BOARD01179

• Board Meeting Date: 7/25/2006
• Description: CWCB Director's Report
• Board Meetings - Doc Type: Memo

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Arkansas River Basin

Arkansas River Compact Administration (ARCA): On June 25 and 26 Hal Simpson and Rod
Kuharich met with David Pope as the ARCA Special Engineering Committee created at the Dec.
2005 Annual Meeting. Staff from both states presented the factual and policy basis for the
numerous contested accounting issues that Kansas has complained about under the 1980
Operating Plan for John Martin Reservoir. We neared agreement on several issues and developed
pathways to lead to resolution on several others. There are still large differences in how the
States view some provisions of the 1980 Plan. In recognition of the potential for litigation on
some of these issues the States agreed to keep the substance of their discussions confidential. We
will be meeting again in Topeka on Aug. 28-30.

Kansas v Colorado Litigation Account Update: A description of activities and summary of
expenditures for this project is included in the non-reimbursable memo contained elsewhere in
this report. As of June 30, 2006 we had expended approximately $500,000 of the $750,000
budget, with all work scheduled to be completed by June 30, 2007.

Las Animas County Groundwater Study: The USGS has released and posted on its website (
http://pubs.usgs.gov/sir/2006/5109/)astudyentitled: "A Preliminary Evaluation of Vertical
Separation between Production Intervals of Coal bed-Methane Wells and Water-Supply Wells in
the Raton Basin, Huerfano and Las Animas Counties, Colorado, 1999-2004." (SIR 2006-5109).

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The report abstract states: The Raton Basin in southern Colorado and northern New Mexico is
undergoing increased development of its coalbed-methane resources. Annual production of
methane from coalbeds in the Raton Basin in Huerfano and Las Animas Counties, Colorado,
increased from about 28,000,000 thousand cubic feet from 478 wells to about 80,000,000
thousand cubic feet from 1,543 wells, during 1999-2004. Annual ground-water withdrawals for
coalbed-methane production increased from about 1.45 billion gallons from 480 wells to about
3.64 billion gallons from 1,568 wells, during 1999-2004. Where the coalbeds are deeply buried
near the center of the Raton Basin, water pressure may be reduced as much as 250 to 300 pounds
per square inch to produce the methane from the coalbeds, which is equivalent to a 577. to 692-
foot lowering of water level. In 2001, the U.S. Geological Survey, in cooperation with the
Colorado Water Conservation Board, began an evaluation of the potential effects of coalbed-
methane production on the availability and sustainability of ground-water resources.

In 2003, there were an estimated 1,370 water-supply wells in the Raton Basin in Colorado, and
about 90 percent of these water-supply wells were less than 450 feet deep. The tops of the
production (perforated) interval of 90 percent of the coal bed-methane wells in the Raton Basin
(for which data were available) are deeper than about 675 feet. The potential for interference of
coalbed-methane wells with nearby water-supply wells likely is limited because in most areas
their respective production intervals are separated by more than a hundred to a few thousand feet
of rock. The estimated vertical separation between production intervals of coalbed-methane and
water-supply wells is less than 100 feet in an area about I to 6 miles west and southwest of
Trinidad Lake and a few other isolated areas. It is assumed that in areas with less than 100 feet of
vertical separation, production by coalbed-methane wells has a greater potential for interfering
with nearby water-supply wells. More detailed geologic and hydrologic information is needed in
these areas to quantifY the potential effects of coalbed-methane production on water levels and
the availability and sustainability of ground-water resources.

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The Board funded approximately 70% of the cost of the study. In FY2007 the Colorado Geologic
Survey, in cooperation with DWR, will be conducting a separate study to assess the tributariness

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