Evaluation of Water Quality, Suspended Sediment, and Stream Morphology with an Emphasis on Effects of Stormflow on Fountain and Monument Creek Basins, Colorado Springs and Vicinity, Colorado, 1981 through 2001
by Patrick Edelmann, Sheryl A. Ferguson, Robert W. Stogner, Sr., Marianne August, William F. Payne, and James F. Bruce
Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 02-4104, 59p., 22figs.
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Abstract
This report documents water quality and suspended sediment with an emphasis on evaluating the effects of stormflow on Fountain Creek Basin in the vicinity of Colorado Springs, Colorado. Water-quality data collected at 11 sites between 1981 and 2001 were used to evaluate the effects of stormflow on water quality. Suspended-sediment data collected at seven sites from 1998 through 2001 were used to evaluate effects of stormflow on suspended-sediment concentrations, discharges, and yields. Data were separated into three flow regimes: base flow, normal flow, and stormflow.
A comparison of stormwater-quality concentrations measured between 1981 and 2001 to Colorado acute instream standards indicated that, except for isolated occurrences, stormwater quality met acute instream standards. At several sites, 5-day biochemical oxygen demand, fecal coliform, and selected nutrient concentrations tended to be highest during stormflow and lowest during base flow. Dissimilar to the other nutrients, dissolved nitrite plus nitrate concentrations generally were highest during base flow and lowest during stormflow. Most dissolved trace-element concentrations associated with stormflow decreased or showed little change compared to base flow. However, median concentrations of total copper, iron, lead, nickel, manganese, and zinc for stormflow samples generally were much larger than nonstorm samples. The substantially larger concentrations of total copper, iron, lead, nickel, manganese, and zinc measured at site 5800 during stormflow as compared to other sites indicates a relatively large source of these metals in the reach between sites 5530 and 5800. Semi-volatile organic compounds in samples collected during stormflow were detected relatively infrequently at the four sites monitored; however, analysis of pesticide data collected during stormflow showed a relatively frequent detection of pesticides at low levels. Nitrogen, phosphorus, and particulate trace-element loads substantially increased during stormflow.
Suspended-sediment concentrations, discharges, and yields associated with stormflow were significantly greater than during normal flow. Depending on the site and year, suspended-sediment concentrations associated with storm-flow generally were 3 to10 times greater than concentrations measured during normal flow, and suspended-sediment discharges were usually more than 10 times greater during stormflow. The April through October cumulative suspended-sediment discharges and streamflows were largest in 1999 at all sites. Although large spatial variations in suspended-sediment yields occurred during normal flows, the suspended-sediment yields associated with stormflow generally were more than 10 times greater than the suspended-sediment yields that occurred during normal flow. The smallest suspended-sediment yields generally were less than 1 ton per day per square mile during stormflow. The largest suspended-sediment yields occurred at sites located in the Cottonwood Creek Basin and were greater than 10 tons per day per square mile.
Table of Contents
Abstract
Introduction
Purpose and Scope
Description of Study Area
Land Use
Acknowledgments
Methods of Investigation
Precipitation, Streamflow, and Stormflow
Water Quality
Comparison of Water Quality between Base Flow, Normal Flow, and Stormflow
Onsite Measurements
Biochemical Oxygen Demand and Fecal Coliform Bacteria
Nitrogen and Phosphorus
Trace Elements
Semivolatile Organic Compounds and Pesticides Associated with Stormflow
Loads for Stormflow and Nonstormflow
Nitrogen and Phosphorus
Trace Elements
Comparison of Water Quality of Stormflow between Pre-1998 and Post-1997 Periods
Onsite Measurements, Biochemical Oxygen Demand, and Fecal Coliform Bacteria
Nitrogen and Phosphorus
Trace Elements
Comparison of Water Quality of Stormflow to Instream Standards
Ammonia and Nitrate Nitrogen
Trace Elements
Semivolatile Organic Compounds and Pesticides
Suspended-Sediment Concentrations, Discharges, and Yields
Annual Variations in Suspended-Sediment Concentrations, Discharges, and Yields
Spatial Variations in Suspended-Sediment Concentrations
Spatial Variations in Suspended-Sediment Discharges
Spatial Variations in Suspended-Sediment Yields
Stream Morphology
Sediment-Transport Capacity
Descriptive Assessment of Changes in Channel Morphology
Monument Creek
Cottonwood Creek
Fountain Creek
Summary
Selected References
