ScholarWorks at University of Montana

The Opportunity Ponds Wetland is a 550 acre wetland creation located three miles east of Anaconda Montana. In 2009 the first 220 acres of wetland planting was completed. Careful design, excavation and site shaping, along with diligent quality assurance and highly professional contractors have resulted in exceptional plant establishment.

The site was historically used as a repository for tailings from the smelting of copper ore. Remediation of the tailings facility is being conducted by capping the tailings ponds with soil material obtained from nearby borrow areas. The depleted borrow areas that were used to develop soil materials are being developed as wetlands. When complete an estimated 550 acres of wetland area will be created on the site. Natural appearing features are being shaped for each wetland area and cover soils are being applied.

The goal is to restore the site to functional vegetation communities that reflect natural wetland habitats in the Upper Clark Fork River (UCFR) Basin. Seeding and planting plans correlate to the topographic gradient and hydrologic regime that has been established. The plants in the vegetation list are species observed within native wetland areas close to the site. Communities are arranged in “planting zones” from upland to open water. Wetland seed was collected from the UCFR Basin and plants are custom grown from that seed. Stringent specifications for plant production and installation were developed and oversight of planting activities is on-going.

We are developing novel ways to restore native plant species diversity in the uplands of the Upper Clark Fork Basin (UCFRB) in areas damaged by releases of hazardous substances by mining companies over more than 100 years. The desired future condition of upland plant communities in the UCFRB is to have sustainable plant communities that are diverse in native plant species and provide ecosystem functions such as nutrient cycling, wildlife habitat, soil conservation and weed resistance. We are in the sedond year of a three year demonstration project with objectives of increasing plant species diversity and developing plant communities resistant to invasion by exotic plant species (weeds). We are developing “forb sods” comprised of a diverse mixture of native forbs some grasses and some small shrubs. These sods will be planted in small patches that will serve as dispersal sources to spread diversity over larger areas. Patches may be placed on “micro-ridges” of clean soil placed on existing caps or reclaimed areas. To supply the necessary diversity we will collect seeds and propagate via tissue culture, native plants from remnant existing plant communities in the UCFRB near Butte. As we do this we will select plants that appear to be weed resistant (are healthy and growing among weeds). We will produce small seed orchards at Montana Tech for the species we use in the forb sods and for weed resistance.

Since the recent removal of contaminated sediment, upper Silver Bow Creek has shown a decrease in concentrations and loads of toxic metals. However, nutrient concentrations in the stream are extremely high, which leads to uncontrolled growth of algae and rooted macrophytes each summer. The Butte waste-water treatment plant (WWTP) discharges > 10 kg/h NH4-N and > 1 kg/h PO₄-P. The WWTP outfall can be as much as 50% of the total flow in Silver Bow Creek during drought periods. Microbial oxidation of ammonium causes a 2-3 km long “dead zone” marked by a drop in dissolved oxygen concentrations to hypoxic levels during summer night-time periods. The dead zone is also marked by large diurnal oscillations in the concentrations of ammonium, nitrate, and nitrite, with higher NH₄/NO₃ ratios at night. The stable isotopic compositions of ammonium and nitrate show dramatic changes over short spatial and temporal scales. Notable trends include an increase in δ¹⁵N-NH₄ and a decrease in δ¹⁸O-NO₃ with distance downstream. Values of δ¹⁵N-NO₃ vary in a more complex fashion. These changes in concentration, speciation, and isotopic composition of nutrients reveal much in terms of the biogeochemical processing of nutrients in the stream, but make it very difficult to collect a “representative sample” for monitoring or scientific purposes. Fortunately for the Clark Fork River, the Warm Springs treatment ponds capture and store the majority of the nutrient load passing down Silver Bow Creek. Unfortunately, the “over-ripe” nature of the treatment ponds causes seasonal release of dissolved arsenic from the pond sediment.

The Development of Acid/Heavy Metal Tolerant Releases (DATR) project, was initiated in 1995 to address a critical need for native plants adapted to the edaphic and climatic conditions characteristic of the Anaconda – Butte area. The goal of the project was to select plant materials demonstrating superior tolerance of low pH and/or heavy metal contaminated soils that are also adapted to the severe environmental conditions characterized by the intermountain foothills and mountains near the Upper Clark Fork River Basin (UCFRB).

To date, 130 seed collections of 72 native species of grasses, forbs, and woody plants have been made within the UCFRB. These collections have been planted at various study sites where they are compared to non-local native and introduced plant species. Several grass, forb, and woody species indigenous to the UCFRB have demonstrated superior growth and vigor on amended acidic, heavy metal-contaminated soils at varying elevations in the Anaconda area. As a result, several accessions have been released through the DATR project using the Pre-Varietal release mechanism.

Opportunity Germplasm Nevada bluegrass is one of three grass selections made from indigenous material collected near Anaconda, Montana and tested at the Stucky Ridge CEP. In 2006, this selection proved significantly (ANOVA; Tukey; p=0.05) superior to four other seed sources (2 indigenous; 2 cultivars) for percentage stand cover, vigor rating, and biomass production on a lime and fertilizer amended site.

The Upper Clark Fork River is the site of one of the most well known and complex remediation & restoration efforts in the world. Over 100 years of mining & smelting in the upper watershed resulted in over 100 miles of river designated as a USEPA superfund site, mandating remediation of hazard and reclamation of lost resources. Silver Bow Creek, the focus of this paper, suffered from sediment loading that contained elevated levels of heavy metals toxic to aquatic life and humans. Toxic sediments settled in the streambed and deposited in the floodplain during overbank events. The contamination was so extensive that removing much of it required complete reconstruction of the stream channel and revegetation of the floodplain. Restoration efforts have created what will hopefully be “the last best disturbance”, so that Silver Bow Creek can recover to an ecologically viable system. To learn from the Silver Bow Creek experience, a rigorous monitoring scheme is in place to evaluate the progress of the restoration. The objectives of these analyses are to 1) Evaluate methods for homogenizing benthic invertebrate data from multiple sources and analytical methods. 2) Describe trends in both historic and current data. 3) Compare trends in Silver Bow Creek to trends from reference reaches. 4) Hypothesize limiting factors for benthic invertebrate recruitment in restored areas.