An ongoing study of the effects of coalbed methane production water discharge on crops, soils and Tongue River water in Montana continues to find no harmful impacts. The study is funded by the Montana Board of Oil and Gas Conservation (MBOGC), an agency of the Department of Natural Resources and Conservation (DNRC).

Sodium levels in soils and crops are at or below initial concentrations that were found in 2003 when the program began, the study found. Approximately 3,000 CBNG wells have been drilled in the Tongue River drainage of Montana and Wyoming. The majority of the water from the wells is discharged to off-channel storage, beneficially used, treated prior to discharge or injected. Less than one-fourth is discharged untreated to streams through various state permits. Most of this CBNG water is discharged into the Tongue River above the Tongue River Reservoir. Because it mixes with the river water, it eventually makes its way to irrigated fields along the Tongue River drainage.

Montana authorities have long been concerned that excess salts contained in CBM-produced water would degrade the state's waterways and hurt agricultural interests in the southeastern part of the state. In a move to protect its waters and agriculturalists, the state adopted strict water quality standards for CBM operators. Those stringent rules have caused a number of Wyoming and Montana CBM producers to sue Montana (see NGI, Aug. 7, 2006).

The finding of this latest iteration of the study are similar to those released last year (see NGI, June 18, 2007).

The study, the Tongue River Information Program (TRIP), was designed to assess the impact of CBNG discharge water on crops, soils and river water downstream from CBNG water discharges. The soil and crop analysis portion of the project, the Agronomic Monitoring and Protection Program (AMPP), was funded by Fidelity Exploration and Production from 2003 to 2006. When the MBOGC took over the project in November 2006 it continued the soil and crop monitoring and included a Tongue River hydrologic component.

MBOGC engaged HydroSolutions Inc. as its principal contractor, along with Fehringer Agricultural Consulting, K.C. Harvey Associates and Schafer Ltd. This team of researchers measures crop yields, crop minerals (including sodium) and key properties in irrigated soils in the Tongue River drainage to detect impacts to irrigated crops and agricultural soils due to discharges associated with CBNG production. The hydrologic component reviews and analyzes state and federal data tracking Tongue River water parameters.

"The 2007 report of data collection and analysis on 12 properties along the Tongue River drainage shows crop yields are comparable to local county averages showing relatively consistent soil salinity or sodicity over time (on the properties where samples and analysis were conducted)," said Neal Fehringer of Fehringer Agricultural Consulting. He pointed out that two reference fields outside the Tongue River drainage are also studied in the same manner to see if trends are exclusive to the Tongue River drainage, or whether they are area-wide.

The TRIP has a hydrologic component designed to assess whether CBNG discharges are having a measurable effect on irrigation water drawn from the Tongue River. Water quality analysis of existing data shows that salt content (as defined by electrical conductivity) remains relatively constant at comparable stream flow rates before and after the beginning of CBNG discharges in 1999," said Tom Osborne, principal hydrologist with HydroSolutions.

Last fall a state district court judge in Billings, MT, upheld state water quality standards that had been challenged by coalbed methane producers. Conservation groups claimed "a major legal victory" while at least one producer said it was in compliance and no changes to operations would be necessary (see NGI, Oct. 29, 2007).

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