INADEQUATE STATE OIL AND GAS REGULATIONS THREATEN GROUNDWATER RESOURCES, STUDY FINDS by PSE Healthy Energy, March 12, 2018
OAKLAND, CA, MARCH 12, 2018 — Definitions of “protected groundwater” in 17 state oil and gas regulations are inconsistent and in many cases less protective than federal regulations used by the U.S. Environmental Protection Agency (EPA) and the U.S. Bureau of Land Management (BLM), according to a study published Friday, March 2, 2018 in Current Opinion in Environmental Science & Health. The findings demonstrate that the nation’s water supply is vulnerable to contamination from oil and gas production and wastewater disposal despite federal protections for groundwater, according to the study led by PSE Healthy Energy, an Oakland, California-based energy research institute.
Because of an exemption in the Safe Drinking Water Act, states are not required to protect groundwater to federal standards during hydraulic fracturing. Thus, individual state definitions for protected groundwater determine how water resources are safeguarded during hydraulic fracturing.
Groundwater is vulnerable to contamination from chemicals used in oil and gas production through several pathways. During hydraulic fracturing operations, stimulation fluids — mixes of chemicals that often include toxins and carcinogens — can be injected into or near geological formations that contain groundwater for potential current and future use as water supply. Stimulation fluids can also reach the water supply through cracks or wear in casings or cement that contain production chemicals within the well.
The researchers recommend that criteria defined by the EPA for an Underground Source of Drinking Water (USDW) — including, for example, salinity levels in brackish (slightly salty) water — be consistently used to define protected groundwater in state oil and gas regulations.
“Continued unconventional oil and gas development directly in and below formations containing groundwater resources highlights the need for all states to protect groundwater to a single, federally defined standard,” said Dominic DiGiulio, a PSE senior research scientist and lead author on the study. “Lax definitions result in lax protections. Protecting groundwater resources is vital for the U.S. economy and the wellbeing of our citizens, especially with increasing demand and climate change impacts such as sustained droughts,” said DiGiulio, who worked on hydraulic fracturing and other issues at the EPA for 31 years.
Because of increased water demand, sustained droughts, and reduction in cost to desalinate water, brackish groundwater is increasingly being used for the water supply, including for drinking, food-crop irrigation and household uses. Inadequate standards leave brackish groundwater resources more vulnerable to contamination during oil and gas production, the researchers say.
“Degrading brackish aquifers decreases water security and increases risk of people being exposed to waterborne contaminants now and into the future,” said Seth Shonkoff, a visiting scholar at the University of California, Berkeley, who is PSE’s executive director and a co-author of the study, titled “The need to protect fresh and brackish groundwater resources during unconventional oil and gas development.”
Existing Standards and Practice
Due to the large variations in language and defining criteria, many state oil and gas regulations cannot be assumed to protect USDWs. For example:
In Alabama and New Mexico, protection of USDWs appears discretionary through use of terms such as “reasonable” potential for use.
In Montana, West Virginia and Wyoming, protection of groundwater is explicitly removed during oil and gas development.
In Louisiana and North Dakota, undefined terms such as “freshwater” are used to define protected groundwater.
In Colorado and Texas, protection of USDWs depends on the location of the oil and gas field.
California requires monitoring of USDWs during hydraulic fracturing but, in an apparent contradiction, defines protected groundwater at a lesser standard than USDWs.
Definitions for protected groundwater during unconventional oil and gas development appear to be equivalent to criteria for USDWs in five states, the study found: Kansas, Mississippi, Oklahoma, South Dakota, and Utah. However, researchers say that despite these definitions, production well and water data indicate that oil and gas development nevertheless occurred in formations containing USDWs in those states.
The oil and gas industry has best practices for protecting ground water. For example, The American Petroleum Institute recommends protection of USDWs during hydraulic fracturing. However, industry recommendations are not binding, and researchers found no evidence that the recommendations are followed consistently by all companies and in all situations.
“We need to apply clear and consistent scientific criteria to regulations to ensure that all Americans have access to a clean water supply regardless of which state they live in,” said study co-author Robert B. Jackson, the Michelle and Kevin Douglas Provostial Professor at Stanford University, and a senior fellow at Stanford’s Woods Institute for the Environment and Precourt Institute for Energy.
The researchers plan to expand their analysis of groundwater protection criteria to other oil and gas producing states.
The need to protect fresh and brackish groundwater resources during unconventional oil and gas development by Dominic C. DiGiulio, Seth B.C. Shonkoff, Robert B. Jackson, June 2018, Volume 3, Pages 1–7, Current Opinion in Environmental Science & Health, doi.org/10.1016/j.coesh.2018.01.002
Highlights
- • Freshwater shortages have led to greater use of treated brackish groundwater.
- • Unconventional oil and gas development occurs in formations containing Underground Sources of Drinking Water (USDWs).
- • Criteria defining protected groundwater vary between 17 states evaluated.
- • Protection criteria are often ambiguous and do not protect brackish groundwater.
- • All states should protect groundwater to the federally defined standard of an USDW.
Freshwater shortages in the United States have led to increased use of treated brackish groundwater for domestic, agricultural, and municipal uses. This increased use highlights the need for protecting groundwater resources, especially during unconventional oil and gas development. We analyzed the criteria that define protected groundwater in 17 oil- and natural-gas-producing states. In general, we find that these criteria are ambiguous and do not protect brackish groundwater to criteria established for Underground Sources of Drinking Water (USDWs) in the United States Environmental Protection Agency’s Underground Injection Control Program. This lack of consistent protection, and continuing unconventional oil and gas development in formations containing USDWs, highlights the need for all states to protect groundwater to the same federally defined standard for USDWs to safeguard fresh and brackish groundwater for present and future use.
Keywords
- Hydraulic fracturing;
- Unconventional oil and gas;
- Brackish groundwater;
- Underground Source of Drinking Water
Introduction
Water resources are vital to economic development and the health and well-being of people and ecological communities. Groundwater is the primary source of domestic water supply in the United States for approximately one-half of the population 1 ; ∗2. Furthermore, the proportion of groundwater to total overall water use for irrigation in the United States increased from 23% to 43% between 1950 and 2010 1 ; 3. Groundwater resources are especially important in arid regions of the United States, and globally, experiencing rapid population growth, where surface water rights for irrigation are often fully appropriated [4], and where climate change is expected to further exacerbate water demands in hotter and drier conditions [5]. Balancing groundwater exploitation has become increasingly difficult with the need to maintain baseflow to streams, wetlands, and riparian zones, to prevent land subsidence caused by the compression of depleted aquifers, and to prevent saltwater intrusion in coastal regions [2].
Freshwater is generally defined as water having <1000 mg/L total dissolved solids (TDS) [6], although states such as California define it more broadly (<3000 mg/L) [7]. The United States Geological Survey (USGS) and the National Groundwater Association define brackish groundwater as water having between 1000 and 10,000 mg/L TDS 6 ; 8. Others have defined brackish water as water having between 1000 and 35,000 mg/L (seawater) TDS [9]. The use of treated brackish groundwater for municipal water supply has substantially increased in the United States 10; 11 ; 12 in part because of declining freshwater availability, the difficulty in securing surface water and groundwater legal rights, the high costs of infrastructure required to transport and store fresh water, and advances in membrane technology that have reduced the cost of desalinization.
The increased use of brackish groundwater prompted the USGS to conduct an ongoing national assessment of brackish aquifers containing ≤10,000 mg/L TDS 4; 13 ; ∗∗14. Given the increased demand for fresh and brackish groundwater, the protection of groundwater resources is especially important, including during unconventional oil and gas development. During hydraulic fracturing and acid stimulation, stimulation fluids can be injected into or near formations that contain fresh water or brackish groundwater resources of potential current and future use. Stimulation fluids can also enter fresh water or brackish groundwater through diverse pathways, including compromised cement between the wellbore and the production casing.
The criteria for USDWs established by the United States Environmental Protection Agency (EPA) in its Underground Injection Control (UIC) program under the Safe Drinking Water Act (SDWA) are reasonable starting points for protecting fresh and brackish groundwater in all states. The EPA defined an USDW in the United States Code of Federal Regulations (40 CFR Section 144.3) through two requirements, as an aquifer or part of an aquifer that: 1) supplies any public water system, or that contains a sufficient quantity of groundwater to supply a public water system, and 2) currently either supplies drinking water for human consumption or contains ≤10,000 mg/L TDS and is not an exempted aquifer. Aquifer exemptions enable disposal of waste fluids into formations containing USDWs and can be granted through the EPA’s UIC program under the SDWA. Hydraulic fracturing was exempted from the SDWA under the Energy Policy Act (EPAct) of 2005, except when diesel fuel is used for well stimulation, rendering criteria for a USDW as protected groundwater unenforceable during these activities.
Statues and regulations on federal and tribal lands are determined by the United States Department of Interior’s Bureau of Land Management (BLM). On March 26, 2015, the BLM issued a Final Rule in 43 CFR Part 3160 [15] on the regulation of hydraulic fracturing. The BLM defined “usable” water for protection as water having TDS ≤10,000 mg/L. BLM stated that this criterion is consistent with existing BLM Onshore Oil and Gas Order No. 2 and that “given the increasing scarcity and technological improvements in water treatment, it is not unreasonable to assume aquifers with TDS levels above 5000 ppm [5000 mg/L] are usable now or will be usable in the future” [15]. However, on June 21, 2016, the United States District Court for the District of Wyoming set aside the BLM rule based on the legal ruling that the EPAct of 2005 precluded BLM’s rulemaking [16]. As a result, the BLM rule has not taken effect on federal lands. “To reduce the burden of Federal regulations that hinder economic growth and energy development,” the BLM published a proposal on July 25, 2017 to repeal the BLM rule [17].
Industry has best practices for protecting groundwater, as well. In its guidelines on oil and gas well construction and integrity for hydraulic fracturing, the American Petroleum Institute (API) stated that “at a minimum, it is recommended that surface casing be set at least 100 feet below the deepest USDW” [18]. The Groundwater Protection Council (GWPC), an organization representing regulatory agencies from oil and gas producing states with input from industry, stated that hydraulic fracturing should not occur in formations containing USDWs that have not received an aquifer exemption [19]. In 2015, as a result of recommendations from a water and well stimulation expert panel [20], the California State Water Resources Control Board (CA SWRCB) required monitoring groundwater (monitoring well installation and sample collection) with TDS levels up to 10,000 mg/L during acid stimulation and hydraulic fracturing [21]. The panel stated that monitoring at this TDS level is appropriate because it aligns with EPA’s UIC program and it is “technically and economically feasible to desalinate” water at this level of salinity [20].
Approach
In sum, statements by BLM [15], API [18], GWPC [19], and the water and well stimulation expert panel convened by the CA SWRCB [20] clearly indicate that the use of criteria established for an USDW to define protected groundwater is both technically and economically reasonable. However, definitions of protected groundwater during oil and gas production vary substantially among states [22]. In this paper, we examine definitions of protected groundwater in states where development has either occurred or has the potential to occur in formations containing USDWs to determine equivalency and divergence of definitions used by these states with criteria established for an USDW.
We assessed the USGS National Produced Waters Geochemical Database [23] to identify states where unconventional oil and gas development may be occurring in USDWs. We screened this database for locations of oil and gas production wells with produced water having concentrations of TDS ≤10,000 mg/L. The USGS database contains an identifier for whether produced water samples came from conventional or unconventional production wells, but the accuracy of this identifier is questionable. For instance, produced water samples in the database from the Pavillion, WY, Field are identified as coming from conventional production wells when in reality they came from hydraulically fractured wells [24]. As such, we did not use these identifiers to distinguish produced water samples coming from conventional and unconventional oil and gas production wells. Additionally, we examined regulations in states where unconventional oil and gas development may be occurring in USDWs. Because criteria for protected groundwater are often unclear, we also examined regulations stipulating the minimum depth of surface casing – given that shallow and improperly cased and cemented wells are a primary mechanism through which groundwater can become contaminated from oil and gas development.
Results and discussion
Based on data for oil and gas production wells having produced water concentrations of ≤10,000 mg/L TDS, oil and gas development in brackish groundwater appears to have occurred in thousands of locations across the 17 states we assessed (Fig. 1). Oil and gas activities in brackish groundwater are concentrated in the Rocky Mountain Region, especially the state of Wyoming.
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Fig. 1. Exploration and production wells with produced water concentrations <10,000 mg/L (n = 18,762). Data are from the USGS’s National Produced Waters Geochemical Database [23].
Individual states define protected groundwater quite differently across the United States, including locations where oil and gas activity occurs directly in brackish groundwater (Table 1). Definitions for protected groundwater during unconventional oil and gas development appear to be equivalent to criteria for USDWs in five states: Kansas, Mississippi, Oklahoma, South Dakota, and Utah. However, despite these definitions, well and TDS data illustrated in Fig. 1 indicate that oil and gas development even in these five states occurred in formations containing groundwater with TDS levels ≤10,000 mg/L or formations meeting the definition of an USDW.
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Table 1.Summary of regulations to protect brackish groundwater during unconventional oil and gas development in states having TDS concentrations ≤10,000 mg/L in produced waters.
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State Description of language in regulations to define protected groundwater (reference includes date of rule or last update in rule or statute.) Alabama Surface casing to be set at base of “freshwater-bearing” strata defined as “present or probable future value for domestic, municipal, commercial, stock, or agricultural purposes” [25]. No hydraulic fracturing in coal beds above 399 ft bgs [25]. California The depth of surface casing does not appear to be tied to groundwater protection. “Freshwater zones” (undefined) are protected [26]. A “source of drinking water” is defined as containing <3000 mg/L TDS [7]. For monitoring purposes during well stimulation, “protected groundwater” is defined as containing ≤10,000 mg/L TDS [21]. Colorado When well stimulation is <2000 ft, surface casing must be >50 ft below the base of freshwater (undefined) [27]. The definition of protected groundwater appears to depend on geographic location, basin, and field. In the Denver-Julesburg Basin, surface casing is based on the location of the Fox Hills Formation – a major aquifer system. In other cases, depth of surface casing depends on distance from water-supply wells [27]. Kansas Depths of surface casing vary by county but are tied to protection of “fresh” and “usable” water defined as ≤1000 mg/L TDS and 500 mg/L chloride and ≤10,000 mg/L TDS or ≤5000 mg/L, respectively [28]. Illinois For horizontal wells, surface casing must be >100 ft below the base of the deepest “fresh water” defined as water containing ≤10,000 mg/L TDS for when total stimulation treatment volume is >80,000 gallons in horizontal wells [29]. Protection of USDWs for oil and gas wells or vertical wells and horizontal wells having smaller stimulation volumes is not described [30]. Indiana USDWs are protected during CBM recovery [31]. Surface casing must extend below lowest USDW [32]. Louisiana Surface casing must protect “fresh water” (undefined) [33]. Mississippi Surface casing must be >100 ft below the base of a USDW in production wells used for hydraulic fracturing [34]. Montana The depth of surface casing does not appear tied to groundwater protection. “Freshwater” is defined as water containing <10,000 ppm TDS but is not protected [35]. Groundwater having a specific conductance between 2500 and 15,000 μS/cm is defined as “Class III” water that is not subject to the “nondegradation” provisions [36] of the Montana Water Quality Act [37]. An equation to convert specific conductance to total dissolved solids is not included in the Montana Water Quality Act. New Mexico The depth of surface casing does not appear to be tied to groundwater protection. “Fresh water” is defined as water having ≤10,000 mg/L TDS and is protected unless “no present or reasonably foreseeable beneficial use” [38]. North Dakota Surface casing must protect freshwater strata (undefined) of present or probable value for domestic, commercial, or stock purposes [39]. Oklahoma Surface casing must be >50 ft below the base of “treatable water” defined as having <10,000 mg/L TDS and <5000 mg/L chloride in production wells used for hydraulic fracturing [40]. South Dakota Surface casing must protect “freshwater” defined as <10,000 mg/L TDS 41 ; 42. Texas Surface casing must be >25 ft below “The Base of Usable-Quality Water (BUQW), generally 3000 mg/L TDS or less and other waters known to be used or identified as sources of desalinization water” [43]. Utah Surface casing must reach base of “fresh water” defined as a USDW [44]. West Virginia Surface casing must prevent the migration of gas and other fluids into the “fresh” (undefined) groundwater but “water” associated with oil and gas development [45] or “fresh” water during hydraulic fracturing [46] is exempted from protection. Wyoming The depth of surface casing must be set to” reasonably estimated utilizable groundwater” or “100 to … 120 feet below the depth of any Wyoming Office of State Engineer permitted water supply wells … within a minimum of one-quarter (1/4) mile radius” [47]. “Class V” groundwater is water associated with oil and gas development and has no TDS standard nor any explicitly stated protection [48].
In Alabama and New Mexico, protection of USDWs appears discretionary through use of terms such as “reasonable” potential for use and hence cannot be assumed protective of USDWs 25 ; 38.
In Montana, West Virginia, and Wyoming, protection of groundwater is explicitly removed during oil and gas development 35; 36; 37; 45; 46; 47 ; 48. For example, hydraulic fracturing occurred in formations containing USDWs in the Pavillion, WY Field as documented by EPA 51; 52 ; ∗∗53 and DiGiulio and Jackson [24]. The State of Wyoming however disputes this finding [54].
In California, USDWs must be monitored but are not explicitly protected during both hydraulic fracturing and acid stimulation 7; 21 ; 26. Kang and Jackson [55] found that up of to 35% of historical oil and gas development in the San Joaquin Valley (where most oil and gas development in California takes place) occurred directly in USDWs. Kang and Jackson [55] state that consideration of brackish groundwater meeting the definition of a USDW as a groundwater resource would increase estimated total groundwater resources in the Central Valley by a factor of almost 4 – particularly relevant for California’s recent droughts.
The BLM has also found that well stimulation is occurring in formations containing USDWs. In response to a Congressional inquiry [56], the BLM [57] conducted a review of 706 randomly selected oil and gas production wells (from a population of 86,000 wells) and determined that hydraulic fracturing occurred in formations containing USDWs at 49 of 389 gas production wells (13%) reviewed. The EPA found that ten of eleven coalbed methane basins in the U.S. are located, at least in part, within USDWs and that hydraulic fracturing in USDWs has occurred in some of these basins [49]. The extent of well stimulation in formations containing USDWs remains unknown.
Insufficient vertical separation between USDWs and depths of stimulation is also of concern for groundwater quality. In a nationwide analysis of depths of high-volume hydraulic fracturing, Jackson et al. [58] found that 1% and 5% of high volume hydraulic fracturing in the United States occurred within 300 m and 900 m of the surface, respectively, potentially endangering shallow USDWs. Since fractures induced by hydraulic fracturing can propagate up to 600 m vertically upward [59], deeper USDWs could be impacted by hydraulic fracturing even where it does not occur directly in formations containing USDWs. An independent scientific study of hydraulic fracturing and well stimulation in California arrived at similar findings in the San Joaquin Valley and in the Los Angeles Basin 60 ; 61.
Conclusion
Given increased demands for brackish groundwater, protecting this resource is important, including during unconventional oil and gas development. On lands without federal or tribal mineral rights, states have primacy over the identification and protection of groundwater resources. Although variation in geologic and hydrologic conditions across states suggests the need for some flexibility in defining protected groundwater, in many states criteria used to define protected groundwater are either ambiguous or do not protect brackish groundwater. The use of criteria for an USDW under the USEPA’s UIC Program, used to define protected groundwater in all states, can serve as a baseline to safeguard fresh and brackish groundwater for present and future use. Statements by BLM [15], API [18], and GWPC [19] conclude that the use of criteria established for an USDW to define protected groundwater during unconventional oil and gas development is both technically and economically reasonable. Additionally, the use of criteria for an USDW to define protected groundwater has been successfully applied in the EPA’s UIC program across states indicating regulatory feasibility. USDW criteria should be used as a baseline to protect fresh and brackish groundwater in all states.