GROUNDWATER ON NATIONAL FORESTS AND GRASSLANDS: GEOSCIENTISTS CHANGING LAND MANAGEMENT

Forested lands, particularly those located in headwaters areas, have an outsized contribution to the US water supply, providing 46% of surface water supply in the continental US from about 29% of the land area (Liu, et al., 2022 – https://doi.org/10.2737/WO-GTR-100). The USDA Forest Service manages 193 million acres of national forests and grasslands in 42 states and Puerto Rico, much of it in headwaters areas. National forests and grasslands were established or acquired in part to sustain favorable conditions of water flow. Those lands include more than 220,000 miles of rivers and streams and 2.3 million acres of lakes, ponds and reservoirs.

Groundwater is a key component of the planetary water cycle, supplying baseflow to lakes, streams, springs, and wetlands, particularly in headwaters areas. In the early 2000s, the Forest Service recognized that it did not have a good understanding of the groundwater underlying its lands or the role that it played in sustaining the resources on the land. In response, the agency brought on additional geoscience expertise trained in hydrogeology and initiated efforts to assess and address groundwater resources in the context of its land management.

The new staff soon began to recognize the importance of groundwater in fostering and sustaining biodiversity on the national forests and grasslands. The relatively new concept of groundwater dependent ecosystems (GDEs) originating in Australia and other countries was embraced as a foundation for promoting increased awareness and support across the agency and with stakeholders and partners. The agency developed GDE inventory and monitoring protocols to provide a systematic approach for identification and characterization of the resource (https://www.fs.usda.gov/managing-land/natural-resources/geology/groundwater/publications). The agency also worked with partners, including The Nature Conservancy, to develop tools and datasets to support groundwater stewardship.

Today, awareness of the importance of groundwater resources on national forests and grasslands is prevalent across the agency. There is broad recognition of the important role GDEs play as refugia during climate extremes and at-risk species habitat. Groundwater resources are regularly included in the environmental evaluations required under the National Environmental Policy Act.