Watershed management

DEFINITION: Policies governing the use of land areas bounded by drainage divides within which precipitation drains to particular watercourses or bodies of water

Human activity can cause unanticipated changes in watersheds, affecting the hydrologic balance. Careful management of watersheds is important because land use alters the balance between storage and dispersal of precipitation, in many cases increasing erosion, stream sedimentation, and flooding hazards.

Watersheds are defined at many scales: The Mississippi River contains the Ohio River watershed, which in turn contains smaller watersheds. A fundamental part of the hydrologic cycle, the watershed collects and stores precipitation in soils, lakes, wetlands, or aquifers and disperses water by evaporation, plant transpiration, surface runoff, springs, and base flow to streams. Watersheds of different geographic regions have distinctive characteristics based on climate, topography, and soil type; therefore, the natural variability among watersheds is predictably large. In arid regions, precipitation occurs as intense, infrequent storms, with most of the water rapidly running off and eroding soil with little protective vegetation. Watersheds in humid areas are characterized by frequent, usually gentle rain that replenishes aquifers and sustains streams, springs, and wetlands.

Ecologically, the watershed provides and nutrients for plants and animals, including humans. Land use can disrupt a watershed’s by disturbing habitat and cycling through soil loss and removal of native vegetation. The role of the watershed in environmental problems such as flooding, erosion, sedimentation, and ecological disruption has led to increased emphasis on the watershed as the basic unit for environmental management, rather than political units such as states or counties.

The 1954 Watershed Protection and Flood Prevention Act authorized the secretary of the US Department of Agriculture (USDA) to manage watersheds in cooperation with states and local organizations, such as soil and water conservation districts. The driving idea behind the act is that floods are better controlled through management of upstream in the watershed than through downstream engineering projects. The act requires local interests to contribute up to 50 percent of the costs to ensure local support for watershed projects. In contrast, Army Corps of Engineers flood-control projects originally were funded entirely by the federal government. The Watershed Protection and Flood Prevention Act is generally administered through the USDA’s Natural Resources Conservation Service, formerly the Soil Conservation Service.

Recognizing the need for basin-wide planning, the federal government created the Water Resources Council through the 1965 Water Resources Planning Act. This council created planning commissions but fell into disfavor and lost funding because the river basins were too large for effective planning.

A major step in watershed management was taken with the 1972 Clean Water Act. With this act, land management began to include water-quality control. Non-point sources of were targeted, among them agriculture, forestry, mining, and disposal. Most states passed laws directing the use of certain widely accepted methods of preventing soil and water problems (known as best management practices, or BMPs) to protect or rehabilitate watershed functions. The Clean Water Act provided for regulation of land use, initially through incentives. The 1985 Food Security Act provided incentives for landowners to control on highly erodible croplands. The act’s “swamp buster” provisions directed protection of existing and also provided incentives for wetlands restoration. The 1986 amendments to the 1974 Safe Drinking Water Act encouraged public suppliers of drinking water to protect wellheads. The 1987 amendments to the Clean Water Act encouraged states to address non-point source pollution.

State regulations on non-point source pollution range from voluntary compliance with BMPs to strict enforcement of BMPs with fines for noncompliance. In general, however, such regulations have become increasingly detailed and comprehensive. The concept of the total maximum daily load (TMDL) permissible for non-point source pollutants has been introduced, but determining TMDL is costly and difficult because appropriate loads vary with land use and with watershed.

Over time, Americans’ perspectives on land and water management have broadened. Whereas management initially focused on single farms or individual fields, the watershed view has come to be widely accepted. This change has been influenced in part by concerns about the greenhouse effect, in which atmosphere-biosphere-hydrosphere-terrasphere interactions are critical. The term “ecosystem management” may better reflect watershed management focus in the future.

Watersheds are managed for a spectrum of land uses, including water supply, settlement, grazing, crop production, forestry, and recreation. Management focuses on water, sediment, and wastes. Water management generally seeks to reduce runoff; exceptions are landfills and mine spoils in which infiltration is minimized. Sediment management seeks to prevent soil erosion or to trap eroded sediment. Waste management seeks to distribute the waste load properly and to prevent it from reaching water. The appropriate strategies for achieving these management goals vary from problem to problem. For example, in forestry one strategy might include re-vegetating logged areas, diverting water from logging roads, and closing logging roads after use. The overall approach to watershed management is to identify the problem and its source and then select and implement BMPs. While the law requires that BMPs be considered, no definitive catalog of such practices exists. Many state agencies have written and assembled their own collections of BMPs for various land uses, which are available to the public. Public education and public participation in decision making have played increasingly important roles in sustainable watershed management in the United States.

Bibliography

Argaw, Temesgen, Medskerem Abi, and Esubalew Abate. "The Impact of Watershed Development and Management Practices on Rural Livelihoods: A Structural Equation Modeling Approach." Food, Service, and Technology, vol. 9, no. 1, 1 Aug. 2023, doi.org/10.1080/23311932.2023.2243107. Accessed 24 July 2024. Black, Peter E. Watershed Hydrology. 2d ed. Chelsea, Mich.: Ann Arbor Press, 1996.

France, Robert L., ed. Facilitating Watershed Management: Fostering Awareness and Stewardship. Lanham, Md.: Rowman & Littlefield, 2005.

Heathcote, Isobel W. Integrated Watershed Management: Principles and Practice. 2d ed. Hoboken, N.J.: John Wiley & Sons, 2009.

Newson, Malcolm. Land, Water, and Development: Sustainable and Adaptive Management of Rivers. 3d ed. New York: Routledge, 2009.

Satterlund, Donald R., and Paul W. Adams. Wildland Watershed Management. 2d ed. New York: John Wiley & Sons, 1992.