Streamwater Quality Data from the
2002 Hayman, Hinman, and Missionary Ridge Wildfires, Colorado, 2003
By Anthony J. Ranalli and Michael R. Stevens
Data Series 109
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The citation for this report, in USGS format, is as follows:
Ranalli, A.J., and Stevens, M.R., 2004, Streamwater Quality Data from
the 2002 Hayman, Hinman, and Missionary Ridge Wildfires, Colorado, 2003,
5 p.
Problem
Concern about water-quality issues related to wildfires in Colorado has
intensified because of the wildfires that occurred in Colorado during
the summer of 2002. In 2003, the U.S. Geological Survey (USGS) conducted
water-quality sampling of burned and unburned watersheds in the areas
affected by the Hayman, Hinman, and Missionary Ridge wildfires to provide
information to scientists, watershed managers, and public-water suppliers
regarding the extent to which wildfires may cause water-quality degradation.
Purpose
The purpose of this report is to present the postfire water– quality
data collected from streams draining watersheds burned by Colorado wildfires
in 2002.
Description of the Study Areas
Water-quality sampling was done in watersheds affected by the
following fires:
1. The Hayman fire occurred approximately 40 mi southeast of the Denver
Metropolitan area in mid-elevation Ponderosa and Douglas Fir forests on
highly weathered Pikes Peak granite (fig. 1). The Hayman burn area affects
a major portion of Denver’s raw water supply. No substantial prefire
USGS data are available. Two small watersheds were selected for a water-quality
comparison of a site not affected by the wildfire (Pine Creek) and a site
affected by the wildfire (Fourmile Creek).
2. The Hinman fire occurred approximately 20 mi north of Steamboat Springs
in high-elevation coniferous forest on crystalline, sedimentary, and metamorphic
rock types (fig. 1). Prefire USGS water-quality data are available for
1999 and 2000 along the North Fork of the Elk River and selected tributaries
(Leib and von Guerard, 2002). These data were collected after a 1998 blowdown
in that area of the Zirkel Mountains. Two sites were selected downstream
from burned watersheds that had preexisting water-quality data available
to facilitate a prefire/postfire comparison of water quality. Lost Dog
Creek is a small, 3.2 mi2 watershed that was severely burned and represents
upland runoff conditions. North Fork of the Elk River is a larger 41.4
mi2 watershed that integrates many different areas affected to various
degrees by the fire.
3. The Missionary Ridge fire occurred approximately 10 mi northeast of
Durango, Colorado in high-elevation coniferous forest on igneous and sedimentary
rock types (fig. 1). The Missionary Ridge fire burned portions of the
watersheds of Vallecito Reservoir, Lemon Reservoir, and the Animas River.
These water bodies serve as a portion of the water supply for the city
of Durango, the city of Bayfield, and the Southern Ute Indian Tribe. Prefire
USGS water-quality data are available for 1996, 1997, and 2000-2002 for
Vallecito Reservoir, its two major inlets, and its outlet. Postfire water–quality
data in the Vallecito Reservoir watershed were collected from the same
sites as the prefire water–quality data. In the Lemon Reservoir
watershed postfire water quality data were collected from the major inlet
to Lemon Reservoir (above the burn area), Lemon Reservoir (adjacent to
the burn area), and two sites downstream from the reservoir (below the
burn area).
Data and Methods
The major ion, metals, sediment, dissolved organic carbon, and ultra violet
absorbance data are presented in table 1. The concentrations of targeted
organic compounds are presented in table 2. These compounds are those
known to form or thought highly likely to form during a fire. A list of
tentatively identified organic compounds is presented in table 3. Tentatively
identified compounds are those compounds that were identified by matching
the mass chromatogram of a sample with mass chromatograms in an electronic
mass spectral library. The difference between the targeted and tentatively
identified organic compounds is as follows. For the targeted organic compounds,
the mass spectrometer was calibrated for these compounds and a quantitative
measurement of the concentration of each compound was possible. For the
tentatively identified organic compounds, the mass spectrometer was not
calibrated for any organic compound so this was a qualitative assessment
rather than a quantitative one. In other words, it was possible to determine
if a certain organic compound was present but its concentration could
not be accurately measured. Results of limited samples collected for the
purpose of running a trihalomethane (THM) formation potential test are
listed in table 4. Figure 1, tables 1 through 4, and a page explaining
abbreviations and acronyms are at the back of this report. The methods
used for the analyses of all the constituents listed in tables 1–4
can be found in Fishman (1993). The methods used for the collection of
the water–quality samples can be found in the USGS National Field
Manual for the collection of water–quality data. The methods used
for the THM analysis can be found in Crepeau and others (2004).
References
Crepeau, K.L., Fram, M., and Bush, N., 2004, Method of analysis
by the U.S. Geological Survey California District Sacramento
Laboratory—Determination of Trihalomethane Formation
Potential, Method Validation, and Quality-Control Practices: U.S. Geological
Survey Scientific Investigations Report 33 p.
Fishman, M.J., 1993, Methods of analysis by the U.S.
Geological
Survey National Water Quality Laboratory; determinations
of inorganic and organic constituents in water and fluvial
sediments: U.S. Geological Survey Open-File Report 93-125, 217 p.
Leib, K.J., and von Guerard, Paul, 2002, Data Summary
and Loading Sources for Selected Water–Quality Characteristics of
Streams in Blowdown Areas, North Fork Elk River Watershed,
Colorado, March 1999–August 2000: U.S. Geological Survey Fact Sheet
127–02, 4 p.
U.S. Geological Survey, variously dated, National field
manual for the collection of water-quality data: U.S. Geological Survey
Techniques of Water-Resources Investigations, book 9, chaps. A1-A9, available
online at https://pubs.water.usgs.gov/twri9A.
Contents
Problem
Purpose of Study
Description of the Study Areas
Data and Methods
References
Data Section
Figures
1. Map showing location
Tables (in the Data Section)
(available in Excel format)
1. Concentrations of major
ion
2. Concentrations of target
organic compounds found in samples collected at selected sites
3. Tentatively identified
organic compounds detected in water samples and bed-sediment samples for
selected sites
4. Trihalomethane formation
(THM) potential data from selected sites
5. Concentrations of trace elements
detected in bed-sediment samples for selected sites
5. Concentrations of trace
elements detected in bed-sediment samples for selected sites
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