Oil and Gas at Your Door? (2005 Edition) - Earthworks

Oil and Gas Development and Impacts
PRODUCED WATER
There are a host of health and safety concerns associated with produced water. The quality and
quantity of water removed present threats to human and ecological health; and the removal of
water creates other issues such as potential for underground coal fires, and creation of
pathways for methane to migrate to the surface. All of these issues are discussed later
in this section.
Water Quality
Pumping oil and gas out of the ground produces large volumes of water, which
often contains large amounts of dissolved salts (e.g., chloride, nitrate, nitrite, sodium,
calcium, magnesium and potassium), inorganic substances (e.g., antimony,
arsenic, barium, boron, cadmium, chromium, copper, lead, lithium, mercury, nickel,
silver and zinc); 281 hydrocarbons (benzene, ethylbenzene, naphthalene, toluene,
phenanthrene, bromodichloromethane, and pentachlorophenol) and radionuclides
(e.g., uranium, radon, and radium).
Most produced water has attributes that make it undesirable or unfit for human or agricultural use.
• Oil, sulfur and phenol can be smelled and tasted.
• Studies on produced water from California oilfields have revealed incidents where concentrations
of phenols and arsenic posed a threat to human health. 282
• As mentioned above, benzene is a known human carcinogen and can cause blood disorders,
impacts on the central nervous system, and reproductive effects; and ethyl benzene
and toluene are known to human reproduction and respiratory systems.
• In high enough concentrations, sodium, carbonates, phosphates, borates, sulfates, magnesium,
potassium, iron, fluorine and organic chemicals found in produced water may all
contribute to the deterioration of the water supply. For example, if chloride is present in high
concentrations it can cause water to taste salty, and soap suds will not form as well. And
boron, which is non-toxic to humans in low concentrations, can produce a laxative effect in
animals (concentrations of 40 ppm). 283
• Produced water often has high salinity (dissolved salt content). Total salinities of oil- and
gas-field produced water range from about 1,000 milligrams per liter to more than 400,000
mg/L. The U.S. EPA’s recommended safe drinking-water limit is 500 mg/L. 284 Waters with
salinities between 0 and 400 mg/L are acceptable for all crops; and salinities above 5,000
mg/L are considered too saline for almost all crops. 285 Also, if produced waters are discharged
onto land surfaces, the salts can build up in the soil and affect plant growth.
The concentration of contaminants in produced water varies from region to region and depends
on factors such as the geology, depth of the production zone, age of the well, and well stimulation
techniques. 286
• Radionuclides in produced water are found only in some areas of the country (see discussion
on NORM below).
• In most oil and gas producing areas, produced water from deeper wells has a higher salt
content than water from shallow wells. In basins where the rocks consist mainly of shales
or siltstones, however, fresher water may be found at greater depths. 287
• If wells undergo acidization or hydraulic fracturing, residual chemicals will be removed
along with produced water. The chemicals used vary be operator and geological formation.
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