Council hears detailed briefing on longstanding nitrate, uranium contamination and treatment options

Marty, a utility department staff member, told the council the city has identified a long-running "nitrate legacy" in its groundwater and outlined sampling results, treatment steps and costs, saying the issue requires both technical remediation and behavioral change. "We spent about $15,000,000 to get [ASR] done," Marty said, referring to the city's aquifer storage and restoration work as a short-term measure to protect potable supplies.

Marty summarized why the community faces the problem: about half of the city's water comes from Platte River recharge (he said the travel time is about 50 years), with the other half from rainfall and irrigation return. He said isotope testing and other studies point to commercial fertilizer (anhydrous ammonia) as the primary source at several monitoring sites and that the city has taken steps including shutting down wells that exceed the nitrate maximum contaminant level (MCL). "When a well exceeds 10 milligrams per liter or the MCL, we shut down the well. We've shut down 8 wells so far," Marty said; he added that replacement and safety upgrades for such wells run about $600,000 each and that the city has recorded about $4.8 million in lost capital infrastructure to date for those wells.

Marty described broader damages and costs the city has borne from contamination and legacy industrial sites, saying the water department faced about $25,000,000 in present-worth costs between 1986 and 2008. He said an ASR short-term plan was adopted to ensure potable supply while longer-term management — including best-management practices for fertilizer application, irrigation changes, soil testing and water conservation — is pursued. "We can't get rid of the problem. We're not gonna be able to necessarily clean it up. But if we don't stop adding to it, we never clean it up," Marty told the council.

He also discussed uranium findings. Marty said some sampling showed uranium concentrations as high as 10 times the drinking-water standard in parts of the wellhead protection area and explained that increased biological activity related to nitrates can mobilize naturally present uranium. He described health risks generally associated with elevated nitrates (including infant methemoglobinemia, commonly known as "blue baby syndrome") and said research is ongoing into links between nitrates, pesticides and cancer.

Council members asked about local programs and incentives Marty described: the city offers rebates for rain sensors and smart sprinkler controls and provides some soil-testing incentives to encourage best practices. Marty said the city has done extensive sampling (more than 1,000 water samples over the program) and mapping, and that some of the most contaminated areas were identified in a 2011 map that the city uses as a baseline but that additional sampling and modeling will be needed going forward.

Marty urged support for continued academic research and for policies and outreach to reduce excess fertilizer use and irrigation. He summarized the core policy dilemma: "Should the polluter pay? Should the NRDs pay? Should the federal government pay?" he asked, adding that addressing the legacy will likely require multiple funding sources, continued monitoring and behavior change among producers and residents.