Mining and Water Quality Under the Clean Water Act
| Publication year | 1996 |
| Pages | 93 |
1996, September, Pg. 93. Mining and Water Quality Under the Clean Water Act
Mining districts in the west have long been characterized by severe water pollution caused by a naturally occurring reaction of ore minerals with water and air---a reaction that is accelerated and greatly encouraged when orebearing rock is processed to produce metals. Because mining produces large volumes of waste material that generates this pollution, called acid mine drainage ("AMD") in the mining context, mine sites have the capacity to release pollutants from multiple sources. The federal Water Pollution Control Act ("Clean Water Act" or "CWA") regulates many of these sources through the National Pollutant Discharge Elimination System ("NPDES").(fn1) However, because western metal mining districts frequently contain long-abandoned workings dating back into the last century, ambient water quality may already be severely impaired by uncontrolled AMD.
Because NPDES effluent discharge limitations for new mines are calculated using a wasteload allocation process, the Clean Water Act has produced significant disincentives to re-mining these historic mining districts. On the other hand, little improvement in water quality can be achieved without remediating abandoned mine sites---a task that exceeds the financial and administrative capacity of federal cleanup programs, such as the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 ("CERCLA")(fn2) or its state counterparts (if any). Possible mechanisms for returning surface water to premining conditions involve reconfiguring the liability provisions of existing environmental statutes as applied to mining sites, in order to encourage re-mining and reclamation of previously disturbed areas. This paper examines the existing regulation of mining under the CWA, discusses the inherent conflicts between permitting and reclamation, and reviews possible amendments to the CWA that would eliminate those conflicts.
Acid rock drainage ("ARD") is the result of contact between sulfide minerals, water and oxygen, and consists of metal-bearing acidic leachate produced by the oxidation of the sulfides. The nature and extent of ARD at a particular site depends on the site's physical and geochemical characteristics. ARD may be "natural" in a mineralized region, as a product of weathering processes,(fn3) but mining activities greatly enhance its generation (referred to in this context as AMD). Spent ore, tailings and other waste material, in addition to underground and surface workings, all increase the site's potential to generate AMD.(fn4)
Because mining for coal and other minerals exposes a huge volume of rock material to both water and oxygen, AMD generation is one of the most difficult environmental problems facing the mining industry.(fn5) AMD is considered a "pollutant" within the context of both the CWA and CERCLA,(fn6) because on entering surface water, it creates acidified water laden with dissolved metals or metals-contaminated sediments, impairing or destroying aquatic life and interfering with other uses.
Under CWA § 305, each state is required to report to the Environmental Protection Agency ("EPA") on the water quality of all navigable waters within its boundaries, including a description of the nature and extent of nonpoint source pollution. According to Colorado's 1994 305(b) report summary tables, 3,897 of the state's 35,112 miles of river do not support their designated uses, in full or in part.(fn7) The summary text states that nonpoint sources associated with resource extraction activities (that is, mining) have a major impact on 224 river miles that do not support designated uses, and a moderate to minor impact on 1,012 similarly impaired segments.(fn8)
Moreover, of the Colorado stream segments that do not fully support designated uses, metals cause by far the greatest impact on water quality.(fn9) In the Platte, the Arkansas, the San Juan (Animas), the Upper Colorado and the Rio Grande River basins, historic mining activity has been identified as the primary origin of metals in surface water.
Acid drainage also is produced naturally in many mineralized areas because sulfide minerals may be exposed to water and oxygen through erosive processes. In Colorado, for example, several tributaries (Iron Creek, Alum Creek, Bitter Creek---the names are evocative) of the Alamosa River are naturally high in aluminum, iron and acidity, due to natural acid drainage, and contribute to the impairment of uses in the lower Alamosa.(fn10) A similar mechanism
may affect water quality in the upper Animas River basin, where scientific studies are underway to evaluate the relative contributions of natural and mining-derived acid drainage.(fn11)
Although naturally elevated concentrations of metals and acidity should, in theory, be reflected in the use designations and water quality standards established for streams in such areas, it is in practice difficult to distinguish natural acid drainage from ARD. Therefore, existing water quality standards may not represent attainable goals in some mineralized areas even in the absence of mine-derived pollution. Regardless of the source of pollution in mineralized areas, water quality standards can be changed only when the corresponding designated use also is changed. However, because the Clean Water Act promotes the designation of uses that would enhance water quality,(fn12) the EPA enacted regulations that limited the states' ability to downgrade previously designated uses.(fn13)
If a state desires to downgrade a use so that the water does not have to be clean enough to support fishing or swimming, the state is required to conduct a "use attainability analysis" showing that it is not possible to attain fishable, swimmable water within a reasonable time, before the EPA will approve the redesignation.(fn14) In Colorado, for example, a stream classification may be downgraded only under limited circumstances(fn15)---either through a demonstration that the previous classification did not represent actual beneficial uses and had no basis in fact, or through the use attainability analysis.(fn16)
The use attainability analysis requires a demonstration that the present classification is not being attained, nor can it be within a twenty-year period, due to various factors that include the presence of naturally occurring pollutants.(fn17) Although the use attainability mechanism could provide some relief for potential dischargers, the process may be too expensive, technically challenging and time-consuming for individual dischargers to pursue the option. In Colorado, such studies are rare, although the Department of Natural Resources/Division of Minerals and Geology has completed a use attainability analysis of the Alamosa River as part of the Summitville Superfund cleanup.(fn18)
Furthermore, from an environmental perspective, it might be undesirable to change a use designation, since such a change would effectively eliminate any incentive to return the water body to its pre-existing state and uses. A temporary waiver of standards would conflict less with the statutory mandate to maintain and restore water quality.
Section 303(a) of the CWA requires that each state develop and promulgate its own water quality standards, in order to protect the designated uses of state waters, such as water supply, recreation, fish and wildlife habitat or industrial purposes. States also are required to identify those waters for which the effluent limitations are not stringent enough to ensure that the applicable water quality standards will be met(fn19)---where water quality is already degraded, for any reason, there is less "room" for additional pollutants, and more stringent effluent limitations may be necessary.
The state is required to rank these waters as "water quality limited segments" ("WQLS") in terms of priority according to the severity of the pollution and the desired uses of the water.(fn20) Based on the priority scheme, the state must then develop a Total Maximum Daily Load ("TMDL") for each pollutant, which is an estimate of the amount of that pollutant from point and nonpoint sources that can be added to the stream without causing violation of the water quality standards.(fn21)
The TMDL is translated into effluent limitations through a mass-balance analysis of the point and nonpoint sources (wasteload and load allocation, respectively).(fn22) Based on the TMDL, the wasteload allocation assigns portions of that load to the various point sources along the affected stream segment. Under the NPDES, established at CWA § 402, the EPA may issue a permit for the discharge of pollutants, provided that the discharge will meet the technology or water-quality-based effluent limitations established for the relevant class or category of point sources.(fn23) Because an NPDES permit must protect the water quality of the receiving stream, if technology-based limits will not ensure compliance with water quality standards for certain pollutants, the permit may include water-quality-based limitations for those constituents.
Depending on the degree to which water quality in a stream segment is already impaired, however, a permit that imposes water-quality-based effluent limitations may effectively equal a zero discharge requirement. For example, Table 4 of the Colorado 1994 305(b) Report designates certain segments "water quality limited---allocated."(fn24) This designation means that the assimilative capacity of the segment has been allocated among existing point and...
To continue reading
Request your trial