Aurora is moving ahead with its $750 million plan to reuse return flows and provide enough additional water to support its needs well into the next two decades. In the process, its Prairie Waters Project is attracting attention across the West as a way to provide additional water without drying up more farms or increasing transmountain diversions. "More than 90 percent of our water supply can be used, and reused to extinction," said Mark Pifher, deputy director for Aurora Water.
Aurora brings in about 60 percent of its water from the Colorado River or Arkansas River basins. Additionally, most of its flows from the South Platte River basin are the consumptive use portion of former agricultural water. All of the return flows from that water are classified under state water law as "fully consumable," meaning the city can capture it and reuse it, Pifher said. Those flows are now primarily leased to downstream farmers, but after the drought of 2002-03 nearly drained Aurora's reservoir supplies, the city decided to look seriously at indirect reuse of the flows...
While Aurora is prevented from more transfers from the Arkansas River basin by intergovernmental agreements, it still has undeveloped rights in the Colorado River basin and could still claim additional rights. The city decided on Prairie Waters as the most cost-effective way to deliver new water. By 2010, the city will have finished a system capable of delivering up to 10,000 acre-feet annually - 3.26 billion gallons. Aurora reclaims water from the South Platte because its wastewater - like many other cities in and around Denver - is handled by the Denver Metro district. The discharge point is several miles upstream of where Aurora plans to build wells and recharge basins...
Ground will be broken for a $190 million treatment plant later this month. After that, a system of wells and pipelines will be completed. Water will be taken from alluvial wells northwest of Brighton, and pumped into nearby recharge basins that create an underground barrier 50 feet deep. The water from the wells is treated naturally through river bank filtration as it flows along the South Platte, as well as from the ground as it flows. The wells will be placed to allow about 10 days of travel time through the aquifer, according to engineers from CH2M Hill, consultants on the project. The two recharge basins, which cover about 200 acres each, provide additional filtration. From there, water will be pumped through a 60-inch-diameter pipeline 34 miles to Aurora Reservoir. Three pumping stations are required along the route, lifting the water about 1,000 feet in elevation. The treatment plant at the end of the line will use several processes - softening, ultraviolet light, filtration and charcoal adsorption - to further treat the water. At that point, it will be blended with fresh water sources for taste and odor issues...
Environmental groups have praised the project as a model for reuse, and Aurora has worked on agreements with agricultural users such as the Central Colorado Conservancy District to help meet farmers' augmentation needs...
Eventually, Aurora's current water rights could yield more than 100,000 acre-feet through Prairie Waters and other improvements. Prairie Waters is intended to meet Aurora needs through 2024. By that time, a second pipeline could be added and other improvements in the water system made. Aurora has plans to eventually build another reservoir east of Aurora Reservoir.
