BALTIMORE— A new report from the Environmental Working Group (EWG) reveals that 122 million Americans, including many in Maryland, are drinking water contaminated with high levels of cancer-causing chemicals known as trihalomethanes (TTHMs). The study, which analyzed water systems from 2019 to 2023, found that 6,000 systems nationwide had unsafe TTHM levels at least once, often due to runoff from livestock factory farms.
In Maryland, the city of Baltimore and the Washington Suburban Sanitary Commission exceeded the Environmental Protection Agency’s (EPA) maximum allowable limit of 80 parts per billion (ppb) for TTHMs a combined 255 times during the study period. TTHMs, formed when chlorine disinfectants react with organic matter like manure in water, are linked to serious health risks, including colon and bladder cancer, heart defects, and stillbirths.
“You can live miles and miles from ag, but still have ag pollutants in your drinking water,” said Anne Schechinger, agricultural economist and Midwest director of the Environmental Working Group. “You might see this report and think, ‘Well I live in a city. I’m not anywhere near ag.’ That doesn’t mean that livestock manure is not impacting your drinking water.”
The report highlights manure runoff from concentrated animal feeding operations (CAFOs) as a major contributor to TTHM contamination. In Maryland, agricultural runoff from nearby farming regions can pollute surface water sources, such as reservoirs, that supply urban water systems like Baltimore’s. The problem is exacerbated by insufficient regulation of manure management, with only 2% of animal feeding operations required to have EPA-approved manure management plans.
Call for Policy Changes and Consumer Action
Schechinger argued President Donald Trump could reduce pollution by unfreezing funds helping farmers use healthier agricultural practices. Funds are currently frozen as Trump’s Department of Government Efficiency tries to cut spending it views as wasteful. “We can be putting more conservation practices on farm fields, like stream buffers or grass waterways, that really stop the flow of manure into water,” Schechinger recommended. “That’s something that was intended for this year, but the Trump administration has frozen the majority of agricultural conservation funding.”
The EWG report calls for stricter EPA regulations on manure management, increased funding for advanced water treatment systems, and incentives for sustainable farming practices like cover crops and stream buffers. In Maryland, where six of the top 10 states with high TTHM levels have significant livestock operations, such measures could reduce contamination risks.
For consumers, Schechinger added that using a water filter can help remove chemical runoff from drinking water. Carbon-based filters, such as pitcher or faucet-mounted systems, are effective at reducing TTHM levels and are recommended for households concerned about water quality.
Broader Implications and Challenges
The issue extends beyond Maryland, affecting 49 states and Washington, D.C., with some systems reporting TTHM levels as high as 300 ppb. Texas, California, and Florida are among the hardest hit, with Texas alone having over 700 systems exceeding the EPA limit. Rural areas near factory farms face the highest risks, but urban systems like Baltimore’s show how far pollutants can travel through water sources.
The Trump administration’s freeze on agricultural conservation funding, part of broader deregulatory efforts, has drawn criticism for undermining efforts to curb manure runoff.Additionally, the EPA’s recent withdrawal of proposed PFAS regulations signals a shift away from stringent environmental protections, raising concerns about future water safety measures.
Maryland officials have yet to announce specific plans to address the TTHM violations in Baltimore and the Washington Suburban Sanitary Commission. However, the EWG’s findings underscore the need for immediate action to protect public health and ensure safe drinking water for all residents.
