High Creek Fen is a unique groundwater-fed wetland located in South Park, Colorado. Previous research has studied the hydrology of the fen however groundwater sources to the fen have not been identified. This has become a priority because land use changes in the South Park are exacerbating groundwater resource issues. Hydrologic modifications to High Creek Fen could have dramatic ecological effects since it supports globally rare plants and invertebrates. In addition, the Nature Conservancy is interested in identifying additional preservation lands to protect the hydrologic and ecologic integrity of High Creek fen. This research employs a variety of methods to identify the groundwater sources High Creek Fen. First, the two primary groundwater discharge areas were identified using geologic and topographic maps and information from previous studies at High Creek Fen (Brand and Carpenter, 1999; Appel, 1995; Johnson, 1996). Next, groundwater discharge was characterized using groundwater level measurements at piezometer nests and surface water discharge. The groundwater discharge data supports the hypothesis that there are two primary discharge areas at High Creek Fen and therefore two different groundwater sources.

A regional groundwater contours map, in conjunction with geologic maps of the area (Tweto, et al., 1976; Behre, et al., 1939), have been used to establish groundwater source locations. In the final phase of this research, analysis of the stable isotopes of water, ädeuterium and äoxygen-18, will be used determine a connection between the groundwater sources and groundwater discharge at High Creek Fen. If the source and discharge samples do not have a similar isotopic signature the sources have been misidentified, and the regional groundwater information will be re-evaulated. The methods for identifying groundwater sources to High Creek Fen add to a knowledge gap in the scientific literature with respect to the groundwater hydrology of wetlands. In addition, characterizing the hydrology of High Creek Fen provides the foundation for studying other aspects of these unique and diverse ecosystem.