Impact of a Changing Climate on Fine Particulate Concentrations in Butte, MT

A model was developed to assess the potential change in PM2.5 concentrations in Butte, Montana over the course of the 21st century as the result of climate change and changes in emissions. The EPA AERMOD regulatory model was run using NARCCAP climate data for the years of 2040, 2050, 2060 and 2070, and the results were compared to the NAAQS to determine if there is the potential for future impacts to human health. This model predicted an average annual concentration of 15.84 µg/m3 in the year 2050, which would exceed the primary NAAQS of 12 µg/m3 and is a large increase over the average concentration from 2010 – 2012 of 10.52 µg/m3. The effectiveness of a wood stove change out program was also evaluated to determine its efficacy, and modeled results predicted that by changing out 100% of inefficient stoves with an EPA approved model, concentrations could be reduced below the NAAQS.

Geochemical Assessment and Separation of Source Waters in the Upper Boulder River Watershed Near Boulder, MT

Environmental samples were collected at three surface water sites between 5/21/2011 and 11/21/2014 along the Upper Boulder River near Boulder Montana. The sites were located at Bernice (within the mountain block), near the High Ore drainage (near the mountain block/basin transition), and at the USGS Gauging Station near Boulder, Montana (within the basin). The parameters measured in the field were SC, temperature, and alkalinity with occasional pH measurements. We collected samples for anions, cations, and stable isotopes in the catchment. We identified endmembers by sampling snow and groundwater and determined from available data an approximate endmember for rain, snow, and groundwater. We used temporal and spatial variations of water chemistry and isotopes to generate an endmember mixing model. Groundwater was found to always be an important contributor to river flow and could increase by nearly an order of magnitude during large snowmelt events. This resulted in groundwater comprising ~20% of total river flow during snowmelt at all sites. At peak snowmelt we observed that near surface water contributions to the river were from a mixture of rain and snow. Soil water, though not sampled, was hypothesized to be an important part of the hydrologic story. If so, the endmember contributions determined in this study may be different. Groundwater may have the highest variation depending on water chemistry of shallow soil water.