Some oil and gas producers are going after that oil using a controversial extraction technique known as fracking. It involves blasting highly pressurized water, sand and chemicals down wells to fracture the tight rock formation and force natural gas and oil out.

Nationwide, fracking has sparked an at-times rabid debate about possible risks to drinking water. 
There are instances where fracking has contaminated groundwater, but how often it occurs and where is highly contested.

That fight could be coming to California.  While much of the fracking boom elsewhere has been about natural gas-- in California, it's about oil.

Because of the growing national controversy over fracking, the industry doesn't want to talk about where and how much it's using the technique in California.

But other states are further along in the discussion -- and regulation -- of fracking and protecting groundwater.  Take the arid state of Colorado.

Dave Neslin was head of Colorado Oil and Gas Conservation Commission when the state pushed through new rules governing fracking.  He says a number of the rules are designed to prevent water contamination, because it has happened in Colorado.

"In specific circumstances, where the casing or cementing of well has failed,  that has happened, there've been instances where groundwater has been contaminated, or more frequently where waste pits have leaked-- that's led to contamination," Neslin says. 

"And when that happens we require operators to remediate those areas, and we've assessed penalties where that's appropriate.  And we've required operators to provide nearby residents with replacement water."

Still, some residents are worried we don't know enough about the impact of fracking on the environment.

Living With Fracking

Jen Palazzolo is one of four moms spearheading the activist group Erie Rising, which is demanding more information about fracking.  She lives in Eric, Colo., a small but growing town north of Denver.  Just east of the Rocky Mountains, it's full of sprawling subdivisions, bike paths, and schools-- and it sits in a county with more than 18,000 active fracking wells.

Palazzolo drives me to a well that was recently drilled next to her daughter's elementary school.  The rig is no longer up, and the drilling area is surrounded by a ring of a makeshift metal walls with haybales, to keep the noise down for the subdivision next door.

"As a parent I just feel very violated, that I live in this community, I do everything I can to keep my children healthy, you know you buy plastic without BPA, you buy organic food-- and then you send them to school and 600 yards away, you have this huge industrial operation, and you have very little disclosure as to what's going on," Palazzolo says.

The well has since been fracked, and now will be producing for the next few decades. Palazzo says she's really worried about the kids' safety -- there will be hundreds of truck trips driving near the playground and the organic garden.
 
"For the life of the well, you'll always have them picking up the product, they'll pick up the produced water, which is full of toxic chemicals, so what is the risk accident or a spill right in front of the school? What would that mean? "

Palazzolo is busy juggling her part-time job as a pharmacist, taking care of two kids, and now she's become a part-time activist.  She drives me around the town pointing out active wells hundreds of feet from churches, homes, and parks.

"I would say, if you added up all the well heads, there are probably 30 or more wellheads in one-mile radius of the high school."

After a well is fracked, which usually takes a day or two, the remaining wellhead is quite small. The footprint of the whole operation might be about the size of a few parking spots.  Over the several decades of the life of the well, it will continue to produce natural gas, and wastewater will also come back up the well.  Both are collected on site in non-descript tanks.

Palazzolo says before she knew about fracking, she always assumed these ubiquitous tanks in fields and behind the shopping mall were just holding water or fertilizer for agriculture.  Now that she know they are active wells, she says she can't think about her town the same way.

Palazzolo wants more answers about how the industry handles wastewater, and its plans for responding to a spill. She says she doesn't feel better after attending a number of public meetings the industry has held in town.

"That's the problem, (the industry) seems to put information out there that its okay, with no scientific data, research, numbers to back it up. "  

Looking for Answers

The lingering question is -- does fracking actually pose a risk to groundwater ?

Geologist Geoff Thyne says there's an inexpensive, easy way to tell:
 
"We put a tracer in the frack fluids. Tracers are widely use throughout industry… so there's no particularly onerous expense, there's no new knowledge-- and this protects the producers."

Putting a chemical marker, or tracer, in the frack fluid would protect the producers, Thyne says, because then they could unambiguously prove if water contamination came from frack fluids or from naturally-occurring underground chemicals common in areas with plentiful oil and gas. 

This method is now being tested in Pennsylvania.  A drilling company there is working with the Department of Energy to do a study by putting tracers in frack fluid.

 
Thyne has worked in the oil and gas industry, for public universities and sits on an EPA advisory board studying fracking.  He thinks fracking can be a useful extraction method with proper safeguards. 

But he's lost two different jobs for his outspoken opinion that more study is needed.

"We're not providing the public with the tools they need to have confidence in our activity," Thyne says.  "When you keep going 'oh, don't worry, we've got it under control, we did closed loop.' Well that's great. Do you have any data?  Will you share that data with us?"

But the industry says it's already doing enough to protect drinking water.  Over at a well pad in Erie, Colo., Wes Harrison with Encana Corporation shows me the many precautions the industry takes to protect groundwater. 

Speaking above the thrum of the iron roughneck that's mechanically feeding the thick metal casing down the wellbore, he explains the importance of the more than 850 feet of casing:

"We run this casing, and then we cement it, and that protects any aquifers from any hydrocarbons trying to come up the hole," says Harrison. 

The mix of frack chemicals and water that is injected into the well gets a lot of attention in the press,  but when the water comes back up the well it contains even more chemicals.  That's because it also has picked up natural chemicals and salts and sometimes radioactive elements from the deep underground rock layers.

That's why the cement seal around the well pipe is crucial. 

It's rare, but as Doug Hock with Encana explains, cement casing failures can happen.  He says Encana had a contamination incident on Colorado's west slope, back in 2004.

"The cement that was going down around the casing failed, and we didn't realize it," says Hock.

They drilled into a pocket of naturally-occurring benzene, he says, which then came up the wellbore and went into a creek.  Encana paid a roughly $370,000 fine.

Colorado learned from this failure, and changed its rules. The state now requires testing the cement integrity before companies can start fracking.

Fracking in California

Back in California, fracking efforts have been largely under the radar of the state.  California doesn't track fracking at all; it doesn't know how many wells are being fracked, where they are, or how much water they're using. 

When wells are constructed properly, the overall the risk of water contamination is low, says geologist Jan Gillespie, a professor at CSU Bakersfield who has worked for the oil industry.  And she says much of the water table in the Central Valley is protected from contamination by thick layers of clay.

But she does have some concerns about fracking in the Monterey formation: 

"I think what I've always worried the most about is probably the integrity of old well bores," says Gillespie.

The San Joaquin valley is full of old abandoned wells. Gillespie says decades ago there was no requirement to officially seal the well and industry left many uncapped.  And if you start fracking in the middle of all this:
 
"And if you're sending out a high pressure fluid, could it enter a poorly abandoned well and move up an old well bore into something  else?"

The central valley is full of these holes, says Gilllespie, that could become pathways for nasty water full of oil and other natural chemicals to move into other parts of the soil.  While much of the water in Kern County is not drinking quality, she says there are places where the drinking water aquifers are vulnerable, and would have to be carefully protected.

A Recipe for Earthquakes?

And another concern of injecting highly-pressurized water into California's rock formations is the possibility of earthquakes.
 
Stanford University geology professor Mark Zoback says fracking may trigger some tiny, "microseismic" earthquakes that are barely detectable to seismologists.  But he says the risk of fracking triggering a dangerous earthquake is essentially negligible. Disposing of frack water, on the other hand:

"Now when you start injecting larger volumes for longer periods of time, such as in a disposal well, there is a risk. And the sites have to be located in places with the appropriate geology."

Zoback says in some cases industry should also set up a seismic network to monitor if injections are changing activity. 

The oil industry has been using these kinds disposal wells for decades;  California has over 25,000 injection wells, which are regulated by the state and fall under EPA guidelines.  

And as industry will attest, fracking in California isn't new either.  But now companies are using the controversial technique to go after deep shale rock.  And they're trying multi-stage fracking, which involves injecting multiple rounds of water.  Some companies are also doing horizontal drilling and fracking, which means drilling down into the shale formation, then turning the wellbore sideways and drilling into the shale horizontally. 

Given the public uproar about fracking across the nation, and the increasing attention to it in California, the state has started writing rules to govern fracking.  A draft could be available for public comment sometime in the next few months. 

But the rulemaking process could take a while. And if oil prices go up, fracking in California could become even more profitable.  That might mean an escalation of the fight that's already flaring in other corners of the country.