Water, Infrastructure and Supply Efficiency: WISE

Seventeen entities, including Denver Water, have joined forces on a project that will supply customers with more water while minimizing the need to buy new water rights.

Denver Water is moving forward with a partnership called WISE, which stands for Water, Infrastructure and Supply Efficiency. If approved, the partnership will provide new supply by combining unused capacities in Aurora Water’s Prairie Waters Project with unused water supplies from Denver and Aurora. Then, during the years Denver and Aurora don’t need all of that water, 10 Douglas County entities that are part of the South Metro Water Supply Authority will be able to buy the unused water to help reduce its reliance on nonrenewable groundwater.

The partnership has not been finalized and much work remains. But if all goes as planned, Denver Water will start capturing its unused water and selling it to South Metro in the next few years.

This cooperative effort is rare in Colorado, which divvies up water based on a first-in-time, first-in-line style of water rights (prior appropriation).

But WISE is different.

After the 2002 drought, Aurora Water knew it needed to find more water supplies and fast. If they had had another horribly dry year after 2002, they would’ve been in trouble.

So Aurora, which is one of the largest water providers in the state, built the Prairie Waters Project. The $653 million project began operating in fall 2010, increasing Aurora’s water supply by 20 percent.

The project allows Aurora Water to collect South Platte River water it owns from wells near the river’s bank just north of Brighton. The water is then piped 34 miles south to a new purification facility near Aurora Reservoir, where it is treated and delivered to Aurora customers.

Such a massive project required an immense amount of infrastructure. And during the winter, when people aren’t watering their lawns and putting such a demand on the system, Aurora doesn’t need all of infrastructure.

Denver Water saw Aurora Water’s underused infrastructure as an opportunity to capture reusable water in the South Platte for a new reserve supply, which can be used during emergencies. At the project’s completion, Denver Water expects to capture about 15,000 acre-feet of unused supply — enough to serve almost 38,000 homes. When Denver Water doesn’t need that emergency supply, it plans to sell the excess to South Metro, which relies heavily on nonrenewable aquifers and wells.

Denver and Aurora’s WISE deliveries to South Metro could be as much as 10,000 acre-feet per year, on average, starting within the next decade, with an eventual total of 60,000 acre-feet of water per year, on average, to supplement its groundwater supplies.

The water that Denver will put into WISE is primarily reusable return flows from its Blue River supplies. No new diversions will need to be made in Denver’s mountain system to provide WISE water.

Denver Water’s role in the partnership stems from a decades-old request from the Board of Water Commissioners to cooperate with regional entities when looking for new supply instead of working with only one agency at a time. The Board also challenged staff to look at purchasing agricultural water, something this project will allow Denver Water to do.