Town to meet half of water demand by 2020, plan says

As of this year, 91 percent of the town's water is supplied from deep nontributary wells in the Denver Basin aquifer system, said Will Koger, utilities engineer for the town.

But each year the level of the aquifer drops and will require new and more expensive wells, Koger said.

The aquifers are nonrenewable water, Koger said, and their declining water levels reduce pump efficiency. Pumping costs for existing Denver Basin wells will increase about $21,000 annually, he said.

The answer lies in a plan to find new sources of renewable water, Koger said.

Renewable water comes from streams and rivers, he said. Each year they are replenished with the melting snow and by rainfall.

Koger presented the 2000 Water Facility Plan Aug. 21 to the Castle Rock Planning Commission and Thursday to the Castle Rock Town Council, which voted unanimously to approve the plan.

The plan is a vision of the ability to meet water needs in the next 20 years and works in conjunction with the town's master plan, which is being updated.

At ultimate development, Castle Rock could have a maximum demand of about 70 million gallons of water a day, the report said. To provide that water, existing treatment plants need to be expanded or replaced with larger plants.

A future with a possible 186,000 residents means Castle Rock will need to develop alternative water resources through water rights and expansion of alluvial well systems and exchange rights in the South Platte River Valley, he said.

Such an exchange would trade treated wastewater effluent from East Plum Creek for surface water from the river and could supply as much as 20 percent of water demand and reduce groundwater consumption, the report said.

The development of existing water rights in East and West Plum Creek could provide the town with and 12 percent of its projected ultimate water demand. The remaining water needs could be met with joint development and shared use of a raw water storage reservoir with other water districts or municipalities in Douglas County, the report said.

"We have done a 200-year water study," Koger said. "There's plenty of water in the area."
But what needs to change is the town's reliance on rapidly dwindling nonrenewable water sources like the aquifers, he said.

To meet the projected consumption in the next 20 years, the town would need to budget more than $52 million to upgrade existing wells, create regional treatment plants, purchase water rights and maintain existing equipment, Koger said.

Some existing plants will need to be phased out, he said.

The water treatment plant at Dawson Ridge should be decommissioned when demand for the service area exceeds the plant's capacity of 1.3 million gallons a day, the report said. The P.S. Miller water plant has limited expansion potential and should be eliminated in 10 to 15 years because the plant is surrounded on all sides by the Plum Creek Golf Course.

"This is a plan, not a budget allocation," Koger said to the town council. "The $52 million would provide the skeleton to prepare for 186,000 people."