Care is needed to protect McPhee Dam if a proposed oil-and-gas lease is developed nearby, according to Montezuma County commissioners.
In a comment letter to the Bureau of Land Management, the commissioners stated that they supported oil-and-gas development, but they expressed concerns about potential geologic hazards on proposed lease Parcel 7393 west of McPhee Reservoir.
“The BLM should analyze the impacts the proposed lease sale would have on the operation and integrity of the McPhee Dam,” the Aug. 31 letter stated.
“Since the proposed lease sale will occur within ¾ of a mile from the dam, we believe that the potential for seismic activity due to drilling should be thoroughly evaluated.”
The proposed lease pertains to a split estate where the surface is privately owned, and federally owned subsurface minerals are leased to energy companies.
A U.S. Geological Survey map of fault lines in the area does not show one near the McPhee dam or parcel 7393.
However, the lake itself sits on a fault line that runs under House Creek, under a portion of the reservoir, and under the dam for Narraguinnep Reservoir.
“The weight of the lake on top of the fault could be an earthquake risk,” said James Dietrich, federal lands coordinator for the county.
Local resident Ellen Foster recently pointed out the proximity of the proposed lease to the dam to county staff, and those concerns were added into the county comment letter.
“Drilling so close to the dam is too risky and threatens our entire economy,” she said.
Horizontal drilling can travel for up to two miles from the wellhead. But if the lease were sold and wells were drilled, the company could not drill outside the unit boundary, Dietrich said.
Whether the practice of hydraulic fracturing, or fracking, will be used at the parcel near the dam will not be known until the parcel is leased for development and an drill application is submitted to the BLM.
Fracking is the process of injecting wells with up to millions of gallons of water, sand and chemicals at very high pressure. The process creates fractures in deeply buried rocks to allow the flow of oil and gas into the well bore.
The USGS says fracking has rarely created earthquakes, but USGS scientists have linked underground injection wells – used to dispose water produced from drilling – to more common minor quakes.
The injected fluids are salt water left over from ancient seas that is drawn up during drilling. When injected back underground 6,000 to 8,000 feet deep, it can lubricate unstable fault lines and trigger earthquakes.
According to a county map, three injection wells in the western part of the county are used by the local oil-and-gas industry, including the Kinder Morgan CO2 Co. Well MWD is on Road 18, north of County Road T; Well HWD-1 is at County Roads AA and 12; and Well YWD-1 is in the Yellow Jacket area in between Roads X and Y. Whether they are near fault lines is unknown.
Oil-and-gas development within the county requires a High Impact Permit and Special Use Permit which will further evaluate site specific conditions, and may impose additional mitigation measures.
