Trinidad / Denver — Staff from the Colorado Energy and Carbon Management Commission (ECMC) briefed commissioners July 9 on a two-part study directed by Senate Bill 23-186 that mapped methane seepage in the Raton Basin and evaluated water quality from coalbed methane (CBM) produced water for potential beneficial reuse.

The field and laboratory study, led by Rick Allison (ECMC groundwater investigation lead) and Chris Sanchez (area environmental protection specialist), is summarized in a report published by ECMC on June 18. The study has two components: aerial and pedestrian methane-seep mapping, and targeted water-quality sampling and analysis of CBM-produced waters in the Los Animas County portion of the basin.

Key findings — seeps: ECMC and contractor aerial surveys covered about 75 square miles and detected 99 preliminary seep locations; staff gained access to 45 of those and measured 29 seeps with measurable methane flux. Total measured methane seepage from those seeps was 4,177 kg/day, and seven of the measured seeps accounted for 88 percent of the total measured flux. The largest single seep (SSA 65 in the report) emitted roughly 1,758 kg/day. The team used helicopter-based methane detection, pedestrian flux chambers and shallow soil-gas sampling. Staff emphasized that the mapped seepage represents a subset of the basin and recommended the work as a benchmark for future monitoring.

Key findings — water quality and reuse: ECMC evaluated existing operator sampling required by Rule 909(j) (water sampled for water placed in pits) and collected an expanded analyte list of 24 additional samples. Findings show variable water quality across the basin: salinity (sodium and chloride) is high in a central-southern “hot spot,” fluoride concentrations persistently exceeded EPA secondary and drinking MCL levels in many samples (half the samples in the extended dataset exceeded the EPA MCL of 4 mg/L), and barium exceeded drinking water MCLs in a portion of samples. Some inorganic contaminants, including radium and benzene, were above EPA MCLs in a subset of samples. PFAS were detected at trace levels in six of 24 new samples; detected compounds did not exceed the then-current EPA MCLs reported by staff.

Implications for reuse: Staff evaluated potential beneficial uses (livestock/wildlife watering, irrigation, dust suppression/firefighting) and concluded the waters are not generally fit for untreated irrigation due to high sodium adsorption ratios and salinity, which can damage soils. Livestock or wildlife watering may be feasible at some sites but would require site-specific characterization and possibly treatment (fluoride, barium and other parameters of concern). For dust suppression, high sodium chloride–dominated brines are generally inferior to calcium/magnesium chloride brines and may produce more PM10 dust; produced waters in the Raton Basin would likely be on the high end of dust generation without treatment.

Mitigation of seeps: Mitigation options for large seeps include soil-gas recovery (similar to radon mitigation systems) to reduce root-zone methane and rehabilitate vegetation, and active capture/destruction of methane to reduce greenhouse-gas emissions. Staff said seep mitigation typically operates in shallow soils and does not generally produce water; produced water is mainly a result of coalbed methane production.

Partners, next steps: ECMC worked with CDPHE’s Water Quality Control Division (WQCD), the Air Pollution Control Division (APCD) Office of Innovations, contractors (Insulm LLC and Dolan Integration Group), the Colorado Energy Office and local landowners. Staff said they plan to pursue additional methane mapping in areas they were unable to cover, and they recommend ongoing characterization of waters if any beneficial reuse proposals are advanced. ECMC noted that any surface-water discharge would be regulated by CDPHE’s Colorado Discharge Permit System and subject to effluent limitations designed to protect downstream uses.

Ending: The report gives regulators a baseline for future monitoring and lays out site-specific mitigation and water-quality characterization steps needed before any beneficial reuse. ECMC staff said they will continue engagement with local governments and partner agencies as the next steps unfold.