9342

• UCREFRP Catalog Number: 9342
• Author: Wynn, K. H., N. J. Bauch and N. E. Driver.
• Title: Gore Creek Watershed, Colorado--Assessment of Historical and Current Water Quantitiy, Water Quality, and Aquatic Ecology, 1968-98.
• USFW Year: 2001.
• USFW - Doc Type: Denver.
• Copyright Material: NO

Differences in macro invertebrate-
community structure were found among sites
in Gore Creek by evaluating changes in relative
abundance, total abundance, and dominant func-
tional feeding groups of the major macroinverte-
brate groups. Ephemeroptera (mayflies),
Plecoptera (stoneflies), Trichoptera (caddisflies),
and Coleoptera (beetles) exhibited relatively low
tolerance to water-quality degradation when
compared with Diptera (midges) and non-insects
(sludge worms). More than 80 percent ofthe
macroinvertebrate community at sites located
farthest upstream was composed of mayflies,
stoneflies, and caddisflies, indicating favorable
water-quality and habitat conditions. The relative
percentages of midges and sludge worms greatly
increased in the downstream reaches of Gore
Creek, which drain relatively larger areas of
urban and recreation land uses, indicating the
occurrence of nutrient and organic enrichment
in Gore Creek.
The macroinvertebrate community in Black
Gore Creek indicated adverse effects from sedi-
ment deposition. Macroinvertebrate abundance
was considerably reduced at the two sites where
streambed sediment was more prevalent; however,
differences in abundance also may have been
related to differences in habitat and availability
of food resources.
The lower 4 miles of Gore Creek, down-
stream from Red Sandstone Creek, have been
designated a Gold Medal fishery in recognition of
the high recreational value of the abundant brown
trout community. Gore Creek contained twice as
many trout as a reference site with similar habitat
characteristics in Rocky Mountain National Park.
Moderate increases in nutrient concentra-
tions above background conditions have increased
the growth and abundance potential for aquatic
life in Gore Creek, while at the same time,
esthetic and water-quality conditions have
remained favorable. The spatial distribution of
nitrate concentrations was consistent with the
observed spatial distribution of algal biomass
and macroinvertebrate-community characteristics.
Algal biomass was limited by available resources
(sunlight and nutrients) in the upstream reaches

of Gore Creek and limited by macroinvertebrate
grazing and water-quality conditions in the down-
stream reaches. The fish community has benefited
from enhanced biological production in the
downstream reach of Gore Creek. Increases in
algal biomass and macroinvertebrate abundance,
in response to higher nutrient concentrations,
provide ample food resources necessary to
support the abundant fish community.
Trace-element data for surface water,
ground water, streambed sediment, fish tissue,
and macroinvertebrate tissue indicate that
concentrations are generally low in the Gore
Creek watershed. In streambed-sediment samples,
cadmium, copper, and zinc concentrations were
below background levels reported for the Upper
Colorado River Basin in Colorado. Concentra-
tions of cadmium, copper, iron, and silver in
surface water have occasionally exceeded stream
standards in the past, but recent surface-water data
indicate these trace elements currently are not of
concern. Manganese concentrations commonly
exceeded the 50-microgram-per-liter stream stan-
dard in Black Gore Creek. Elevated manganese
concentrations were primarily attributable to the
sedimentary geology of the area.
Concentrations of organic constituents are
low in the Gore Creek watershed. Pesticides were
detected infrequently and at low concentrations
in surface-water, ground-water, bed-sediment, and
whole-body fish-tissue samples. Volatile organic
compounds also were detected at low concentra-
tions in surface- and ground-water samples.

INTRODUCTION

Gore Creek, which drains an area of about
102 mi2, flows about 19 miles, from an area along
the Gore Range through the Town of Vail, joining
the Eagle River near Vail in Eagle County, Colorado
(fig. 1). Development in the Gore Creek watershed
has the potential to detrimentally affect the water
quality in Gore Creek and its tributaries. To manage
water resources, local entities are interested in better
understanding water quality and its relation to land
uses and natural factors in the Gore Creek watershed.
In response to these concerns, the Town of Vail,

2 Gore Creek Watershed, Colorado-Assessment of Historical and Current Water Quantity, Water Quality,
and Aquatic Ecology, 1968-98