South Fork Flathead River Research Articles

The dam that fly ash built.

When the first concrete was poured in 1949 for the Hungry Horse Dam (Montana, USA), pozzolan cements had already been used in several major North American dams, including Grand Coulee on the Columbia River (diatomaceous earth explored but ultimately not used), Friant on the San Joaquin River and Altus on the North Fork Red River (pumicite) and Bonneville on the Columbia River and Davis on the Colorado River (calcined clay). But Hungry Horse Dam stands out as the first dam constructed using coal combustion fly ash. Utilising 2.4 million cubic metres of concrete, the dam is located on the South Fork Flathead River, one of the tributaries feeding one of the nation's major waterways, the Columbia River, and closely related to the adjacent Glacier National Park. In this respect, Hungry Horse is directly connected to two momentous periods in modern history - the massive adoption in the 1950s of coal as fuel for power plants, and the ongoing threats to fresh water supply and the rapid retreat of alpine glaciers due to global warming. Two concrete cores from this dam, one with fly ash and one without fly ash, are examined microscopically to explore the long-term suppression of alkali-aggregate reaction by fly ash. The core without fly ash exhibits clear evidence of alkali-aggregate reaction, manifested by sandstone coarse aggregate particles with darkened reaction rims. Sandstone coarse aggregate particles of the same lithology in the core with fly ash are without signs of alkali-aggregate reaction. A detailed examination of the darkened rims indicates that alkali-silica reaction products fill the narrow gaps between adjacent sand grains in the sandstone. This alkali-silica gel infilling allows for optical continuity between adjacent sand grains and is responsible for the classic darkened rim associated with the alkali-aggregate reaction.

Upper Sun River Drainage Basin Origin Determined by Topographic Map Interpretation Techniques: Lewis and Clark and Teton Counties, Montana, USA

A new and fundamentally different regional geomorphology paradigm in which massive south- and southeast-oriented meltwater floods flowed across the entire Missouri River drainage basin is tested by interpreting detailed topographic maps of the Montana upper Sun River drainage basin region by trying to explain origins of previously unexplained or poorly explained erosional landforms located upstream from Sun River Canyon (which cuts across Montana’s north-to-south oriented Sawtooth Range). Mountain passes, through valleys, and other drainage divide low points along what are today high mountain ridges, including the North American east-west continental divide, are interpreted to be evidence of drainage routes that once crossed the region. These drainage divide crossings suggest that prior to erosion of present-day upper Sun River drainage basin valleys, massive floods moved in south directions across what are today the north-oriented Middle and South Fork Flathead River drainage basins into today’s upper Sun River drainage basin area and carved a complex of diverging and converging channels into what was probably a low relief surface now represented by the crests of the region’s highest mountain ridges. Further, the map evidence shows how a diverging complex of south- and southeast-oriented upstream Sun River drainage basin flood flow channels changed flow direction to cross the Sawtooth Range in a northeast direction before converging on the Montana plains at a location downstream from Sun River Canyon. The observed upper Sun River drainage basin area topographic map evidence is consistent with the new geomorphology paradigm predictions, in which massive south-oriented meltwater floods flowing across the rising rim of a continental ice sheet created deep “hole” (created by deep ice sheet erosion and ice sheet weight caused crustal warping) are diverted to flow in northeast and north directions into and across deep “hole” space being opened up by ice sheet melting.

ASSESSING THE IMPACTS OF RIVER REGULATION ON NATIVE BULL TROUT (SALVELINUS CONFLUENTUS) AND WESTSLOPE CUTTHROAT TROUT (ONCORHYNCHUS CLARKII LEWISI) HABITATS IN THE UPPER FLATHEAD RIVER, MONTANA, USA

ABSTRACTHungry Horse Dam on the South Fork Flathead River, Montana, USA, has modified the natural flow regimen for power generation, flood risk management and flow augmentation for anadromous fish recovery in the Columbia River. Concern over the detrimental effects of dam operations on native resident fishes prompted research to quantify the impacts of alternative flow management strategies on threatened bull trout (Salvelinus confluentus) and westslope cutthroat trout (Oncorhynchus clarkii lewisi) habitats. Seasonal and life‐stage specific habitat suitability criteria were combined with a two‐dimensional hydrodynamic habitat model to assess discharge effects on usable habitats. Telemetry data used to construct seasonal habitat suitability curves revealed that subadult (fish that emigrated from natal streams to the river system) bull trout move to shallow, low‐velocity shoreline areas at night, which are most sensitive to flow fluctuations. Habitat time series analyses comparing the natural flow regimen (predam, 1929–1952) with five postdam flow management strategies (1953–2008) show that the natural flow conditions optimize the critical bull trout habitats and that the current strategy best resembles the natural flow conditions of all postdam periods. Late summer flow augmentation for anadromous fish recovery, however, produces higher discharges than predam conditions, which reduces the availability of usable habitat during this critical growing season. Our results suggest that past flow management policies that created sporadic streamflow fluctuations were likely detrimental to resident salmonids and that natural flow management strategies will likely improve the chances of protecting key ecosystem processes and help to maintain and restore threatened bull trout and westslope cutthroat trout populations in the upper Columbia River Basin. Copyright © 2011 John Wiley & Sons, Ltd.

Effects of Road Decommissioning on Stream Habitat Characteristics in the South Fork Flathead River, Montana

AbstractPrevious studies have demonstrated the negative effects of roads on stream characteristics important for fish survival; however, few have examined whether decommissioning reverses these adverse impacts. We examined the relationships between the percentage of fine sediment in stream substrate and roads and looked at whether decommissioning had measurable effects on stream habitat in the Flathead National Forest, Montana. We conducted habitat surveys and substrate coring in 12 streams encompassing three watershed treatment types: (1) roadless areas, (2) areas with roads in use, and (3) areas with decommissioned roads. Significant positive correlations were found between the percentage of fine sediment in substrate and various measures of road impact (road density, roads in use, and number of stream crossings). Watersheds with roads in use had higher percentages of fine sediment than those without roads and those with decommissioned roads. Watersheds with high levels of vegetative regrowth on decommissioned roadbeds had a lower percentage of fines in stream sediment. Decommissioning efforts that enhance regrowth may improve stream habitat, although significant effects of these manipulations are difficult to detect through spatial comparisons. Future studies using either before‐after or before‐after‐control designs to evaluate the effects of decommissioning practices on fish and wildlife habitat and populations are needed.

Effects of Thermal Regime on Size, Growth Rates and Emergence of Two Species of Stoneflies (Plecoptera: Taeniopterygidae, Pteronarcyidae) in the Flathead River, Montana

The life histories of two species of stoneflies were compared in adjacent unregulated and partially regulated reaches of the Flathead River in northwestern Montana. Approximately one-third of the discharge in the partially regulated reach is from the South Fork, which is controlled by a hypolimnial-release dam. Responses of winter-emerging Taenionema pacificum to altered environmental conditions included larger nymphal sizes and altered growth rates and emergence times. Pteronarcella badia, a late-spring emerger, responded with differences in population densities and larger nymphal sizes, but not with significantly altered growth rates or emergence times. Monthly mean temperatures were positively correlated (P < 0.01) with mean specific growth rates of F badia but not of 7T pacafacum. Specific growth rates (calculated from measurements of interocular distance) ranged from -0.2 % to 2.6 % /day for T pacificum and from -0.1 % to 2.5%/day for P badia. Growth rates differed during the 2 years of the study as a result of varying discharge regimes and weather patterns. INTRODUCTION Temperature is important in the ecology of aquatic insects (Ward and Stanford, 1982), and differences in life histories of populations in regulated rivers are expected as a result of altered thermal regimes. Timing of life cycles of some species is flexible, and growth rates and emergence times are adjusted in accordance with the prevailing temperature regimes (Nebeker, 1971a, 1971b; Rupprecht, 1975; Hynes, 1976; Vannote and Sweeney, 1980). Warm water temperatures downstream of deep-release dams in winter can accelerate larval development and cause early emergence of adults of certain species (Ward and Stanford, 1979). The Flathead River in northwestern Montana encompasses sites within the same river channel that have different thermal regimes. The confluence of the South Fork (which is regulated by a hypolimnetic-release dam) with the mainstem Flathead River separated two study sites, and permitted comparison of the effects of relatively small changes in temperature on the growth of benthic insects in adjacent reaches of the river. Environmental variables in the partially regulated reach were changed less than in many fully regulated rivers below deep-release dams, such as the South Fork Flathead River. Comparisons of the adjacent unregulated and partially regulated sites facilitated observations of differences between populations which were a result of river regulation, without some of the variation that is commonly associated with between-site habitat differences in adjacent drainage basins. Studies of insect populations in regulated vs. unregulated rivers may allow testing of theoretical models for aquatic biotas (e.g., thermal equilibrium hypothesis, Vannote and Sweeney, 1980). The thermal equilibrium hypothesis predicts that subpopulations of lotic species in nonoptimal thermal habitats are characterized by low population density and small-bodied individuals (Vannote and Sweeney, 1980). The purpose of this study was to investigate the phenology of natural populations of stoneflies in adjacent river reaches differing in thermal regimes. Small environmental alterations caused by a dam provided an experimental situation under natural field con'Present address: 116 S. Park Dr., Arlington, Virginia 22204. 2Author to whom reprint requests should be sent.

A model to forecast short‐term snowmelt runoff using synoptic observations of streamflow, temperature, and precipitation

Snowmelt runoff is forecast with a statistical model that utilizes daily values of stream discharge, gaged precipitation, and maximum and minimum observations of air temperature. Synoptic observations of these variables are made at existing low‐ and medium‐altitude weather stations, thus eliminating the difficulties and expense of new, high‐altitude installations. Four model development steps are used to demonstrate the influence on prediction accuracy of basin storage, a preforecast test season, air temperature (to estimate ablation), and a prediction based on storage. Daily ablation is determined by a technique that employs both mean temperature and a radiative index. Radiation (both long‐ and short‐wave components) is approximated by using the range in daily temperature, which is shown to be closely related to mean cloud cover. A technique based on the relationship between prediction error and prediction season weather utilizes short‐term forecasts of precipitation and temperature to improve the final prediction. Verification of the model is accomplished by a split sampling technique for the 1960–1977 period. Short‐ term (5–15 days) predictions of runoff throughout the main snowmelt season are demonstrated for mountain drainages in western Washington, south‐central Arizona, western Montana, and central California. The coefficient of prediction (Cp) based on actual, short‐term predictions for 18 years is for Thunder Creek (Washington), 0.69; for South Fork Flathead River (Montana), 0.45; for the Black River (Arizona), 0.80; and for the Kings River (California), 0.80.