Watershed Management Planners Recommend an Achievable Goal of 10% Increased Infiltration
Will Retain Long-term Goal of 25% Recovery of Lost Infiltration as Discussion Guide Only
From the time of European settlement of the Lake Wingra watershed around the 1830’s the quantity of rainfall and snow melt that soaks into (infiltrated) the ground, entered the groundwater and flowed into Lake Wingra has been reduced by an estimated 99,234, 028 cubic feet (cf) according to figures provided by the Wisconsin Geological and Natural History Survey. The Wingra Watershed Planning Steering Team recommended adopting a short-term goal to capture about 10% of that “lost infiltration”, according to meeting of the October 17, 2013 meeting at which the recommendation was made. A longer-term goal of recapturing 25% of lost infiltration will continue to be a discussion point to guide future planning.
Groundwater is an important natural resource in the Lake Wingra Watershed. Groundwater supplies the springs, wetlands, and the lake itself and adds immeasurably to the quality of like in Madison.
Groundwater is “the water that occurs below the Earth’s surface that is contained in pore spaces within the bedrock,” Allaby, Oxford Dictionary of Ecology, 1998. Hydrology is the study of the hydrologic cycle, in other words, the flow of water through the air and land.
Two recent publications add to our understanding of the groundwater hydrology of Dane County and the Lake Wingra Watershed.
On the local watershed scale, “Groundwater Status Report Prepared for Friends of Lake Wingra (groundwater status report) (Kniffin, 2011) is an excellent place to start to understand the water issues in the Wingra Watershed.
“This Groundwater Status Report is a summary of existing research, personal interviews and policies with respect to spring and groundwater flow beneath the Lake Wingra watershed. The report begins by briefly describing the springs in the Lake Wingra watershed and how storm sewer runoff has affected their flow rates. The report summarizes the hydrology, groundwater storage and groundwater recharge of the Lake Wingra Watershed and the aquifers beneath it. Looking at all aspects of human interactions with water resources, the report then discusses water consumption and disposal, shallow and deep aquifer connections and a few key groundwater policies established in the State of Wisconsin and City of Madison. At the end of select sections, there are “Topics Recommended for Further Exploration”, which are intended to help identify future areas of opportunity for the Friends of Lake Wingra and other readers.”
At the Dane County level, a new Bulletin (Groundwater Recharge in Dane County, Wisconsin: Estimating Recharge Using a GIS-based, Water-balance Model, by Hart, Schoephoester, and Bradbury) is available from the Wisconsin Geologic and Natural History Survey.
From the Bulletin’s abstract:
“Recharge is water that moves from the ground surface down into the groundwater. It’s also the ultimate source of all groundwater. Hydrogeologists at the Survey developed a groundwater management tool to help guide land-use decisions in Dane County.
The recharge estimates described in this report represent an improvement over previous estimates. This publication describes the inputs used to calculate recharge and includes a reduced-scale version of the recharge map.”