ScholarWorks at University of Montana

This presentation will provide an overview of the Clark Fork River Basin Task Force and the Clark Fork Basin Watershed Management Plan which it adopted in 2004. In addition it will summarize a key Task Force initiative, obtaining a block of water from Hungry Horse reservoir to provide for new basin water uses and increase the security of existing uses based on water rights junior to lower Clark Fork basin hydropower water rights.

In the arid Inland Northwest, water is undoubtedly the most important natural resource. Western Montana’s Clark Fork River basin is no exception. As the population of western Montana continues to grow, the Clark Fork River basin remains in de facto closure to establishing new water rights. Also, since there is no “growing communities doctrine” in Montana, communities cannot expand their rights to accommodate potential growth. It is therefore essential for communities to know the legal entitlements each have to water amounts. This assessment of municipal water rights and systems in the Clark Fork River basin was conducted by ascertaining the volume(s) and maximum flow(s) of each water right, analyzing the volume of water used annually, and projecting future water consumption amounts for the next 20 years based on their county’s projected population growth rates. Other information gathered for each community’s assessment include water conservation measures, water-related infrastructure, and metering. Interviews of water system managers/operators were conducted to gage their level of understanding of water resource issues and policies. It appears that while several communities in the Clark Fork River basin will have enough in water rights for the next 20 years, other communities such as Seeley Lake, Hamilton, and Missoula are more likely to experience difficulties in having sufficient quantities in water rights in the future.

Bioaccumulation studies of a resident aquatic organism can provide a direct indicator of bioavailable metal in mine-impacted rivers. This approach is supported by concurrently evaluating bed sediment metal concentrations and water quality data. We examine the effectiveness of mine waste remediation in the Clark Fork River using a resident biomonitor (Hydropsyche spp., O: Trichoptera) and streambed sediment. Over a 19-year period, Cu concentrations declined in both indicators at the two most upstream stations, a pattern coincident with remediation events. Sediment Cu declined at most stations along the 200 km study reach. However, Cu concentrations in Hydropsyche in the middle (85 km) and lower (190 km) reaches were significantly influenced by total annual discharge, masking the impact of remediation on bioaccumulation, at least to date.

A biodynamic model was used to make predictive assessments of Cu bioaccumulation under varying metal exposures. We experimentally-derived physiological constants and used site-specific geochemical field conditions to predict Cu bioaccumulation in Hydropsyche (Hydropsyche is a useful proxy for metal exposure in sensitive species). Hydropsyche has a fast Cu uptake and loss rate. However, dietary Cu influx is ~3-fold higher than dissolved influx, suggesting that Cu uptake from food prevails in nature for that species. Bioaccumulation data from the Clark Fork was used to validate this model. The model under-predicted Cu concentrations in Hydropsyche by ~70% when only dissolved Cu concentrations are considered. However, predicted concentrations fall within range of observed values when dietary influx is incorporated into the model. Ongoing field monitoring coupled with biodynamic modeling is a unique approach that strengthens our predictive capabilities as metal exposure conditions change.

Remediation of river systems contaminated with mine waste, such as the Clark Fork, is concerned with reducing metal inputs from sources, thereby mitigating exposures to resident species and permitting ecological recovery. This process implies the presence of an exposure and biological response relationship. Identification this relationship within the context of multiple stressors could have utility in critically evaluating risk management plans. We analyzed the response of the benthic macroinvertebrate assemblage to Cu by merging data collected by monitoring programs within the Clark Fork Basin. A correlation matrix identified environmental gradients within the entire dataset (space and time) and these were correlated against taxa richness, a measure of biodiversity. Results indicated that Cu exposure was the most important explanatory variable for observed richness patterns. Analysis of site-specific temporal changes suggested that a gradual decline in Cu exposure corresponded with increased taxa richness at sites immediately downstream of the Warm Springs Treatment Ponds. At sites further downstream, however, the influence of Cu was confounded with annual fluctuations in discharge, which reduced richness during years of above average discharge. When paired Cu exposure and richness data for all sites and years were regressed, strong statistical relationships emerged, suggestive of exposure-response relationships. Further study is aimed at establishing the accuracy of these relationships and in evaluating their utility to risk management.

Stream restoration is currently a multi-billion dollar, nationwide enterprise enjoying the focus of numerous professional organizations, universities, policy, and citizen groups. The challenge of restoring damaged riverine ecosystems has driven interdisciplinary river science and policy as no other contemporary catalyst—but it hasn’t always been that way. The earliest years of restoration, or more appropriately named “fish habitat manipulation” in Montana (and nationwide) evolved from “make-work” programs during the 1930’s depression. Subsequent efforts in the 1960’s and 1970’s drew from that experience and traditional civil engineering, river mechanics. The Rosgen-based enterprise, initiated in the 1980’s, spawned a new geomorphic approach to river restoration, brought fluvial geomorphology out of the closet, helped create the “river-restoration market”, and ultimately provided incentives for academics to contribute to the current state of the art.

Montana has both lagged and lead the nation in river restoration and preservation efforts. The Stream Protection Act of 1963 and Natural Streambed and Land Preservation Act of 1975 established permitting systems requiring integration of protection measures into stream alterations. The River Restoration Program (now known as Future Fisheries) enacted by the 1989 legislature recognized conservation of streams is of “vital social and economic importance to Montana” and established a funding for river and fishery restoration. Other programs including MTDEQ’s 319 Program and DNRC’s Loan and Grant Program provide additional funding sources. Montana has developed a vibrant river-restoration industry with over 30 Montana-based consultants and several University programs (MSU’s Watercourse and UM’s Center for Riverine Science) providing access to rapidly improving, cutting-edge science essential to effective stream restoration.