Lower South Boulder Creek Stream Management

Project Description

Flowing nine miles from the mouth of Eldorado Canyon to its confluence with Boulder Creek, Lower South Boulder Creek is a transitional Front Range stream that changes from cold to warm water as it flows out of the canyon toward the plains. This gradient habitat supports diverse aquatic organisms, including 21 species of fish. The City of Boulder's Open Space and Mountain Parks (OSMP) department manages high quality riparian forests, wetlands, and mesic grasslands along the creek; these lands provide essential habitat for various plants and animals, including federally threatened and endangered species.

Historic water development and land use such as gravel mining, urbanization, and stream channelization, have adversely impacted in-stream habitat and restricted the creek's ability to access its floodplain. The creek is also a complex web of water rights and flow management issues, as it contains at least 20 ditches and diversion structures. These diversions, and other physical impediments to low-flow passage, produce no-to-low in-stream flows during much of the winter months.

Biohabitats is working with Boulder Flycasters and key stakeholders to significantly improve low-flow conditions and the overall ecological health of Lower South Boulder Creek. For Phase I, the team developed and implemented a communications plan, which included formation of a steering committee and interaction with critical state organizations. Biohabitats also compiled and categorized existing information and reviewed past evaluations and assessments to understand and map existing conditions, including physical infrastructure, fish passage, and water use efficiency. Biohabitats is now developing metrics for the stream health assessment in Phase II and evaluating low-flow conditions, all to identify prioritized phased projects. Biohabitats is working with students from the Colorado School of Mines to develop preliminary design of diversion modifications.