Shallow Fracking Near Water Supplies Must Also Be Stopped

Prepared by the Center for Biological Diversity for Californians Against Fracking

Download a PDF of the analysis here >> CCST White Paper Analysis


Two years ago, amid calls from scientists, health professionals, and the public to ban fracking, Governor Jerry Brown pleaded with Californians to “give science a chance before deciding on a ban on fracking.” Instead of prohibiting the hazardous practice, which blasts water and toxic chemicals underground at high pressures to crack rocks and release oil and gas, Governor Brown pushed forward with fracking, issuing permits for thousands of fracking operations across the state.

Now, the science is in: A major new report from the California Council on Science and Technology shows the clear dangers of fracking in California, including risks to public health and safety and the environment. Among the many recommendations in the scientists’ report, the panel called for an end to dangerous shallow-depth fracking and open waste disposal pits that contaminate water supplies.

Scientists also warned that California must institute a setback requirement to stop all oil and gas well drilling and production near homes, schools and other places where people are at risk from the harmful air pollution.


In September 2013, the State Legislature passed Senate Bill 4 (SB 4), which Governor Brown signed into law. SB 4 called for an independent scientific study on the environmental effects of fracking and other well stimulation techniques to be completed by January 1, 2015. The Natural Resources Agency retained the California Council on Science and Technology (CCST) to conduct the study.

However, the science panel completed only the first volume of its study, An Independent Scientific Assessment of Well Stimulation in California (the report), by the statutory deadline. The first volume only described well stimulation activity in California and provided no information about the risks to health and the environment.

On July 9, 2015, more than six months after the statutory deadline, the CCST released Volumes II and III of the report, which evaluate the potential environmental impacts of hydraulic fracturing (fracking) and acid stimulations in the state. After reviewing hundreds of peer-reviewed studies, CCST experts explained just how dangerous fracking in California is. The risks include substantial harm to air and water quality, public health, marine ecosystems, and the potential for inducing earthquakes.

In fact, the report cautions that fracking in California may be even more dangerous than in other states because wells in California are much closer to densely populated areas, active faults, older wells, and groundwater.

In light of the serious risks of fracking in California, the CCST recommends that all oil and gas wells be prohibited near places people may be exposed to toxic chemicals and recommends that no permits be issued for shallow fracking near protected groundwater.


Risks to Water

The report identifies a number of ways in which fracking can cause water contamination. Fracking in California’s unique geology potentially creates a greater risk to groundwater than elsewhere in the country.

First, the majority of fracking in California, roughly 75 percent, occurs at very shallow depths, mostly within 1,000 feet of the surface. In many areas, this means fracking is taking place at the same depths as groundwater. Moreover, because California has many older and sometimes undocumented oil and gas wells, there is potential for older wells to act as conduits and allow chemicals to migrate to sources of groundwater.

The science panel also states that groundwater monitoring “does not ensure protection of water, nor will it necessarily detect contamination should it occur,” and concludes that groundwater monitoring “does nothing to stop contamination from occurring in any case.”

The report calls for an end to fracking at shallow depths near groundwater unless operators can confirm that groundwater will not be contaminated. Such assurance would be difficult if not impossible to demonstrate given that California’s regulators have already admitted to widespread violations of federal law leading to groundwater contamination by the oil industry.

California has also allowed operators to dispose of wastewater, which contains a toxic mix of fracking fluid and naturally occurring chemicals, into unlined pits. The use of disposal pits allows chemicals to escape into the air, threatening nearby communities, and to percolate into the soil beneath, potentially migrating to nearby surface water or groundwater. The report confirms that the use of percolation pits has resulted in water contamination in California.

Given the danger of these pits, the CCST recommends that the use of percolation pits be phased out unless it can be shown that hazardous materials are not a part of the discharged wastewater.

Risks to Human Health

There are no state regulations that restrict where a well may be drilled. Thus, in many parts of the state, active wells are located only a few feet from homes, schools, daycare facilities, churches or other places people are exposed to the air pollution from the wells.

The report sets forth established scientific evidence that the closer a population is to active oil and gas development, the more elevated the risk to that population. Exposure to toxic airborne chemicals can occur up to 2 miles from an active well, and people living within a half mile from an active well are at significantly higher risk of getting sick.

In California, there are many densely populated areas near or even on top of active oil fields, increasing the risk of exposure to the population. According to the report, “Approximately half a million people live within one mile of a stimulated well, and many more live near oil and gas development of any type.” In the Los Angeles basin alone, about 1.7 million people live, and hundreds of schools, elderly facilities, and daycare facilities are located, within one mile of an active oil and gas well. More than 32,000 people live within 100 meters (328 feet) of such a well.

Some dangerous chemicals—like benzene, a carcinogen—are common to both fracked and conventional wells. The report emphasizes the need for a science-based minimum setback distance between oil and gas wells and homes, schools, hospitals, and other places where people could be exposed to the harmful chemicals used in oil and gas production.

The report also stresses a disturbing fact:

“[T]he scientific literature is clear that certain sensitive and vulnerable populations (e.g., children, asthmatics, those with pre-existing cardiovascular or respiratory conditions, and populations already exposed to elevated air pollution) are more susceptible to health effects from exposures to environmental pollutants known to be associated with oil and gas development.”

Although fracking presents unique risks because of the number of toxic chemicals used in the process, the report recommends that the setback apply to all oil and gas wells because of the danger posed by other stages of the production process such as drilling, well completion, and production. It notes that “the scientific literature supports the recommendation for setbacks.”

The report concludes that the unlimited use of toxic chemicals presents a risk to human health that is “directly attributable” to fracking. Dozens of chemicals used in fracking and other well stimulation operations in California are known to have adverse human health effects.

Other chemicals are either unknown or have not been adequately studied to determine how significant a risk to human health they pose. More than 100 chemicals have not been properly identified by well operators, even though complete disclosure is required under state law.

Two of the 20 most frequently used fracking chemicals have not been properly identified. There is little or no information on the toxicity of more than half of the chemicals used in fracking. The report also warns that there are no studies on the health effects of chemicals when used in combination, or after they have reacted with each other or with chemicals found naturally underground, or what types of sublethal effects they may cause.

In light of the substantial gaps in knowledge, the science panel recommends that the state limit the use of hazardous and poorly understood chemicals.

Air Pollution

The report warns that there is very little information in California regarding emissions from fracking, making it impossible to discern how much well stimulation is contributing to air pollution. For example, there are no studies in California tracking how much of the extremely toxic chemicals used in fracking and other types of well stimulation escape into the air.

The lack of data on where chemicals involved in well stimulation and other stages of oil production travel is also a cause for concern because of their toxicity. The report notes that compounds “of particular concern that are known to be emitted during well-stimulation-enabled oil and gas development” include benzene, toluene, ethylbenzene, xylenes, formaldehyde, hydrogen sulfide, particulate matter, nitrogen oxides, sulfur dioxide, polycyclic aromatic, aliphatic, and aromatic hydrocarbons and volatile organic compounds.

The closer people are to oil and gas activities, the report emphasizes, the higher their potential exposure to toxic air emissions and the higher the risk of associated health effects. The harmful emissions “could present health hazards to nearby communities in California.”

Existing emissions data do not distinguish between pollution from well stimulation and that from other stages of oil and gas production. However, the oil and gas industry in the San Joaquin Valley, largely enabled today by fracking, is responsible for more than 30 percent of man-made, regional sulfur dioxide emissions and 70 percent of hydrogen sulfide emissions.

Given the lack of data on air emissions, the CCST recommends that the State measure the toxicity of the air near active wells and restrict the types and quantities of air toxics that may be used.

Seismic Hazards

Fracking and the injection of wastewater produced from fracking and similar processes have the potential to cause earthquakes in California, as they already have in other states.

Two factors contribute to the potential for induced seismic activity to be “at least as high in California” as elsewhere in the country.

First, California has a large number of active faults with high “loading rates”—faults that are close to movement at any given time and that are susceptible to induced seismic activity in response to relatively low changes in pressure or shear stress perturbations. In other words, even lower levels of disturbance by fracking and related activity could trigger earthquakes in California.

Second, fracking and wastewater injection in California take place at much shallower depths than in other parts of the country. These activities occur “within about the same depth range” as the faults that cause the bulk of seismic activity in California. The CCST reviewed seismic data and wastewater injection records in the Santa Maria basin in California and found a link between injection at two wastewater disposal wells and a cluster of earthquakes that “suggested a relationship between the [earthquake activity] and the combined effect of the pressure increase in these wells.”

Taken together, “the overall potential for seismicity to be induced by wastewater injection may be at least as high in California as in the central U. S. Furthermore, some magnitude 5 to 6 earthquakes are observed to occur at relatively shallow depths in California, which suggests that induced earthquakes could be at least as large as those experienced to date in the continental interior.”

Risks to Wildlife and Vegetation

Hundreds of federally and state-protected species live in habitats in or near oil fields where fracking happens regularly.

The report estimates that 33,000 hectares (81,545 acres) have been harmed so far by fracking and other well stimulation. The majority of habitat loss caused by fracking has occurred in Kern and Ventura counties. In Ventura County, oil fields fall partially within the Los Padres National Forest, which provides habitat for more than 100 federal or state listed species. Areas in which substantial amounts of fracking-enabled oil development has occurred overlap with critical habitat for the California condor and steelhead salmon.

The report notes that habitat damage is permanent—restoration work and natural revegetation do not restore sites to their pre-disturbance value for native species.

Besides habitat destruction, the report lists several other ways in which fracking harms wildlife, including exposure to toxic wastewater, spills into surface waters, increased traffic, invasive species, diverting water sources, noise and light pollution, and litter ingestion.

The CCST notes that percolation pits are of particular concern because they attract wildlife and expose them to harmful chemicals. While mandatory protective netting prevents some harm, the study estimated that only 24 percent of pits have protective netting.

Risks from Offshore Fracking

Oil companies have fracked hundreds of offshore wells in state and federal waters off the California coast, and the report was critical of the lack of information available about these activities. While operators in federal water are allowed to discharge fracking wastewater directly into the ocean, there are no studies on this waste fluid’s effects on the marine environment. Federal regulators do not even keep track of fracking offshore.

The lack of toxicity data for 31 of the 48 chemicals known to be used in offshore fracking presents a “significant problem,” according to the report. The CCST also reports that offshore spills are commonplace. From 2009 to 2014, there were 170 spill incidents offshore. Given the lack of data on offshore fracking, the science panel recommends more studies be conducted to assess its potential harms and any alternatives to ocean disposal.


The CCST report confirms what other studies have previously demonstrated: fracking and other oil and gas activities present substantial risks to our health, drinking water, and safety. While there are still major data gaps that prevent the public from knowing the true extent of the dangers, existing studies provide ample evidence that the risks are simply unacceptable. Governor Brown’s plea to give science a chance has been answered, and the science shows conclusively that fracking is an unsafe practice for numerous reasons.

Based on the science, the only way to protect the public and the environment from the dangers of fracking is to prohibit the practice. In addition, science-based setbacks to prohibit all wells near where people are exposed to the dangerous air pollution from all phases of oil and gas production must be instituted immediately.



Scientific Study: No Oil and Gas Wells Should Be Allowed Near Where People Work, Live, and Go to School.