Thomas A. Fontaine

Development of a snowfall-snowmelt routine for mountainous terrain for the soil water assessment tool (SWAT)

The soil water assessment tool (SWAT) is a hydrologic model originally developed to evaluate water resources in large agricultural basins. SWAT was not designed to model heterogeneous mountain basins typical of the western United States, and as a result, has performed poorly when applied to mountainous locations. The intent of this study was to increase the versatility of SWAT by developing the capability to simulate hydrology of a non-agricultural mountainous region with a large snowmelt component. A western Wyoming basin, representative of Rocky Mountain basins, was selected to evaluate model performance, identify governing hydrologic processes, and improve the snowmelt routine. An initial evaluation of SWAT performance indicated an inability of the model to represent snowmelt processes. Based on simulation results and field observations, algorithms were developed which use elevation bands to distribute temperature and precipitation with elevation. Additional routines which control snowpack temperature, meltwater production, and areal snow coverage were designed to simulate the influence of season and elevation on the evolution of basin snowpack. The development of the new snowmelt algorithms improved the average annual Nash–Sutcliffe R2 correlation between simulated and observed Wind River streamflow from an initial value of −0.70 to +0.86.

ANALYSIS OF FECAL COLIFORM BACTERIA IN SPRING CREEK ABOVE SHERIDAN LAKE IN THE BLACK HILLS OF SOUTH DAKOTA

Spring Creek is a perennial stream that originates above Hill City in the Black Hills of South Dakota. Spring Creek, from the origin to the inlet of Sheridan Lake, has been listed on the 1998 303(d) list of impaired waterbodies for South Dakota for exceeding fecal coliform bacteria water quality criteria. The listed portion of the Spring Creek Watershed is approximately 126 square miles (327 square kilometers). The average annual precipitation in the Watershed ranges from 20 to 24 inches (51 to 61 centimeters) per year. Over 97 percent of the Watershed is ponderosa pine forest. A water quality monitoring program was completed from May 2002 through July 2003. Water quality data collected for this reach of Spring Creek indicate that the stream does not meet the water quality criterion for the beneficial use of immersion recreation. Immersion recreation has the most stringent water quality criteria for fecal coliform bacteria in this reach. For this section of Spring Creek from May 1 to September 30 of each year, the criterion requires that the geometric mean of five samples taken over 30 days is not to exceed 200 colony-forming units (cfu)/100 ml and that the daily maximum is not to exceed 400 cfu/100 ml. Water quality data have been collected since 1976 for this section of the creek. The Total Maximum Daily Load for the impaired reach was developed using a watershed approach with the BASINS and HSPF models. Several Best Management Practices (BMPs) were modeled to determine a combination that would bring fecal coliform concentrations down to acceptable levels. The BMPs included reducing the human pathogen sources, a litter control program, buffer zones and filter strips, and better animal waste management. Two possible combinations of BMPs were found that reduced the concentrations in the creek to acceptable levels. Monitoring of fecal coliform concentrations in the impaired reach of Spring Creek should be continued after BMPs are implemented.

Water Quality Management in Rivers and Lakes

ABSTRACT An approach for national water quality management is illustrated based on the 1972 Clean Water Act in the United States. Beneficial uses are assigned to each stream and lake. Water quality standards are developed to support these beneficial uses. A data collection program is used to make periodic evaluation of the quality of water bodies in each state. A bi-annual listing of all impaired water is required, with a schedule for investigations to determine causes of pollution and to develop plans to restore desired water quality. The approach is illustrated using recent water quality investigations of two rivers in the Great Plains Region of the United States.