Beneficial Use Matrix - Environmental Restoration
Impoundments
Impoundments of produced water have been used for a variety of water management practices including disposal by evaporation and/or infiltration, storage prior to subsequent water management option including injection or irrigation, or for beneficial use such as a fish pond, livestock and wildlife watering ponds, or for recreation1. Impoundments are often a combination of management and beneficial use options that include livestock and wildlife watering from wetlands, fisheries and recreational ponds, recharge and evaporation ponds, or other combinations.
Wildlife Watering and Habitat
Some CBM projects in the Rocky Mountain area have created impoundments that collect and retain large volumes of produced water. Provided that the quality of the impounded water is high enough, impoundments can provide a source of drinking water for wildlife and offer habitat for fish and waterfowl in an otherwise arid environment. The impoundments can also offer additional recreational opportunities for hunting, fishing, boating, and bird watching. ALL Consulting compiled information on siting and constructing wildlife-watering impoundments1.
The Montana Department of Environmental Quality classifies CBM produced water as State Water (non-pollutant). Therefore, permitting prior to impoundment use is not required, although discharges are not allowed into state waters. New Mexico Department of the Environment/Surface Water Quality also has permitting regulations which pertain to this specific beneficial use1.
The water quality requirement for wildlife watering and habitat would be similar to livestock watering as described in Beneficial Use for Agriculture page.
Fisheries
CBM produced water could play an important role in the development and creation of new habitat for fish populations. Long-term availability of produced water to supply the fisheries may determine if this option is sustainable, or if this would be a short-term opportunity only.
State, tribal, and Federal water quality regulations have set criteria and standards to protect aquatic life and fisheries, including a designated use for a particular water body; criteria to meet that use; and an anti-degradation policy. The water quality criteria for fisheries are integrated within the state surface water quality classifications and standards. For more information, see Beneficial Use for Discharge page.
An example of state water quality criteria for aquatic life protection can be found the CDPHE Regulation No. 31: The Basic Standards and Methodologies for Surface Water (5 CCR 1002-31) [PDF].
Constructed Wetlands
Constructed wetlands could provide an approach to treat raw produced water or as post-treatment to further clean treated water. Construction of a wetland could increase wildlife abundance, reduce displacement, and enhance diversity by improving quality habitat1.
Constructed wetlands have several constraints on their usefulness: 1) Wetlands require a large amount of land per unit volume of water; 2) A sufficient supply of water is necessary to support the wetland; 3) The source and quality of water may require pretreatment, in some agricultural and municipal cases impaired water must be pre-treated before entering a treatment wetland2; and 4) Absorbed contaminants may be released during high flow events or periods when vegetation decomposition occurs.
A limitation of wetlands in cold climates is that primary functions may be minimal during winter months. A possible solution to this problem would be to spray the inflow water in the air. This would cause the fresh water to freeze (some would evaporate as well), and the remaining water would be more concentrated2.
Wetlands may have significant ecological and environmental impact. They provide areas that can be utilized by wetland birds, animals, and aquatic life. Wetlands can also be utilized for livestock and wildlife watering purposes3. On the other hand, the contaminants in CBM produced water may affect fish and wildlife. For example, research conducted by the USGS has demonstrated acute and chronic sodium bicarbonate toxicity to aquatic species. CBM produced water discharges containing selenium in concentrations above 2 µg/L may cause bioaccumulation in sensitive species4. In addition, if the wetlands are constructed as part of direct discharge, they may change habitat from increased flows and increased erosion. Impacts to downstream users due to direct discharges would be higher with increased flows during traditional low flow periods and increased sedimentation from erosion. Properly designed wetlands can dampen peak flows to mitigate these impacts.
References
- ALL-Consulting, Handbook on coalbed methane produced water: Management and beneficial use alternatives, 2003, for the Ground Water Protection Research Foundation, U.S. Department of Energy, and U.S. Bureau of Land Management, http://www.all-llc.com/CBM/BU/index.htm
- The use of coal bed methane product water to enhance wetland function, 2003, http://waterquality.montana.edu/docs/methane/wetlandenhancement.shtml
- Kuipers, J. R., Technology-based effluent limitations for coalbed methane produced wastewater discharges in the Powder River Basin of Montana and Wyoming, 2004, Draft Report prepared for Northern Plains Resource Council Billings, MT, http://www.northernplains.org/files/Final_BPJ_BAT_8_25_04.pdf [PDF]
- Lynch, K. E., Agency Collection Activities: Coalbed methane extraction sector survey, 2008, Prepared by Trout Unlimited to EPA Docket Center, August 12, 2008 Letter [PDF]