Under the Urban Drainage and Flood Control Districtís Master Planning Program, stormwater planning studies are periodically conducted to assess detention, water quality, and drainageway needs in watersheds across the Denver metro area. A Major Drainageway Plan (MDP) is currently underway for the Newlin Gulch watershed. The area was previously studied in an Outfall Systems Plan, published in 1993 by Kiowa Engineering Corp.

Newlin Gulch originates in unincorporated Douglas County, located along I-25 about 3 1/2-miles north of Castle Rock. The creek and its tributaries flow northeast through areas of Castle Pines, unincorporated Douglas County, and the Town of Parker before joining Cherry Creek near Challenger Park in the Town of Parker. The Newlin Gulch watershed area is approximately 15 square miles (see study area map).

West of I-25, the upper third of the watershed was recently annexed by the City of Castle Pines and is slated for residential and commercial development. East of I-25, the watershed includes the majority of the planned Canyons development, also in Castle Pines. The middle third of the watershed starts upstream of the new Rueter-Hess Reservoir, operated by Parker Water and Sanitation District, and ends at Mainstreet in the Town of Parker. A portion of the Parker Homestead development is located in the watershed just north of Rueter-Hess. The lower third of the watershed, located north of Mainstreet, is nearly fully developed by the Stonegate Village and Challenger Park Estates developments, among others.

A key goal of the study will be to update hydrology based on the most current land use information for existing and future conditions and to assess impacts associated with Rueter-Hess Reservoir. Flood hazard issues along Newlin Gulch will be identified and recommendations developed to address problem areas. Newlin Gulch is a sandy, ephemeral channel that is highly susceptible to instability and erosion. With the scattered development and large undeveloped areas in the watershed, the study will place an emphasis on minimizing the impacts of future development as they relate to channel stability. Measures will be considered to protect the channel from degradation and preserve natural stream functions.

The primary project deliverable will be a Major Drainageway Plan. The Major Drainageway Plan will include conceptual design of recommended improvements in the watershed, including estimated costs. The completed study will serve as a guide for implementing drainage improvements within the watershed. Intermediate deliverables will include updated Baseline Hydrology and an Alternatives Analysis.

The project is funded by the Urban Drainage and Flood Control District (UDFCD), Douglas County, and the Town of Parker. Other stakeholders that will be invited to participate in the process include the City of Castle Pines, Parker Water and Sanitation District, the Colorado Department of Transportation, and the Cherry Creek Basin Water Quality Authority.