Mapping and Characterization of Springs in Brown and Calumet Counties

Flow from groundwater springs and the associated emergent environment provide important habitat for a variety of terrestrial and aquatic plant and animal species. Springs also contribute source water to streams. Historically natural springs have provided domestic and agricultural water supplies and in some cases are still used for such purposes and for commercial water bottling operations. Under Wisconsin Act 310, high capacity wells are required to be permitted by the Wisconsin Department of Natural Resources (WDNR). The permitting process is used to determine whether high capacity wells will impact groundwater or other important water resources including natural springs. Springs discharging greater than 1 cubic feet per second (cfs) throughout 80% of the time are to be protected. The protection cutoff of 1 CFS may, however, have an undesirable effect on the ecology of small, low-discharge springs that provide critical habitat for certain species. These smaller springs will be more susceptible to groundwater depletion than larger springs. Currently, the WDNR does not have a centralized database of spring locations and there is very little information on spring flow characteristics. Spring locations appear on topographic maps, soils maps and other resource inventory maps for Brown and Calumet Counties. However, there are inconsistencies between map sources and no comprehensive natural spring survey exists for the area studied.

Objectives

The main goal of this study was to inventory and characterize springs in Brown and Calumet Counties, Wisconsin, with an emphasis on larger springs as defined in 2003 Wisconsin Act 310. Specific objectives were to: 1. Map the location and determine the outflow characteristics of springs; 2. Quantify the flow amount and duration of springs with significant flow; 3. Measure the geochemical and water quality characteristics of springs with significant flow; 4. Determine spring outflow age and hence relative travel time through the subsurface; 5. Inventory landscape and biological characteristics of spring sites with significant flow.

Methods

An inventory and assessment of springs was conducted between April, 2005 and August, 2006. Reconnaissance was performed to determine spring locations and discharge was qualitatively assessed. The geolocation of each spring was documented using GPS. Five springs with larger and persistent flows were chosen for detailed study—two were located in Brown County and three were located in Calumet County. Biweekly monitoring of the five selected springs began in September 29, 2005 and concluded August 28, 2006. Baseline information that was collected included pH, temperature, specific conductivity and flow. Discharge measurements were made using the volumetric measurement method, measuring stream cross section and velocity, or using a calibrated portable weir plate. Grab-samples were collected six times at selected spring outflows and were used to determine anion (sulfate, chloride, nitrate, nitrite and phosphate) and element (Ca, Mg, Zn, Na, K, Fe) concentrations, and alkalinity. These samples were collected in September 2005, January 2006, March 2006, June 2006, July 2006 and August 2006. Apparent groundwater recharge age-dates were determined for each site on samples collected on October 1, 2005 and June 3, 2006 using ultra-trace chlorofluorocarbons (CFCs) techniques. CFC samples were analyzed and interpreted at the Trace Gas Analysis Laboratory at UWStevens Point.