A Review of the Potential Effects of Coal Bed Natural Gas Development Activities on Fish Assemblages of the Powder River Geologic Basin

Abstract

Coal bed natural gas (CBNG) development in the Powder River geologic basin (PRGB) may alter water quality, quantity, or aquatic habitats. CBNG product water is generally higher than surface waters in dissolved sodium and bicarbonate and sometimes exceeds toxicity levels for fathead minnows and daphnids. Montana and Wyoming water quality standards do not account for differential ion toxicity; toxicity data for most fishes of the PRGB are lacking, and there are minimal data available on composition of CBNG product water. One field study suggests that CBNG may limit fish distribution. Metals and trace elements in CBNG product water, wetlands, impoundments, sediments, and biological tissues may exceed chronic standards or other biologically relevant thresholds. Product-water dissolved oxygen, pH, and turbidity are comparable to surface waters, but spatiotemporal temperature variation may disrupt natural cues. Increased discharge from CBNG product-water discharge or groundwater depletion may alter the ecology of PRGB streams. Indirect effects may occur if development alters food webs, plant communities, or aquatic habitats. Road construction may increase sedimentation, and stream crossings may fragment fish populations. Impoundments may be a source of non-native fish species. The uncertainty concerning potential effects of CBNG development on fish in the PRGB highlights the need for further research and monitoring.

Fish assemblage associations and thresholds with existing and projected oil and gas development

“…ion concentrations) individually and fail to consider their interacting effects (Davis et al 2009). Groundwater brought to the surface along with oil and gas (i.e.…”

“…Groundwater brought to the surface along with oil and gas (i.e. Roads and pipelines associated with development can represent barriers to fish passage, and in channel impoundments can alter flow regimes and impede fish passage (Davis et al 2009;Farag et al 2010). Water quality standards that are in place often consider constituents (e.g.…”

Effects of coalbed natural gas development on fish assemblages in tributary streams of the Powder and Tongue rivers

“…In the PRGB, CBNG product water (treated or untreated) is disposed of by direct discharge into streams or ephemeral channels, impounded in on‐ or off‐channel reservoirs or used for other purposes if of sufficient quality. Although most impounded water evaporates or infiltrates to deeper ground water, water from unlined reservoirs may reach nearby stream channels by subsurface flow (Davis et al. , 2009).…”

“…However, CBNG development may alter water quality, water quantity or aquatic habitats in ways novel to existing evolutionary frameworks. In the PRGB, product water is typically high in sodium bicarbonate (NaHCO 3 ), whereas surface waters generally are high in dissolved calcium (Ca 2+ ), magnesium (Mg 2+ ), chloride (Cl − ) and sulphate () (Bartos & Ogle, 2002; McBeth, Reddy & Skinner, 2003; Davis et al. , 2009).…”

“…, 2009). However, because both surface water and product water are spatially and temporally variable in the PRGB, the overall salinity of CBNG product water may be either lower or higher than receiving surface waters (Davis et al. , 2009).…”