Bill would test use of state's rainwater

DENVER • Water rights battles have raged in Colorado for decades, but a bill being considered at the state Capitol could ease some of the tensions between highly populated urban communities and agriculture-dependent rural areas.

HB 1129, by Rep. Marsha Looper, R-Calhan, would establish a pilot program to determine whether sophisticated rainwater collection systems can be a sustainable water source without infringing on downstream water rights of farmers and ranchers.

Looper said according to projections, Colorado will have 3 million new residents by 2035. By 2030, groundwater supplies will be decreased by 3 billion gallons on the Western Slope and 35 billion gallons on the Front Range. That could mean that water battles will become even fiercer in coming years.

"We have got to find another way to augment the loss of the ground water. Rainwater harvesting is a technique that we think might get us there," Looper said. "In Eastern El Paso County, where all the growth is, this is going to be massively important for us to continue to grow and develop."

Under Looper's bill, the Colorado Water Conservation Board and the State Engineer's Office would be authorized to construct 10 experimental groundwater collection facilities across the state over the next decade.

One of the most common methods, Looper said, is to build a large gutter collection network that funnels rainwater into an underground storage facility, commonly installed under residential suburbs. Seven states have similar programs.

The water collected would only be used for landscaping and irrigation, since it wouldn't be chemically treated to make it drinkable. During testing, the water board would also be required to monitor how much water is collected and to then supply an equal amount into streams and tributaries.

That way, Looper said, none of the stakeholders downstream would be losing a drop of water for the duration of the program. At the same time, the water board would have to carefully measure how much precipitation would have made it into streams during the same period. The idea, she said, is to prove that rainwater collection doesn't affect the normal water flow, and then to gain approval for a more widespread rainwater collection program.

"We have to be cautious, because we're up against 120 years of water law. There are those naysayers that are saying this is going to affect the stream system," Looper said.

She said a recent study by the water board found that only 3 percent of rainwater contributes to normal river flows, while the other 97 percent either evaporates or is taken up by plants.