Fish surveys are conducted by seining streams. Streams in the study area vary from very small streams like the one pictured to larger streams that provide important spawning habitat for fish from the Powder River.

The recent development of coalbed methane resources in the Powder River Basin in Wyoming and Montana and elsewhere in the United States has created a need for scientifically sound information by agency, tribal, and industry resource managers regarding its potential effects on land and water resources and on biota. Coalbed methane development involves the production and disposal of large quantities of coalbed groundwater, often characterized by high concentrations of dissolved ions and/or elevated sodium adsorption ratios, as well as surface environment modifications (roads, pipelines); therefore, the potential exists for substantial effects on aquatic ecosystems. Little research has been conducted on the effects of coalbed methane development on fish assemblages, and no research has compared effects resulting from different product-water management strategies (for example, direct discharge, treatment, disposal in evaporation ponds, re-injection).

The goal of this research is to better understand the influence of coalbed methane development on the aquatic biota and habitats of southeast Montana and northeast Wyoming. The research team’s specific objective is to determine the effect of coalbed methane development on intermittent prairie stream fish assemblages.

The research process includes five complementary approaches:

1. Treatment versus control streams— Fish assemblages in streams in areas of coalbed methane development (treatment streams) were compared to those in streams in areas without coalbed methane development (control streams). Comparisons were only made where appropriate — for example, in similar-sized streams with similar expected physical and biological conditions. Samples were collected by seining according to Montana Prairie Riparian Native Species Study protocols.
2. Upstream versus downstream comparisons— Fish assemblages were compared in areas upstream of development to those in areas downstream of development within the same stream. In the absence of effects, the expected condition was for fish species richness to stay the same or increase in downstream areas. Reductions in species richness at downstream sites would suggest deleterious effects.
3. Pre-development versus post-development samples— In 2005, areas that were without coalbed methane development were identified and sampled, but were scheduled to be developed by 2006. Because of complications with permitting, the areas were not developed in 2006. However, fish assemblage data were compared from streams sampled in the early 1990s (prior to development) to samples that were at the same locations in 2005 and 2006. Samples were collected both in streams in developed areas and in streams in areas without development and assessed if any observed changes were attributable to development or to unrelated temporal trends.
4. Sampling product water streams—There are some formerly ephemeral streams, which now flow perennially as a result of product water discharge. These streams were sampled to determine which, if any, fishes occupy these unique habitats.
5. In-situ acute toxicity testing—The acute toxicity of stream water in areas of development was tested using wild-caught fish held in sentinel cages. This approach was intended to complement observations of fish distributions made during treatment versus control, and upstream versus downstream surveys. Fish were captured in undeveloped areas and placed in cages in developed areas to test for acute toxicity. Fish were also placed in cages in undeveloped areas to control for effects of capturing and caging fish.

Progress to Date:

Field work began in summer 2005 with funding from the BLM and was completed during summer 2006 under WFHI Phase IV. In 2005, 57 sites were sampled, including all treatment, control, and longitudinal sites. Crazy Woman and Salt creeks were sampled for historical comparisons. Water quality samples were collected from each stream and sent to Energy Labs, Inc., in Billings, Montana, for ion analysis. Twenty-four fish species were collected. Treatment streams had a range of 0 to 8 fish species whereas control streams had a range of 1 to 12 fish species. Plains killifish (Fundulus zebrinus) and river carpsucker (Carpoides carpio) were found exclusively in treatment streams whereas channel catfish (Ictalurus punctatus), stonecats (Noturus flavus), shorthead redhorse (Moxostoma macrolepidotum), and plains minnows (Hybognathus placitus) were found exclusively in control streams. Preliminary results were presented at the 2006 Great Plains Fishery Worker Association Meeting and the 2006 Western Division Annual Meeting of the American Fisheries Society.

In 2006, all sites were re-sampled, and 13 additional sites were sampled at locations that had been sampled in the 1990s. Water quality samples were collected from all sites and sent to Energy Labs, Inc., in Billings, Montana, for ion analysis.

A total of 17 fish species was collected at treatment and control streams. Fifteen species were collected in control streams, including 12 native and 3 non-native species. Thirteen species were collected in treatment streams, including 9 native and 4 non-native species. Channel catfish, plains minnow, shorthead redhorse, and stonecats (Noturus flavus) were captured exclusively in control streams. Lake chub (Couesius plumbeus) and plains killifish were captured exclusively in treatment streams. However, all of these species were found infrequently.

Most species were observed during fewer than 20 percent of the 68 sampling events; however, 5 native species were more ubiquitous. Creek chub, fathead minnow, longnose dace, sand shiner, and white sucker were observed during 15 or more sampling events. Longnose dace, sand shiner, and white sucker occurred more frequently at control sites than treatment sites, whereas no common species occurred more frequently in treatment streams. Longnose dace were observed in 14 (38 percent) control samples in 4 (50 percent) streams and in only 3 (10 percent) treatment samples in 2 (25 percent) streams. Similarly, sand shiners were observed in 16 (43 percent) control samples in 5 (63 percent) streams and in only 8 (28 percent) treatment samples in 3 (38 percent) streams. White suckers were observed in 12 (33 percent) control samples in 3 (37 percent) streams and in 7 (24 percent) treatment samples in 4 (50 percent) streams. Creek chub and fathead minnow were observed at similar frequencies at both control and treatment sites.

An index of biotic integrity (IBI; Bramblett et al. 2005) score for northwestern Great Plains streams was computed for each site. The IBI consists of 10 metrics and has a potential range of scores from 0 to 100. Overall IBIs, individual IBI metrics, and species richness were compared between treatment and control streams using ANOVA. The mean IBI score of the fish assemblages in control streams was higher than in treatment streams but the difference was not significant (P = 0.25). Seven of ten mean individual IBI metrics scored higher in control streams, but no metrics were significantly higher in control streams than treatment streams. Similarly, the mean species richness in control streams was higher than in treatment streams but the difference was not significant (P = 0.87).

Treatment streams did not all have equal amounts of CBNG development. Databases containing the locations of CBNG wells were obtained from the Wyoming Geographic Clearinghouse (2007) and the Bureau of Land Management Miles City Field Office. The amount of CBNG development upstream of each site was determined by calculating the number of CBNG wells and well density (number of wells/km2) within the watershed upstream of the sample point using ArcView 9.1. Regression analysis was used to determine whether a significant relationship existed between biotic integrity or its component metrics and the amount or density of CBNG development upstream of each sample site. The amount or density of CBNG development within the drainage areas of treatment streams did not affect fish assemblages. No relationship existed between site IBI scores and the number or density of CBNG wells upstream of sites. The two treatment sites with the highest IBI scores were in relatively dense CBNG development on SA Creek.

Product-water management varied among and within watersheds. We evaluated whether fish assemblages responded differently to the types of water management upstream of the sampling sites. A database of approved Wyoming Pollutant Discharge Elimination System (WYPDES) and Montana Pollutant Discharge Elimination System (MPDES) permits for CBNG product-water was acquired from the Wyoming and Montana Departments of Environmental Quality. Product-water outfalls were designated as discharges to on-channel reservoirs, off-channel reservoirs, or discharges to stream channels. The total number, type, and density of outfalls within the watershed upstream of each sample site were determined using ArcView 9.1 (ESRI 2006; Table 4). Regression analysis was used to determine whether a significant relationship existed between biotic integrity and the total number of product-water outfalls and the number of each type of outfall upstream of each sample site. Product-water management did not appear to have an effect on fish assemblages. No relationship existed between IBI scores and the number of product water outfalls. Similarly, no relationship existed between IBI scores and the number of product water outfalls discharged to on-channel reservoirs, off-channel reservoirs, or stream channels. Index of biotic integrity scores varied widely among sites with similar water management strategies.

Physical properties of water quality were highly variable throughout the study area. No significant differences in physical properties existed between treatment and control streams, but mean specific conductance of treatment streams was higher than control streams. Mean specific conductance was more than 800 µmhos/cm greater in treatment streams than control streams in field observations and laboratory analyses. Specific ion and dissolved metal concentrations were highly variable throughout the study area and few patterns existed among the relationships of fish assemblages to these measures of water quality. Treatment streams had significantly higher concentrations of alkalinity, bicarbonate, and magnesium than control streams.

We compared existing fish assemblage data from streams sampled in the early 1990s (prior to development) to samples that were at the same locations in 2006. In streams that have been developed, lake chub (Cousieus plumbeus), plains minnow, river carpsucker, sturgeon chub (Macrhybopsis gelida), and western silvery minnows (Hybognathus argyritis) were observed in 1995, but were not observed in 2006. However, brown trout (Salmo trutta), largemouth bass (Micropterus salmoides), and spottail shiner (Notropis hudsonius) were not observed in 1995, but were observed in 2006. In undeveloped streams, brassy minnow (Hybognathus hankinsoni) and lake chub were observed in 1995, but were not observed in 2006. However, black bullhead (Ameiurus melas), channel catfish, and plains killifish were observed in those streams in 2006, but not in 1995. We calculated IBI scores for 1994 and 2006 at each site. The mean change in IBI score (Δ IBI) between 1994 and 2006 was not significantly different between treatment and control sites (P = 0.462). Sixty-seven percent of control and 60 percent of treatment sites had higher biotic integrity scores in 1994 than in 2006.

We determined that some product water streams had been colonized by fish. Burger Draw and Beaver Creek were occupied by several species of fish, including fathead minnow (Pimephales promelas), plains killifish, green sunfish (Lepomis cyanellus), and black bullheads. Some sites in product water streams had no fish.

In situ toxicity tests were conducted at a total of 9 sites on 7 streams in July, 2006. Fish growth and survival was not significantly different between streams with and without development. In Squirrel Creek, fish grew and survived in a location below CBNG development where only two fish were observed in the 2005 and 2006 surveys. Summary reports and an educational field guide were distributed to landowners. Preliminary results were presented at the Coalbed Natural Gas Aquatic Task Group Meeting, the 2007 Montana Chapter Annual Meeting of the Wildlife Society, and the 2007 Montana Chapter Annual Meeting of the American Fisheries Society.

Future Activities:

Analyses and a final report in the form of a Master's thesis will be completed by August 2007.

Projected Completion Date and Deliverables:

A detailed final report describing the methods, findings, and management implications of the study will be produced in the January 2008 semi-annual report. At least one manuscript based on this study will be submitted for publication in a peer-reviewed journal. Results will also be presented at scientific meetings.

Partners:

Partners include Montana Fish, Wildlife and Parks, Montana Department of Environmental Quality, US Bureau of Land Management, US Environmental Protection Agency, US Fish and Wildlife Service, Wyoming Fish and Game, US Forest Service, and the coalbed methane industry.

Robert G. Bramblett
Montana Cooperative Fishery Research Unit
Department of Ecology, Montana State University-Bozeman
Bozeman, Montana 59717