Colorado oil and gas companies used toxic chemicals prohibited under state law in operations involving dozens of wells on either side of the Rocky Mountains over at least the last 18 months, a Capital & Main investigation found. Disclosures to the state’s fossil fuel regulator showed operators combined banned substances with water, sand and other chemicals as part of a process known as hydraulic fracturing, or “fracking.” …  Physicians and environmental groups say that it’s important to disclose such substances because drilling machinery penetrates aquifers without any concrete casing around the bit, potentially exposing groundwater to contamination. 

Other water contaminant news:

• The Guardian (U.K.): Trump EPA seeks to weaken scrutiny for some of US’s most toxic chemicals
• Newsweek: Drinking water contamination report raises questions
• Waterkeeper Alliance: News release: Waterkeeper Alliance files FOIA request to uncover EPA’s backroom dealings on toxic “forever chemicals” in drinking water
• Santa Monica Daily Press (Calif.): Santa Monica Council approves water quality report showing safety compliance
• Maven’s Notebook: Blog: Ag expert panel organizes its work and requests additional data at first working group meeting