Water Quality & the Recycled Water System

Denver Water is building a non-potable recycled water system, the largest in Colorado, that will treat and deliver up to 17,000 acre feet (af) of water per year for industrial and outdoor irrigation use when it is completed. That amount of recycled water can free up enough drinking water resources to serve 36,000 households. The treatment plant has been in service since 2004, and in 2007 the system supplied nearly 6,000 acre feet to first adopters. The addition of Lowry and Stapleton large irrigators in 2008 will increase use to 9,000 af.

Recycled water is produced by taking treated wastewater that otherwise would be discharged into a river or stream and treating it again so it can be used for non-drinking purposes, such as irrigation for parks and certain industrial uses. The United States has been recycling wastewater for more than fifty years. Denver Water's recycled water treatment process is very similar to the process used to treat drinking water, although the end result has a residue of salts and other elements that make it not drinkable. The production from the recycling plant must satisfy government standards for non-potable water. In Colorado, the quality of recycled water is regulated by the Colorado Department of Public Health and Environment.

Some people have expressed concerns that the wastewater effluent being discharged into the South Platte from the Metro Wastewater Treatment Plant (the source of the water treated at the recycle plant) might be contaminated with radioactive and other hazardous wastes. They have speculated that such contamination might be coming from Lowry Landfill, a Superfund site currently undergoing clean-up under the supervision of the U. S. Environmental Protection Agency.

Groundwater collected at Lowry Landfill is in fact discharged to Metro, after pre-treatment on-site at Lowry. However, the water discharged from Lowry makes up less than one-hundredth of a percent of the water Metro processes. And more importantly, extensive scientific testing by the EPA over the last 15 years has not identified any elevated risk from the Lowry discharge, and there is no evidence that significant radioactive waste was ever dumped there. As the Lowry Landfill FAQ puts it, "radioactive material at Lowry Landfill is present at background levels that are consistent with naturally occurring and man-made radiation found throughout the western United States." (For more information, visit the Lowry Landfill web site.) In 2000, the EPA's Inspector General issued a formal report which "found no apparent credible evidence" that high levels of radionuclides were present at Lowry. Studies have determined time and time again that there is no increased risk from the groundwater being discharged from Lowry to Metro.

Long before the treated wastewater reaches the Water Recycling Plant, the EPA monitors the discharge from Lowry to the Metro treatment facility. The EPA has determined that there is no risk of radioactive contaminants from the groundwater being collected at Lowry Landfill itself, even before pre-treatment. The federal agency also monitors groundwater before it is collected at Lowry for pre-treatment via "early warning wells." Water quality is monitored in these wells six months prior to collection and pre-treatment. None of these tests, conducted quarterly, have showed any problems with radioactive or hazardous contaminants.

The water is diluted at Metro and tested again, with negative results, during treatment. It's tested yet again when being treated at Denver Water's new recycling plant. None of those tests have substantiated the claims of radioactive or other hazardous waste.

More information:

Joe Sloan at 303.628.6320 or joseph.sloan@denverwater.org