There is no question that California’s water system is in crisis. With water levels at their lowest point in decades, there are increasing concerns that our state’s water supply and delivery system may not be able to meet growing needs.1  California’s current drought has greatly increased water competition in areas with oil and gas wells, 96% of which are located in areas  experiencing severe water shortages.2

Given the significance of securing California’s water supply, it is important to understand the potential consequences of fracking and other forms of unconventional oil development on California’s water supply including availability and price of water, the potential for water contamination, and the billions of barrels of contaminated water that are produced as a byproduct of the fracking process.

Water use during the fracking process. (Source: U.S. EPA)

Water use during a horizontal fracking process. (Source: U.S. EPA)

Access to Water

Development of shale energy resources requires a large amount of water, with estimates ranging between two to nine million gallons per well.  However, there is a lack of clarity about how much water is used to frack in California. According to voluntary oil-industry data supplied to the Department of Oil, Gas, and Geothermic Resources (DOGGR), the average fracked well in California used 166,714 gallons of water in 2012.3

Although total water use for hydraulic fracturing is a relatively small amount when compared to a state’s overall water use, this increased demand for water can have dramatic effects at the local level.  Almost half of U.S. shale oil and gas wells are in regions with high to extremely high water stress.4 Furthermore, according to DOGGR officials, only 5% of the water used in fracking is treated and reused in non-industrial purposes. The rest is either injected into disposal wells or used in other oil extraction projects.5

Water tanks lined up at a fracking job. Source: Wikimedia Commons

Water tanks lined up at a fracking job. (Source: Wikimedia Commons)

Competition for water coupled with scarcity can also drive up the cost of this precious resource in local communities.  Given projections that there will be a sharp increase in production over the coming years – and the potentially intense nature of local water demands – there is growing concern about the impact new oil wells in California would have on accessibility to water.  If the Monterey Shale were to be developed in California, there could be up to 27,584 wells drilled, using over 220 billion gallons of fresh-water.6 This presents significant water management challenges and could put California at greater risk of water shortages.

Produced Water

Produced water comes from the process of lifting oil and gas from water-bearing formations.  As oil and gas are lifted to the surface, water comes out with it.7  In California, oil fields generate far more produced water than oil or gas and it’s not uncommon for an oilfield to be composed of 80-90% water. DOGGR reports that oil and gas wells in California produced 3,083,038,501 barrels of water in 2012-approximately 16 times more than the volume of oil that was produced.

Produced water can be very dangerous as it contains many natural contaminants from deep under ground, including total dissolved solids (e.g., salts, barium, strontium), organic pollutants (e.g., benzene, toluene) and normally occurring radioactive material such as Radium 226.8

The major components of produced water are:

  • Inorganic and organic chemicals: These chemicals are found naturally in the formation, are transferred to the water through long-term contact with the hydrocarbon, or are chemical additives used during drilling and operation of the well.  The presence of specific chemicals and the concentrations of those chemicals vary widely among different produced water samples.
  • Naturally occurring radioactive material (NORM): Some of the formations holding oil and gas have small concentrations of natural radioactivity.  Radioactivity can be transferred into produced water.
  • Salt content: Salt content can be expressed as salinity, total dissolved solids, or electrical conductivity.  The salt content in produced water varies widely, from nearly freshwater to salt levels up to ten times higher than seawater.
  • Oil and grease: The term “oil and grease” refers to a common test method that measures many types of organic chemicals that collectively lend an “oily” property to the water.

Wastewater Management

After fracking, some of the fracking fluid returns to the surface.  This wastewater, consisting of both flow-back and produced water, is extremely salinized and can be toxic. Hundreds of billions of gallons of wastewater are produced by the oil and gas industry each year.9  This massive amount of water needs somewhere to go and is usually managed in the following ways:

Evaporation ponds next to a typical fracking operation. Source:  Ted Wood/Corbis

Evaporation ponds next to a typical fracking operation. (Source: Ted Wood/Corbis)


Traditionally, wastewater was evaporated in pits and then the dry dregs were trucked to landfills or designated dumping sites.10   Evaporation of wastewater has raised concerns about air quality issues since contaminants contained within the produced water are evaporated into the air.11  Learn more about air quality issues.

Storage in Disposal Wells

Disposal wells serve as holding tanks for the produced water.  Storage of produced water in disposal wells has raised concerns that it runs the risk of leaking or overflowing, which can lead to groundwater and surface water pollution.  There have been cases where natural disasters have caused compromises to wastewater storage facilities.12

In 2013, flooding in Colorado inundated a main center of the state’s drilling industry causing over 37,380 gallons of oil to be spilled from ruptured pipelines and damaged storage tanks that were located in flood-prone areas.  There are serious concerns that the oil-laced floodwaters have permanently contaminated groundwater, soil and rivers.

This home was damaged by a magnitude 5.7 earthquake in Oklahoma.  An earthquake of that size is extremely rare in the region and scientists suspect the quake was triggered by nearby wastewater injection wells.

This home was damaged by a magnitude 5.7 earthquake in Oklahoma. An earthquake of that size is extremely rare in the region and scientists suspect the quake was triggered by nearby wastewater injection wells.

One of the biggest concerns about underground disposal wells is the seismic impact from wastewater injections into the earth.  Extensive research has been done on the connection between wastewater injections and earthquakes.  A recent analysis of geothermal wells located directly over the San Andreas Fault found that there was a linear relationship between the number of earthquakes and the net water production and injection rates.  For every 500 million gallons of water injected into the ground per month, there is an earthquake every 11 days, on average.13  Read more about produced water and earthquakes.

Re-use/Recycling of Wastewater

In order to be reused, produced water has to be treated extensively.  There are a number of methods to recycle drilling waste, but all are considerably more expensive then the alternative forms of wastewater management.  Some drillers have used recycling equipment at the well site or trucked the water to a recycling facility where the wastewater is filtered, evaporated, and then distilled and used again at the same well. Other companies add fresh water to the wastewater, to dilute the salts and other contaminants, before pumping it back in the ground for more fracking.14

Water Contamination

Due to the range and volume of activity necessary before, during and after the fracking process, water contamination associated with fracking is a major concern.  During the fracking process, fluid can cause surface and groundwater water pollution as a result of leaks, blowouts and other accidents.  Other major pathways of contamination occur during transport,  storage, or improper disposal or near fracking well sites.15

In 2012, a local farmer recorded video of oil company Vintage Productions illegally dumping fracking waste into an unlined pit.  In 2013, the company was fined $60,000 after an investigation by the Central Valley Regional Water Quality Control Board, the first time a state agency has penalized any company in relation to unconventional well stimulation.

Water contamination has been reported in more than 1,000 locations across the country.   Below are several studies that document the potential for water contamination caused by fracking in California and in other states.

Water Contamination Studies

Title Publication Authors Year Findings
Hydraulic Fracturing and Water Resources: Separating the Frack from the Fiction Pacific Institute Heather Cooley and Kristina Donnelly 2012 Found that Groundwater contamination from shale gas operations can occur through a variety of mechanisms including but not limited to well casing failures, abandoned well leaks, and natural underground fractures that leak into groundwater sources. 
Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction PNAS Robert Jackson et al. 2013 The study analyzed 141 drinking water wells across northeastern Pennsylvania, and detected methane in 82% of drinking water samples, with average concentrations six times higher for homes less than 1 km from natural gas wells.
Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing PNAS Stephen Osborn et al. 2011 The study found "systematic evidence for methane contamination" of drinking water associated with shale gas extraction." Water wells half a mile from drilling operations were contaminated by methane at 17 times the rate of those farther from gas developments.
Potential Contaminant Pathways from Hydraulically Fractured Shale to Aquifers National Ground Water Association Tom Meyers 2012 Found that natural faults and fractures in the Marcellus Shale, exacerbated by the effects of fracking itself, could allow fracking fluids and its chemicals to reach the surface in as little as "tens of years" — challenging the argument that impermeable layers of rock would keep fracking fluid, which contains benzene and other dangerous chemicals, safely locked nearly a mile below water supplies.
Regulation of Hydraulic Fracturing in California: A Wastewater And Water Quality Perspective Berkeley Wheeler Institute for Water Law and Policy Michael Kiparsky and Jayni Foley Hein 2013 Found that fracking could impact California water resources.  Contamination by oil and gas wastewater may pose risks to human health and environmental quality. The primary avenues for contamination most likely stem from activities at the drilling site such as mismanagement of produced water by dumping, leakage from storage areas, or spills. Contamination may also result from failure of well casing or cementing.
Venting and leaking of methane from shale gas development: response to Cathles et al. Climate Change Robert W. Howarth, Renee Santoro, Anthony Ingraffea 2012 The study looked at aging well sites and found that the percentage of methane leaks can increase to 30 or 50 per cent. The worst leaks are "deviated" or horizontal wells commonly used for hydraulic fracturing.
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