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2003
RIVER
RESCUERS
UM'S NEW RIVERINE SCIENCE CENTER
POISONED
HEARTS
ARSENIC EFFECTS ON CARDIOVASCULAR HEALTH
WATER
WIZARDRY
BIO STATION'S NEW FLOOD PLAIN MODEL
RIVERS
THAT TIME FORGOT
AN UNDISTURBED RUSSIAN WILDERNESS
SODIUM
SOLUTIONS
COALBED METHANE IN EASTERN MONTANA
HEAVY
METAL
SCIENTISTS STUDY IMPACT OF METALS ON MICROBES
COTTONWOOD
CONUNDRUM
MONTANA'S DISAPPEARING RIVER TREES
WATER
WARDENS
UM'S WATERSHED HEALTH CLINIC
TALLYING
TADPOLES
STUDYING MONTANA AMPHIBIANS
FISH
FINDERS
DNA IN WATER REVEALS LOCATION OF FISH
WET
AND WILD
A PRIMER ON MONTANA AQUATIC LIFE
WATER
THAT WAS
THE SECRETS OF GLACIAL LAKE MISSOULA
NEWS
TO USE
THE WEIRD LIFE CYCLE OF SWIMMER'S ITCH
BACKTALK
GIARDIA: A WATER DRINKER'S GUT-WRENCHING SURPRISE
Coalbed methane challenges eastern Montana rivers
By CARY SHIMEK
Ranchers in the Powder River Basin of southeastern Montana have long known their drinking water sometimes comes with a kick.
In fact, an unwary ranch hand who lights a match in the well house might accidentally blow the place sky high.
That's because domestic water wells in the area often tap into coal seams a few hundred to more than 1,000 feet deep. The water can be good quality — it has its own natural charcoal filter — but sometimes natural methane gas trapped in the coal seam comes up the pipe as well, which can create an explosive surprise.
New technology now makes it profitable for developers to go after the gas, which could mean big changes for the Powder and Tongue rivers, two of eastern Montana's most important waterways.
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| Professor Richard Hauer |
Professor Richard Hauer of UM's Flathead Lake Biological Station is an expert on lakes, wetlands and streams. He and station director Jack Stanford were asked by the state Legislature to provide an independent academic review of coalbed methane production on water quality and the river ecosystems that may be affected in eastern Montana.
"This is about as complex an issue as you could possibly find," Hauer says. "It's very dry in that area and water is a very precious resource. Water quality, fish, wildlife and other aquatic life of the rivers, plus the farmers who irrigate from the Tongue and Powder rivers, may all be affected by coalbed methane development and production. There are many things that we are uncertain about in all this. I certainly would tread very carefully out there."
According to a draft Environmental Impact Statement, about 20,000 wells would be needed to bring the Powder River Basin coal seams to full development, and production would then last about 30 years before the resource was depleted. Right now the only coalbed methane wells in Montana are concentrated near Decker, on the Tongue River close to the Wyoming border.
Coalbed
methane fields generally contain a high density of wells — about
three to five every 80 acres. The surface disruption includes a
network of roads, well pads, pipelines,
concentration stations and disposal ponds.
"We found the number of roads and other surface disturbances associated with development, such as the pipelines, rather disturbing," Hauer says. "It has been documented time and time again that large-scale disturbance to surface soils often results in modifications to water quality as it flows through and out a basin."
But the biggest conundrum is what to do with all the water produced by coalbed methane production. The water, typically high in sodium and other dissolved solids, is pumped out of the ground in order to release the trapped methane gas. Each well produces about 2.5 to 10 gallons of water per minute, which translates to about 110 to 450 cubic feet per second if the basin is brought to full production. It's a lot of water that has to go somewhere.
In Wyoming, which already is charging ahead with coalbed methane development in the basin, waste water generally is discharged directly into the Tongue and Powder rivers, which then flow north into Montana. This, however, might not be a good solution for water disposal in Montana. Based on the data, it appears that water coming from the coal-seams in Montana tends to be saltier than water in Wyoming. Hauer says that direct discharge of the higher sodium concentration coal-seam water in Montana could adversely affect the chemistry and biology of these rivers.
Stanford and Hauer's white paper specifically focused on the implications of development on water quality and river ecology. They evaluated several potential solutions to coal-seam water disposal with varying levels of risk and uncertainty. They reported that the least risky solution would be to re-inject the water back where it came from, but Hauer says most industry officials tell him that would be prohibitively expensive.
Another potential solution is holding ponds that allow the water to evaporate or drain back into the ground. But Hauer says evaporated coal-bed water would leave a salted hardpan on the bottom of the ponds after the gas is depleted and production stops. A better option would be lined ponds, but once again these are expensive.
Other options include using the water for livestock, but cattle couldn't keep up with the volume they would be faced with. Or it could be used for irrigation, but there are limits to the amount of sodium water that can be applied to fields without permanently damaging them.
Hauer says direct discharge of coalbed methane water into the Tongue and Powder rivers carries the greatest uncertainties. The practice could change the rivers' chemistry to sufficient extent that use by native river species would be compromised and irrigated farmland could be impaired.
Eastern Montana is dry, and life clusters around the rivers there. One might assume that more water would be good, but he says that's not always the case.
"The ecosystem there may be very dependent on periodic drought. Native species may maintain their competitive edge against non-native species that might move in without drought," he says. "If we change that environment by adding more water, then you may select for organisms other than the ones that occur there as natives."
He says a "one-size-fits-all" method for dealing with the coal-seam water — while that may be easiest to legislate and regulate — may not be appropriate for Montana's Powder River Basin. He says the type of water produced from the coalbeds changes across the landscape, so if there is development, administration of the gas fields should vary between locations. Detailed water chemistries from each well should dictate the regulation and disposal of the water.
Hauer says eastern Montana could see an economic windfall from coalbed methane development. However, he adds that in Montana's past there have been various kinds of resource extraction with long-term ecological and sometimes human-health ramifications.
"Clearly, Montanans should want to be cautious about repeating past mistakes," he says. "Rushing into things oftentimes results in something you are really sorry for later."
Related links: Hauer and Stanford's paper.