Livestock farms raising cows or pigs create massive amounts of manure, which is regularly applied to nearby fields. Eventually, however, rain and snowmelt wash the manure off into rivers and lakes used for drinking water supplies.
That creates a problem for public water utilities. When utilities treat polluted water to kill bacteria, the disinfectants interact with manure and form a toxic byproduct called total trihalomethanes. Research shows exposure to these chemicals increases the risk of cancer as well as birth defects in babies whose mothers drank contaminated water.
Water systems must keep levels of total trihalomethanes at or below the Environmental Protection Agency’s maximum contaminant level of 80 parts per billion. But, the nonpartisan Environmental Working Group found more than 122 million people drink water contaminated above the federal limit. In all, the group discovered unsafe levels in nearly 6,000 public water systems, including more than 100 in eight Mountain West states.
“Reducing the amount of manure and organic matter that's getting into the water in the first place is an easier way to fix the problem than relying on utilities removing these chemicals,” report author Anne Schechinger said.
She added that farmers could plant vegetation buffer strips on their fields to reduce the flow of manure runoff. But those investments cost money, and the Trump administration’s freeze on federal funding doesn’t help, Schechinger said.
“There are billions of dollars from the Inflation Reduction Act that are supposed to be going to farmers for conservation practices that can reduce manure getting into streams and rivers and other sources of drinking water,” she continued. “And it's just all been frozen.”
The Mountain West state with the most water systems showing unsafe levels of total trihalomethanes is Colorado (41). That’s followed by Arizona (22), New Mexico (14), Utah (10), Wyoming (5), Idaho (4), Montana (4), and Nevada (2).
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, KUNC in Colorado and KANW in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.
