the ACP has spent $4-5 million annually in the area. The program covers 60 to 75 percent of the costs (up to $3500) of selected conservation measures, such as land leveling and the construction of irrigation water recovery systems. GPCP expenditures have averaged $1-1.5 million annually in the area, decreasing a bit in recent years. This program covers up to 60 percent of land leveling costs and up to 75 percent of the costs of irrigation water reuse systems.
Construction of irrigation water reuse pits has the greatest impact on wetlands. Captured water is reused for irrigation, which can remove or reduce the supply of irrigation water or natural runoff that would normally be available to adjacent wetlands. Recovery pits can also be enlarged three to four times for drainwater storage.
Assistance for "irrigation water conservation" is available for gravity-flow but not center pivot systems. The program is not supposed to bring new land under irrigation, so assistance is only available for projects on land which has been irrigated 4 out of the last 5 years. Despite this programmatic constraint and despite additional constraints introduced with Swampbuster, there are exceptions which allow continued subsidization of activities which affect wetlands. Some exceptions are provided for in the statutes and some stem from enterprising interpretations of the statutes and regulations. No one exception leads to a significant loss of wetlands, but collectively the exceptions degrade and diminish the stock. For example:
- If a wetland adjacent to an irrigated field is the most logical and feasible site for a recovery pit, the pit may be located in the wetland and still qualify for cost-sharing assistance. Since wetlands are almost always low-lying areas into which water drains, it is always going to be cheaper to locate recovery pits there than elsewhere.
- Because of what are considered "overriding technical factors" (usually cost considerations), price supports and deficiency payments for crops may be extended even in cases where some additional wetland is brought under cultivation. In most such cases, however, mitigation would be required by SCS and the design would have to be approved by the FWS.
- The ACP and GPCP programs require that recovery pits be designed with only enough capacity to capture irrigation flows. The programmatic requirements exclude capacity for rainfall runoff. However, SCS personnel indicate that cost sharing is not automatically denied for oversized pits. Rather, assistance is simply limited to that portion of the work necessary to construct a pit of the required capacity. Partitioning projects in this contrived way circumvents the intent of the conservation provisions of the statutes.
The commodity programs are designed to limit the production of certain crops while stabilizing or increasing farm income through crop price supports and direct payments to farmers. The basic tools have been nonrecourse commodity loans to support prices; deficiency payments to support income; and acreage set-aside, reduction, or diversion programs to restrict production.
Here as elsewhere, these subsidies have distorted market signals and induced the conversion of more wetlands to agriculture than was economically efficient. With the advent of Swampbuster, however, these incentives were eliminated. Swampbuster denies farm program benefits to persons who either convert wetlands after the date of enactment of the 1990 FACTA or plant on wetlands converted after December 23, 1985. Given the high rate of farm program participation in the Rainwater Basin, Swampbuster should pose a significant constraint on wetland conversion for agriculture.3
Although Swampbuster eliminated the incentive to convert wetlands in order to gain access to farm program benefits, there is a residual impact from the commodity programs. The crop subsidies in conjunction with low interest loans from FmHA keep more land in agriculture (especially marginal land) than would otherwise be the case. In the absence of the subsidies some of this land might revert to wetlands. Further, while the land remains in the agriculture sector, the runoff continues to degrade existing wetlands.
The Rainwater Basin's wetlands remain vulnerable to siltation and contamination from agricultural chemicals from adjacent cropland and rangeland. Irrigation wastewater containing herbicides from chemicals applied directly in irrigation water potentially poses an additional threat to the aquatic environment by concentrating herbicides and altering vegetal communities in the adjacent basins.4 Although the incentives have been much reduced, privately owned wetlands are still subject to draining and filling.
The high level of farm program participation in Nebraska in recent years suggests that if fully enforced, Swampbuster should continue to discourage wetland conversions in the Basin. However, if support levels continue to decline and the programs become more restrictive, the participation rate is likely to wane, and Swampbuster's effectiveness diminish.
Cost sharing for water conservation practices such as building irrigation water recovery pits is expected to continue causing wetland losses. Landowners sometimes build these pits with excess capacity to store rainwater runoff, depriving wetlands of moisture and adding to water available for irrigation. Although apparently prohibited, Federal funds continue to contribute to pit expansion projects which affect wetlands, because the projects are formally subdivided into segments that qualify for aid (and hence, ostensibly do not affect wetlands) and segments that must be privately funded.
- Water Management Projects:
Consider precluding the use of Federal ASCS and SCS financial and technical assistance on any soil and water conservation project that indirectly results in the destruction or functional degradation of wetlands.
The ASCS and the SCS have policies and procedures which no longer permit cost sharing for practices that drain or negatively affect wetlands. However, the ASCS's Agricultural Conservation Program and the SCS's Great Plains Conservation Program may still provide cost sharing and technical assistance for soil and water conservation measures, such as land leveling, terracing, and irrigation water recovery systems, that can indirectly contribute to wetland losses or degradation. Although these types of practices may not occur directly within a wetland, they can affect the hydrology of the area, resulting in the destruction or functional degradation of the wetland. Such financial and technical assistance encourages landowners to undertake inefficient and environmentally damaging projects. This type of assistance is inconsistent with other Federal activities to protect wetlands, such as the Swampbuster provision of the Food Security Act and Executive Order 11990 which directs Federal agencies to avoid adverse impacts to wetlands. Finally, Federal assistance for developing irrigation water resources promotes further agricultural productivity of surplus commodity crops.
Swanson, Larry D. 1986. The Profitability of Wetland Drainage in the Rainwater Basin of Nebraska. Prepared for the U.S. Environmental Protection Agency, Region VII, Kansas City, Kansas, 102 pp.
Gersib, Richard A., B. Elder, K.F. Dinan, and T.H. Hupf. 1989. Waterfowl Values By Wetland Type Within Rainwater Basin Wetlands With Special Emphasis on Activity Time Budget and Census Data. Nebraska Game and Parks Commission, Lincoln, Nebraska, and U.S. Fish and Wildlife Service, Grand Island, Nebraska, 105 pp.
Raines, Richard R., M.C. Gilbert, R.A. Gersib, W.S. Rosier, and K.F. Dinan. 1990. Regulatory Planning for Nebraska's Rainwater Basin Wetlands (Advanced Identification of Disposal Areas). Prepared for the Rainwater Basin Advanced Identification Study. U.S. Environmental Protection Agency, Kansas City, Kansas, and U.S. Army Corps of Engineers, Omaha, Nebraska, 46 pp.
1 This is the acreage for palustrine or depressional wetlands, which are the focus of this chapter. There are an additional 17,000 acres of riverine and lacustrine wetlands in the Basin.
2 Soil productivity at least 80 percent of that for upland soils and excavation less than 1000 cubic yards.
3 Feed grain and wheat program participation has grown from 70 percent to over 80 percent in Nebraska in recent years.
4 Although Nebraska law requires that wastewater from irrigation be kept on the operator's land, this law is rarely enforced.
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