Hydrology

The Preserve is located entirely within the Black Earth Creek Priority Watershed, which is a part of the larger Lower Wisconsin River Watershed Complex. An unnamed tributary of the Black Earth Creek flows from northeast to southwest through the eastern and southern borders of the Preserve. The headwaters of this tributary are located near the junction of Otto Kerl Road and Enchanted Valley Road, in the Township of Berry. For lack of a name, this tributary will be referred to as the Otto Kerl Creek when referenced within this document. Although at the present time this creek functions locally as a stormwater outflow conduit, it was present on this site at the time of Euro‐ American settlement, and its presence was recorded by surveyors in 1832 (Figure 1).

Hydrology Figure 1

Like many tributary streams in southwestern Wisconsin, the Otto Kerl Creek has been disturbed by human activities during post‐settlement times. Conversion of prairie to row crop agriculture over the previous 180 years has led to increased surface runoff and erosion, which has increased the frequency and amplitude of high‐discharge flooding events, deepening and widening the stream bank profile. Prior to Euro‐American settlement, wet prairie and sedge meadow vegetation bordering the Otto Kerl Creek (documented by land surveyors in 1832) captured and retained surface runoff, which then entered the creek gradually rather than abruptly. However, unlike many of the tributary streams in this and other southwest Wisconsin watersheds, the section of the Otto Kerl Creek transversing the Preserve lacks the deep layer of accumulated agricultural sediment covering the Holocene alluvial soils that support wet prairie and sedge meadow vegetation (Booth et al. 2009) at the southern end of the east valley (Figure 2).

Hydrology Figure 2

The confluence of the Otto Kerl Creek with the Black Earth Creek is located approximately one‐quarter mile southwest of the Preserve. From there, the Black Earth Creek merges with the East Branch of Blue Mounds Creek approximately 10 miles northwest of the Preserve. The Blue Mounds Creek empties into the Wisconsin River approximately 1.75 miles northeast of the Village of Arena.  Owing to its size, position in the watershed, and the diverse assemblages of wetland vegetation that it supports, the Preserve provides valuable ecosystem services (sensu Costanza et al. 1997) to the Black Earth Creek Watershed, particularly in terms of water quality enhancement. Additional hydrological input to the Preserve comes from several natural springs located throughout the property. Recharge of wetland hydrology occurs as 1) surface runoff (the west valley has a 560‐acre drainage basin and the east valley drainage basin exceeds 800 acres), 2) springs and seeps located throughout the property, 3) bank overflow from the Otto Kerl Creek, which does not occur annually, 4) intersection of low areas with the groundwater table.

When the property was acquired in 1987, the northern portions of the east valley had been artificially drained for agricultural purposes by tiling and ditching. Hydrological loss was exacerbated by wildfire suppression, which indirectly facilitated successional progression to shrub‐carr and lowland forest. In the absence of wildfire, fast‐growing tree and shrub species with high evapotranspiration rates, such as willows (Salix spp.), box elder (Acer negundo), cottonwood (Populous deltoides), honeysuckles (Lonicera spp.), and dogwoods (Cornus spp.), invaded the site and contributed to hydrological losses. Together, these hydrological disturbances uncoupled remnant sedge meadow and wet prairie vegetation from their hydrology and facilitated invasion by reed canarygrass (Phalaris arundinacea).

Reed canary grass (Phalaris arundinacea) contributes to loss of important sedge medow and wetland communities

Reed canary grass (Phalaris arundinacea). Photo by Christopher Noll, UW-Steven’s Point Herbarium

To restore wetland structure and function to the east valley, drainage tiles were probed, smashed, and then buried by a backhoe in 1994‐95, and in 2007 a ditch fill/scrape construction project, funded in part by the USFWS, was undertaken to restore hydrology to the sedge meadow remnant. In the winter of 2008‐09, these efforts were followed up by tree and brush clearing, funded in part by the USDA‐NRCS Wildlife Habitat Incentives Program (WHIP). Beginning in the spring of 2009, reed canarygrass control, funded in part by the WDNR Aquatic Invasive Species (AIS) Program, was initiated and so far has yielded encouraging results. This particular project, broad in its scope, is one example of how the Swamplovers Foundation, Inc., working in concert with government agency programs, ecological consultants, and contractors, has been able to successfully restore and rehabilitate ecosystem functioning at the Preserve, not as isolated individual projects but as an integrated, concerted effort within a landscape‐scale context. Sedge meadow restoration in the east valley will be tied into additional rehabilitation and enhancement projects being conducted in adjacent sections of the Preserve (funded in part by WDNR Landowner Incentives Program (LIP) and Turkey Stamp Program) to provide Wisconsin’s indigenous flora and fauna with a continuum of habitats along the wetland to upland continuum.

An ephemeral drainage ditch runs north to south through the low points of the west valley and typically has standing water during heavy rain events in the spring but is either dry or drawn down during most summers. This ditch empties into the newly‐constructed (summer 2010) six‐acre waterfowl production scrape pond at the south end of the west valley and contributes to hydrological input for remnant sedge meadow wetlands located on John Brooks’ property, immediately south of the Preserve.

A total of 22 natural and constructed ponds occur throughout the Preserve. The ponds of the east valley have an average concentration of total dissolved solids (TDS) of 282 ppm (SE = 13.1, range {256 ppm – 317 ppm}) and an average conductivity of 403 µS (SE = 19.4, range = {364 µS – 454 µS}). (Both sets of measurements were recorded in July 2009, at an average water temperature of 21.4°C.)