Benefits of Forest Lands for Surface Water in Wisconsin
Quantifying the Role of Federal, State, and Private Forest Lands in Providing Surface Drinking Water Supply for Wisconsin
Introduction
Forests provide the most stable and highest quality water supplies among all land uses. Forests cover around 49.1 percent of the land in Wisconsin. All of the forests in Wisconsin are owned and managed by either federal, state, local, or private entities, thus it is critical to understand the role of these forest lands in providing water across the state and region. The result is derived from the project entitled "Quantifying the Role of Federal, State, and Private Forest Lands in Providing Surface Drinking Water Supply for the Upper Mississippi River".
Forest Lands by Ownership Type in Wisconsin
State and private forest (SPF) cover 75 percent of forested lands in Wisconsin. Of that amount, the majority of SPF lands was in family-owned forests accounting for 57 percent of forested land coverage. State and local-owned forests accounted for 21 percent of forested land coverage.
Figure 1. Forest Land Area by Ownership Group (USDA Forest Service, 2020).
Annual Water Supply
The water supply was calculated by accumulating the water volume generated from each land cover type in the entire river system upstream of a location of interest along the river network. The unit of water supply is million cubic meters per year.
About 39.2 percent of all Wisconsin surface water originated on SPF lands. The majority from the SPF lands was family-owned forests, which accounted for 56.4 percent of the surface water from the SPF. State and local-owned forest accounted for 25.2 percent.
Figure 2. Surface Water by Forest Ownership Type.
Average Annual Water Yield Between 2001 and 2010
Water yield is the amount of excess water leaving a watershed as streamflow after accounting for losses that include changes in water storage in the soil, evaporation, and transpiration from vegetation. In this study, water yield is the depth to which a watershed (HUC12) would be covered if all of the streamflow were uniformly distributed over it. The unit of water supply is million cubic meters per year.
Population Served by State and Private Forest Lands in Wisconsin
Wisconsin had a total of 44 surface drinking water intakes where at least some available water comes from SPF. About 40 percent of the total population of Wisconsin was served by surface drinking water overall.
About 203,000 people in Wisconsin were recieving more than 30 percent of their surface drinking water from SPF within the state.
Figure 3. Cumulative Frequency of Population served according to the Percentage of Water coming from Wisconsin SPF Lands.
Population Outside of Wisconsin Served by Water Originating from Wisconsin State and Private Forest Lands
State and private forest lands in Wisconsin supplied water to 119 surface drinking water intakes in other states (Missouri, Louisiana, Indiana, and Illinois).
Figure 4. Cumulative Frequency of Non-Wisconsin Population served according to the Percentage of Water coming from Wisconsin SPF Lands.
Authors
Ning Liu , Postdoctoral Research Fellow, U.S. Department of Agriculture Forest Service, Southern Research Station, Coweeta Hydrologic Lab, and University of Minnesota, College of Natural Resources, Department of Forest Resources, 301H Green Hall, St. Paul, MN 55108.
G. Rebecca Dobbs , Geospatial Research Associate, U.S. Department of Agriculture Forest Service, Southern Research Station, Coweeta Hydrologic Lab, Otto, NC 28763, and North Carolina State University, College of Natural Resources, Department of Forestry and Environmental Resources, Center for Geospatial Analytics, Raleigh, NC 27695.
Peter V. Caldwell , Research Hydrologist, U.S. Department of Agriculture Forest Service, Southern Research Station, Coweeta Hydrologic Lab, Otto, NC 28763.
Chelcy Ford Miniat , Research Ecologist, U.S. Department of Agriculture Forest Service, Southern Research Station, Coweeta Hydrologic Lab, Otto, NC 28763.
Paul V. Bolstad , Professor, University of Minnesota, College of Natural Resources, Department of Forest Resources, St. Paul, MN 55108.
Stacy Nelson , Professor, North Carolina State University, College of Natural Resources, Department of Forestry and Environmental Resources, Center for Geospatial Analytics, Raleigh, NC 27695.
Ge Sun , Research Hydrologist, U.S. Department of Agriculture Forest Service, Southern Research Station, Eastern Forest Environmental Threat Assessment Center, Forestry Sciences Laboratory, Research Triangle Park, NC 27709.
Mattie Gisselbeck , Research Assistant, University of Minnesota, College of Natural Resources, Department of Forest Resources, St. Paul, MN 55108.
References
Sass, E. M., Butler, B. J., & Markowski-Lindsay, M. A. (2020). Forest Ownership in the conterminous United States circa 2017: Distribution of Eight Ownership Types - Geospatial Dataset. Forest Service Research Data Archive. https://doi.org/10.2737/RDS-2020-0044
USDA Forest Service. (2021). Family Forest (10+ acres) Ownership Characteristics: Wisconsin, 2018 (NRS-RN-308; p. NRS-RN-308). U.S. Department of Agriculture, Forest Service, Northern Research Station. https://doi.org/10.2737/NRS-RN-308
