MCCOMB, Miss. (AP) — It takes between 6 million and 11 million gallons of water to frack an oil well in the Tuscaloosa Marine Shale formation of southwest Mississippi and central Louisiana.
Some two dozen wells have been fracked in Amite and Wilkinson counties since 2007, when TMS drilling got underway.
Oilfield watchers say those numbers could swell into the hundreds over the next few years and into the thousands beyond that.
Where will all the water come from?
And where will the contaminated wastewater go?
So far, oil companies have been using surface water such as ponds and streams.
Streams are state waters, and withdrawal requires permits from the Mississippi Department of Environmental Quality, said Richard Harrell, director of the Office of Pollution Control.
Taking water from a pond that is fed by "state waters," including a stream or a well, requires a permit as well.
"As the play gets closer and closer to a commercial status, we've told them (oil companies) we expect a long-term water plan: Where do you plan to get this water from, knowing the nature of the streams in that area," Harrell said, citing the small size of southwest Mississippi rivers like the Amite, Tangipahoa and Tickfaw.
If surface water proves to be insufficient, another alternative could include groundwater from non-drinking aquifers.
Drinking water aquifers range from 100 to 1,400 feet.
"Our intention is to not use that water for fracking," Harrell said. "At 2,000 feet are fairly sufficient quantities of groundwater that are suitable for fracking but are probably not suitable for drinking water.
"We're expecting them (oil companies) to come in with some plans for groundwater withdrawals. We feel that's a fairly copious amount of water that would have very little effect on people down there."
A third alternative involves impounding water when it's plentiful and finding alternative sources during dry times, such as piping it in from larger bodies of water.
"There's been discussions of taking the city of McComb's (wastewater) effluent or going over to the Mississippi River and taking water from that area," Harrell said.
A fourth option is recycling contaminated frackwater. To frack a well, water is mixed with sand and chemicals to hold open fractured layers of rock that contain oil and gas. Recycling the contaminated water is expensive, and returns from the TMS have yet to justify it.
Doug Hock, director of community and public relations for Encana oil company, said surface water is all that's on the horizon for the foreseeable future.
"Our intent would be to continue to use private ponds, and we've been using water from the Amite (River) east and west forks. Our preference would be to use pond water. We would not want to tap into the aquifer. We would avoid that at all cost," Hock said.
Hock suggested landowners might want to consider building ponds to sell the water.
"It's an economic opportunity for them," he said. "Unlike some of the areas where we operate, like Colorado, it's not arid."
Just any old pond won't do.
"A pond that's 20 or 30 acres has a lot of water, while a small pond for watering cattle isn't going to have the volume required for a frack," he said.
Gary Steen, U.S. Natural Resource Conservation Service soil conservationist for Amite and Wilkinson counties, said he doesn't know of anyone yet who has built a pond just as a source of fracking water. The agency advises landowners on topography, soil type and other issues.
"I won't say they're being built for that purpose," Steen said. "A lot of the ponds we have built have been used for that. We have had one or two landowners call in asking about pond sites in anticipation of them needing water (for fracking)."
He said pond construction costs roughly $5,000 to $7,000 per surface acre, depending on depth and site issues.
Earlier, oil companies were paying 35 cents per 42-gallon barrel of water, which translated into tens of thousands of dollars per frack. Now they reportedly pay an upfront fee plus a smaller amount per barrel.
Hock said oil companies will likely turn to recycling fracking wastewater once the play becomes commercial.
"It requires a certain volume where it makes sense economically and environmentally to recycle," he said. "If we reach a point where it's feasible to recycle, that is our preferred option."
Goodrich Petroleum spokesman Daniel Jenkins provided fewer details about his company's water plans.
"We are in the early stages of developing the Tuscaloosa Marine Shale oil play," Jenkins said in an email. "Since 2012, there have been approximately 30 wells drilled and completed within the core TMS development area. Goodrich Petroleum has worked with, and will continue to work with, state regulators to ensure that all water sourcing and water disposal operations will be in compliance with applicable rules and regulations."
Jenkins said it's hard to be more specific.
"We are drilling wells over a 6,000-square mile area from depths between 11,000 to 14,500 vertical feet deep. Lots of variability."
So where does the contaminated water go when fracking is finished?
That's the domain of the Mississippi Oil and Gas Board. David Snodgrass, geologist and environmental administrator, said wastewater is injected back underground into the oil formation, far below drinking water levels.
Amite County has 10 active injection wells, he said. A typical injection zone is 8,500 to 8,900 feet deep.
Saltwater, as oil well wastewater is often called, is also heavier than freshwater and not likely to migrate upward.
"We're very blessed in Mississippi to have the oil and the injection zones separated from drinking water by great depths," Snodgrass said. "That makes fracking a lot safer."
Oil and Gas Board, http://www.ogb.state.ms.us click on "Tuscaloosa Marine Shale."
Information from: Enterprise-Journal, http://www.enterprise-journal.com