Montana’s Regional Ground – Water Monitoring Program in the Powder River Basin Montana Bureau of Mines and Geology

Coalbed methane production water by month. Note scale changes on each graph.

Montana Wyoming North Dakota South Dakota Powder Casper Miles City Forsyth Belle Fourche River North Platte River Tongue Yellowstone River Very simplistic : Ground water flows Generally north

Montana Wyoming North Dakota South Dakota Powder Casper Miles City Forsyth Belle Fourche River North Platte River Tongue Yellowstone River 1 Montana 1/3 of PRB 10% of gas Wyoming 2/3 of PRB 90% of gas

South North Powder River Basin, Montana Cross Section 1 South to North Wyoming Montana Yellowstone River Tongue River Member Lebo Member CBM Ground – Water Flow

Lebo Shale Member CDEHJCDEHJ I F G Hanging Woman Creek Powder River Tongue River Coal beds identified in cross section A Roland B Smith C Anderson D Dietz E Canyon F Carney Coal G Wall Coal H Knobloch I Roberts Coal J Kendrick ABAB Cross section along the Montana – Wyoming state line

Montana Wyoming

Figure 20. Water levels in the combined Anderson and Dietz coal (WR-34) in the Squirrel Creek area respond to both coal mining and coalbed methane production. The water level recovered starting in 2004 in response to water production decreases in this portion of the CX field. Ash Creek Mine begins dewatering Reclamation began Reduced water pumping rates in western parts of CX field

Stratigraphic relationships Ground surface Shallow sandstone Anderson-Dietz overburden Anderson-Dietz Coal Altitude (feet amsl)

Water Level Altitude (ft-amsl) Stratigraphic relationships Ground surface Shallow Sandstone Wall Coal overburden Wall Coal Altitude (feet amsl)

Water Level Altitude (ft-amsl) Stratigraphic relationships Ground surface Sandstone Smith Coal Anderson Coal Canyon Coal Altitude (feet amsl)

Stratigraphic relationships Ground surface Smith Coal Anderson Coal Altitude (feet amsl)

Canyon Coal

Water / Gas Ratio varies considerably with time and well Area of Drawdown Extends 1 to 2 miles outside CBM Production Fields Recovery begins when CBM wells stop pumping Little vertical migration of drawdown