Inventory Monitoring, and Assessment
The Bureau of Land Management (BLM) quantifies and describes the public land resources to enhance our understanding of the entire landscape ecology. Water resources quality and quantity are important components of those landscapes.
Water resource issues on the public lands are addressed by the BLM’s Soil, Water, and Air program, which has the lead responsibility for developing and implementing the water quality, water rights, and surface water and groundwater policies of the BLM. BLM’s Soil, Water, and Air program also leads efforts to assess and restore water quality conditions and to manage water resources on public lands.
Some rain and snow falling to the ground is transformed by several hydrological processes into runoff, streamflow, and groundwater. The vast acreage of public lands generates substantial surface runoff and stores large volumes of groundwater. The land-use activities that BLM permits on this vast acreage have a direct effect on the quality and quantity of the water generated. Because water is in short supply throughout much of the West, where BLM is the major land management agency, waters derived from the public lands are a valuable natural resource.
Groundwater sources are integral in maintaining healthy plant communities and wildlife habitats, and provide drinking water for wildlife and people. Recharge, withdrawal, and infiltration of contaminants affect groundwater resources.
Surface water (e.g., lakes, rivers and streams) provides important habitat for native fishes and other aquatic organisms. The water present at a site must be of sufficient quantity and quality to sustain these uses, and BLM management decisions influence both water quantity and quality. Amounts of rain and runoff, water impoundments and withdrawals, pollution from outfalls, erosion of soils, and the health of the watersheds and riparian areas affect surface water resources.
Interaction of Surface and Groundwater
Nearly all surface-water features (streams, lakes, reservoirs, wetlands, and estuaries) interact with groundwater. Surface water bodies can gain water and solutes from groundwater systems and conversely surface water can be a source of groundwater recharge and can cause changes in groundwater quality. Consequently, withdrawal of water from streams can deplete groundwater and likewise, groundwater drawdown can deplete water in streams, lakes, or wetlands. Pollution of surface water can cause degradation of groundwater quality just as pollution of groundwater can degrade surface water. Thus, effective land and water management requires a clear understanding of the linkages between groundwater and surface water as it applies to any given hydrologic setting.