The Upper Arkansas Water Conservancy District board of directors advanced a project to increase the storage capacity of DeWeese Reservoir on Grape Creek in Custer County.
District staff and consultants have completed a phase one feasibility study for the proposed expansion, and the board of directors authorized Project Manager Gracy Goodwin to pursue $210,000 in grant funding for a phase 2 study at their meeting Thursday, Nov. 13, in Salida.
Goodwin said the project qualifies for a Colorado Water Conservation Board grant because it meets multiple State goals, including increasing water storage capacity. The grant would cover 50% of the cost of the phase 2 study.
DeWeese Reservoir was built in 1903 to store irrigation water. A previous study conducted by the Upper Ark District, the Bureau of Land Management and the DeWeese-Dye Ditch and Reservoir Co. analyzed flow efficiency and management.
The irrigation efficiency study concluded that more storage capacity is needed, in part to sustain flows needed to support fishery health in Grape Creek.
The phase 1 study examined the physical, hydrological, environmental, legal, financial, social and economic feasibility of expanding reservoir capacity by increasing the height of the dam by up to 6 feet.
The phase 1 study determined that a 4-foot increase in dam height might be feasible and would provide about 1,100 acre-feet of additional storage, Goodwin said. The Upper Ark District would get 60% of the additional capacity, and the DeWeese-Dye Co. would get 40%.
The phase 2 study, she said would include a geotechnical analysis to determine the suitability of subsurface materials for supporting a larger dam as well as a structural evaluation of the dam and the stability of the adjoining rock formations.
If everything else checks out, she added, the phase 2 study will include engineering to produce 30% design drawings.
Dam History
According to the DeWeese-Dye website, Dall DeWeese and C.R.C. Dye incorporated the DeWeese-Dye Ditch and Reservoir Company to bring water from Grape Creek to the Lincoln Park property they owned.
The partners planned on developing the property, called Fruitland, and built the DeWeese-Dye Ditch to deliver irrigation water to the property.
“They soon realized there was not enough water in Grape Creek to maintain irrigation in the late summer and fall. In 1902 they started construction on a dam northeast of Westcliffe.” With the completion of construction in 1903, DeWeese Reservoir was created.
During the 1930s, the state prison in Cañon City supplied laborers to construct two 6-foot extensions to the top of the dam and increase the size of the reservoir.
In the mid-1990s, the State Engineer condemned the dam additions, so company shareholders decided to borrow money to reconstruct the dam’s top 12 feet. The work was completed in 1999.
Photo: The crew that built the DeWeese Dam stands atop the dam as it nears completion (photo courtesy of Deweese-Dye Ditch and Reservoir Co.).
