Toxic Stew

What’s in Fracking Wastewater

March 10, 2015

Toxic Stew: Full Report

California responds to a national problem

In hydraulic fracturing,or “fracking,” large volumes of water are mixed with relatively smaller amounts of chemicals and sand, producing a thick slurry known as frack fluid. In other states, hundreds of thousands gallons (up to 20 million in some cases) are used in each well, but the oil and gas industry says wells drilled in California’s unique geology typically require no more than 130,000-210,000 gallons apiece (CCST, 2015). The fluid, pumped deep underground under high pressure, fractures shale rock formations to free up trapped oil and gas. A closely related process, acid stimulation, involves pumping water laced with chlorine and/or fluorine acids, sometimes in concentrations strong enough to actually dissolve oil-bearing shale, under relatively lower pressures. Collectively the two techniques are called well stimulation.

After a well is fracked, much of the fluid returns to the surface – anywhere from 15-to-80 percent, according to the U.S. Environmental Protection Agency (EPA, 2010). This wastewater includes flowback from the chemical-laced fluid that was pumped in and formation water that occurs naturally in the shale and is brought back to the surface with the oil or gas. The industry’s term for both types of waste is produced water.

Drilling a well produces much more wastewater than oil. Nationally, a typical well yields an average of 7.6 barrels of water for each barrel of oil. California is second only to Texas in the amount of produced water generated from total oil and gas activity (ANL, 2009). In 2013, the state’s oil and gas industry produced more than 130 billion gallons of wastewater (USGS, 2014).

All that wastewater has to go somewhere. Some is stored in surface reservoirs, where it either evaporates or percolates into the ground (CWA, 2014). Some can be immediately re-injected into the ground to help force more oil to the surface, a process known as water flooding. A smaller portion is heated to make steam and injected to soften heavy oil deposits. However, the wastewater cannot be recycled this way if the water quality is low, and because of the high cost and technological challenge of removing the toxic chemicals, most of it is injected underground into aquifers whose water is deemed by the U.S. EPA to be unfit for drinking or agricultural use. California has more than 50,000 injection wells for disposal of oil and gas wastewater (Bohlen and Bishop, 2015). Nationwide, there are more than such 170,000 wells (GAO, 2014).

Injection for disposal is legal only in poor-quality aquifers, but contamination may occur when injected fluids migrate into an area with high quality water. This can happen as a result of weak regulation of injection procedures, faulty well construction or poorly executed well abandonment.

The danger that chemicals in fracking fluid and produced wastewater could contaminate drinking and irrigation water supplies has caused widespread concern across the country among citizens and regulators, who have pressured the industry to disclose the chemicals it uses.

In the absence of a national disclosure law, a number of states now require drillers to report to the website (, 2015), and some drillers voluntarily do so. But FracFocus is partly funded by the oil and gas industry, and the reporting may be less than transparent (Hass et al, 2012). Moreover, FracFocus makes public the information submitted by drillers without checking for accuracy or completeness. Drillers can withhold details about the chemicals they use by claiming that their formulas are trade secrets. FracFocus does not provide for or require drillers to test wastewater and report the results.

California’s new disclosure requirements closes many of the loopholes in FracFocus. In 2013, legislators passed and Gov. Jerry Brown signed Senate Bill 4, the state’s first law regulating fracking (Senate Bill 4, 2013 - Some of its provisions will not be fully implemented until June 2015, but disclosure under interim regulations went into effect on Jan. 1, 2014, and some records on the state website are for wells fracked as far back as December 2013.

The law’s disclosure requirements are far-reaching and in some cases unique to California. Before a well is fracked or undergoes acid stimulation, drillers must submit a notice that includes the names and concentrations of all chemicals and other substances to be used. The Division of Oil, Gas and Geothermal Resources maintains an online searchable database [] of this information (DOGGR, 2015). Property owners near the site must get a copy of the notice at least 30 days before fracking begins, and landowners may request water sampling and testing, paid for by the driller, of any drinking water or irrigation well on their property.

Through early January 2015, a total of 1,314 notices had been posted – 1,249 for fracking and 65 for acid stimulation (Table 1). Although fracking has been used in at least nine California counties (CCST, 2015), almost all of the activity reported for 2014 (1,306 notices) was in Kern County. More than 80 percent of the notices came from a single company, Aera Energy LLC of Bakersfield, which is jointly owned by Shell and ExxonMobil.

Within 60 days of fracking the well, the driller must also disclose the source, volume and complete chemical composition of all fluid used. The information must also include the amount of wastewater recovered and how the driller disposed of it. The results are compiled in large and unwieldy spreadsheets, the Well Stimulations Disclosure Report [, posted on the Division’s website (DOGGR, 2015). According to the report, the well treatments recorded for 2014 used from about 12,000 to 226,000 gallons of water as base fluid.

Drilling companies must also sample the recovered wastewater, test it using state-specified methods and disclose the chemicals detected and their amounts. They must also measure other characteristics such as radioactivity. Detailed reports of each chemical test must be reported.


Table 1. California well treatment notices and wastewater testing reports, 2014

Operator Treatment notices by county
Wastewater testing reports
Kern Ventura Fresno Kings
Aera Energy LLC 1,071 3     460
Occidental of Elk Hills Inc. 133       53
Breitburn Operating LP 50       25
Vintage Production California LLC 36       12
Chevron USA 10       7
Seneca Resources Corp. 2   2   1
Central Resources Inc. 3       1
KMD Operating Co. LLC       2  
Crimson Resource Management Corp. 1        
DCOR LLC   1      
Totals 1306 4 2 2 559

Source: Environmental Working Group, from data reported to DOGGR up to January 5, 2015