United States
Environmental Protection
Agency
Municipal Environmental Research -_
Laboratory
Cincinnati OH 45268
SEPA
Research and Development
EPA-600/S2-82-090 Dec. 1982
Project Summary
Sources of Urban Runoff
Pollution and Its Effects on an
Urban Creek
Robert Pitt and Martin Bozeman
Sources and impacts of urban runoff
were studied for the Coyote Creek
near San Jose, California. The 3-year
monitoring study included three tasks:
(1) identifying and describing
important sources of urban runoff
pollutants; (2) describing the effects
of those pollutants on water and
sediment quality, aquatic organisms,
and associated beneficial uses of the
creek; and (3) assessing potential
measures for controlling the problem
pollutants in urban runoff.
Results indicated that various urban
runoff constituents (especially
organics and heavy metals) may be
responsible for many of the adverse
biological conditions observed in
Coyote Creek. But adequate control of
pollutants would require extremely
high removals that would be difficult
as well as costly to achieve.
This Project Summary was developed
by EPA's Municipal Environmental
Research Laboratory, Cincinnati. OH,
to announce key findings of the
research project that is fully
documented in a separate report of the
same title (see Project Report order-
ing information at back).
Introduction
A 3-year monitoring study was
conducted to evaluate the sources and
impacts of urban runoff on water quality
and biological conditions in Coyote
Creek near San Jose, California. The
three major elements of this study
included: (1) identifying and describing
important sources of urban runoff
pollutants; (2) describing the effects of
those pollutants on water and sediment
quality, aquatic organisms, and associ-
ated beneficial uses of the creek; and (3)
assessing potential measures for
controlling the problem pollutants in
urban runoff. In many cases, very
pronounced gradients of water and
biological quality indicators were
observed. Though cause-and-effect
relationships cannot be conclusively
proved in a study such as this, the
degraded conditions in Coyote Creek
may be the results of several factors,
including urban runoff, stream flows,
(associated or not with urban runoff),
and natural conditions such as drought,
stream gradient, groundwater
infiltration, etc. Information developed
during this study implies that various
urban runoff constituents (especially
organics and heavy metals in the water
and polluted sediment) may be
responsible for many of the adverse
biological conditions observed.
Site Description
The Coyote Creek watershed (Figure
1) is near San Jose, California. Coyote
Creek is a small stream, about 130 km
(80 mi) long, originating in a wilderness
area that is virtually free of pollutant
sources. The upper reaches and
headwaters of Coyote Creek have
extremely rugged, chaparral-covered
terrain with slopes commonly exceeding
30 percent. Much of this land is within
the Henry Coe State Park; nonpark land
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v Oakland
San1
Fran-
cisco^ Sari
Francisco\ Hayward
Bay
Pacific Ocean
Figure 1. Location of the Coyote Creek watershed in relation to
the San Francisco Bay Area.
0 5 10 15
miles
Q 5 10152025
kilometers
is used primarily for low-intensity cattle
grazing. The Coyote Creek watershed is
about 70 km (45 mi) long and 15 km (10
mi) wide, and it contains about 80,000
ha (200,000 acres). About 15 percent of
the watershed (all in the downstream
reach) consists of parts of the San Jose
urban area. The upstream waters pass
through two manmade flood control
reservoirs (Coyote Lake and Lake
Anderson) that control the creek flow
during most of the year. The lower
reaches of the watershed are in broad
plain. Most of the 24-mile-long study
area was located between Lake
Anderson in the nonurban area and the
first major creek confluence within the
city of San Jose (where Coyote Creek
meets Silver Creek).
Field Program
In this study, water quality, sediment,
and biological characteristics of the
creek were measured in the urban and
nonurban reaches of Coyote Creek.
Differences in these characteristics
were evaluated to quantify any
degradation and to identify the pollutant
sources. Early in the study (spring of
1977), a pilot water quality survey was
conducted along Coyote Creek from
Anderson Dam to San Francisco Bay.
Water quality samples were obtained at
10 sites and analyzed for major constit-
uents. The full-scale sampling program
was designed and carried out after this
pilot survey was completed.
The beginning of the 3-year
monitoring project followed 2 years of
severe drought, during which precipi-
tation was only about half its normal
average. Normal rains are about 33
cm/yr (13 in./yr) in the area below Lake
Anderson and 50 to 70 cm (20 to 28 in.)
in the watershed above Lake Anderson.
The first major rains ending the drought
occurred in November 1977, and rains
during the study period were close to
normal. Typical summer flows in the
urbanized creek sections were less than
1.5 mVs (53 ftVs).
During the field program, 41 stations
were sampled in both urban and
nonurban perennial flow stretches of
the creek. Short- and long-term samp-
ling techniques were used to evaluate
the effects of urban runoff on water
quality, sediment properties, fish,
macroinvertebrates, attached algae,
and rooted aquatic vegetation. The
program was designed to define
receiving water conditions in the urban
and nonurban areas during dry weather
conditions.
Sampling Methods
Creek flow rates were either
measured by the field personnel using a
digital current meter, or they were
estimated with floats. All stream
sampling on this project was conducted
manually with submerged, plastic,
wide-mouthed bottles. The samples
were preserved and analyzed according
to the requirements of the U.S.
Environmental Protection Agency
(EPA).
Sediment samples were obtained by
scooping bottom material into glass jars
and sealing the containers underwater.
The samples were then frozen and
delivered to the laboratory for EPA-
approved analyses. Sediment core
samples (for examining stratification)
were obtained with a liquid carbon
dioxide freezing core sampler.
Biological samples (mosquitofish,
filamentous algae, crayfish, and cattail
plant segment) were obtained at
selected sampling stations and were
chemically digested and analyzed for
total lead and zinc concentrations.
Fish were collected by seining and
electroshocking representative pool and
riffle habitats. Captured fish were
identified and counted. The total length
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and weight were recorded for each
specimen. Where numerous individuals
of a particular species were encoun-
tered, only length range and aggregate
weight were recorded.
Replicate benthic macroinvertebrate
samples were collected from natural
substrates (e.g., cobbles, gravel, sand)
in both pool and riffle habitats by means
of an Ekman dredge or a Surber
sampler. Also used were replicate pairs
of artificial substrate samplers (Hester-
Dendy) constructed of multiple, parallel
plates of Masonite.* These samplers
were left in the stream for 8 weeks and
then removed and examined in the
laboratory.
Qualitative benthic collections were
also made with the use of a D-frame
sweep net. The benthic samples were
washed through a sieve with a mesh
size of 500 /urn. Organisms retained on
the screen were removed, preserved,
identified to the lowest possible taxon,
and enumerated.
Attached algae samples were
obtained from both natural and artificial
substrates throughout the various
reaches of Coyote Creek. Qualitative
samples of attached algae were
collected by scraping uniform areas of
natural substrates such as logs and
rocks. Qualitative collections of
attached algae were made with the use
of artificial substrates consisting of
diatometers equipped with glass slides.
These were suspended in the water
column for 8 weeks and then removed
and examined in the laboratory. The
qualitative samples were preserved and
identified. The quantitative samples
were prepared, identified, and enumer-
ated using the proportional count
method.
Rooted aquatic plants were sampled
qualitatively whenever they were
encountered in the study area. Plant
specimens were collected, pressed or
preserved, and identified.
Sources of Runoff Pollutants
Urban runoff studies must determine
how much of the total pollutant yield
observed at the watershed outfall is
attributable to each source. Sources far
from the inlet to the storm sewerage
system require overland flow. Accord-
ingly, they contribute relatively small
amounts of pollutants (based on
observations at the outfall). Conversely,
parking lots or street surfaces are
•Mention of trade names or commercial products
does not constitute endorsement or recommend-
ation for use.
impervious to water and are typically
located adjacent to the storm sewer
inlets. Hence the pollutants from these
areas contribute most to the outfall
yield.
One important project phase
examined potential sources of
pollutants. Runoff samples and dry
particulate samples were collected from
various source areas in San Jose,
including roofs, parking areas, and
gutters. Rainfall samples and outfall
samples were also analyzed. Rain was
found to have the lowest pollutant con-
centrations, whereas the parking lot
and gutter flows had the highest levels
(for most of the constituents studied).
Puddles in a city park were found to
have much greater specific
conductance and concentrations of total
solids and nitrates than any other
samples. The observed lead concen-
trations ranged widely, from less than
0.01 for the rain to more than 1.0 mg/L
for gutter flows.
Particulate samples from the San
Jose area had typically greater pollutant
concentrations than the corresponding
levels in local soils. Most constituent
levels increased with the degree of
urbanization. Rooftops are thought to
contribute the least pollutants. Parking
lots, street surfaces, and sidewalks are
expected to contribute most of the heavy
metals and bacteria, and some nutrients
to the total runoff yield. Landscaped
areas and vacant lots contribute most of
the solids, oxygen-demanding materials,
and other nutrients.
The amount and character of runoff-
borne pollutants from a given site
depend on factors such as the volume of
the storm event and the length of the
antecedent dry period (i.e., the period of
pollutant accumulation). Large storms
(those with high intensities and/or
large rainfall volumes) result in
contributions from impervious areas
(street surfaces and other paved areas)
that are small relative to the total runoff
particulate yield. This pattern is more
pronounced when the antecedent dry
periods are short. During such
conditions, the paved surfaces stay
relatively clean because of the frequent
rains. A large rainfall will result in sig-
nificant erosion from the surrounding
saturated pervious areas, however.
Thus areas with moderate rainfall
intensities and long periods of
accumulation (i.e., dirty paved surfaces
and dry surrounding soil conditions)
would have most of their urban runoff
output associated with pavement
washoff.
Of the total solids deposited in an
urban area, only about a third would
ever reach the outfall. And only about
10 percent of the nutrients and oxygen-
demanding materials deposited might
affect the receiving water quality. But
most of the heavy metals deposited in
the area would affect the receiving
waters. The remaining deposited
pollutants that are washed off the
source areas but do not reach the outfall
would accumulate in other areas of the
urban environment. The most signifi-
cant of such pollutant sinks in the urban
area are probably soils, groundwater,
plants, and animals.
Coyote Creek Water Quality
The purpose of the water quality
monitoring program on Coyote Creek
was to define receiving water
conditions in the urban and nonurban
areas during dry weather. Dry weather
conditions were studied because they
reflect long-term water quality charac-
teristics in the creek and are less
influenced by any specific urban runoff
event. Data on wet-weather water
quality conditions were obtained from
previous studies.
Dry-weather concentrations of many
constituents exceeded the expected
wet-weather concentrations by factors
of 2 to 5. For example, during dry
weather, concentrations of many of the
major constituents (e.g., major ions,
total solids, etc.) were significantly
greater in both the urban and nonurban
reaches. These constituents were all
found in substantially lower concentra-
tions in the urban runoff and in the rain.
The rain and the resulting runoff
apparently diluted the concentrations
off these constituents in the creek
during wet weather. Within the urban
area, many constituents were found in
greater concentrations during wet
weather than during dry weather—
COD, organic nitrogen, and especially
heavy metals such as lead, zinc, copper,
cadmium, mercury, iron, and nickel.
Similar differences between wet and
dry weather were also noted for the
nonurban areas, but the wet weather
concentrations were typically much
higher in the urban than in the
nonurban area.
Values for dry-weather samples
obtained from the urban and nonurban
reaches of Coyote Creek were
summarized in Table 1. Lead concentra-
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tions were more than seven times
greater in the urban reach than in the
nonurban reach during dry weather,
with a confidence level of 75 percent.
Other significant increases in urban
area concentrations occurred for
nitrogen, chloride, orthophosphate,
COD, specific conductance, sulfate, and
zinc. The dissolved oxygen measure-
ments were about 20 percent less in the
urban reach than in the nonurban reach
of the creek.
Lead concentrations exceeded the
water quality criteria for both livestock
and aquatic life. During dry weather, the
water was also hard to very hard
(typical of Santa Clara County surface
and ground waters). Chloride concen-
trations at the furthest downstream
station (Dixon) were high because of
tidal influences that caused mixing with
San Francisco Bay water. About half of
the observed ammonia values were
equal to or greater than the established
criteria for aquatic life (0.02 mg/L).
Total coliform bacteria populations
were also high at most of the sampling
sites. Water quality upstream of the
urbanized area was fairly consistent
from site to site, but the quality changed
markedly as the creek passed through
the urbanized area.
Selected wet-weather samples were
also analyzed for priority pollutants as a
special part of this study.
Coyote Creek Sediment Quality
Coyote Creek sediment quality is
summarized in Table 2. Lead concentra-
tions in the urban area sediments were
greater than those from the nonurban
area by a factor of about 6, which is the
widest margin for any constituent
monitoring. Large differences were also
found between the urban and nonurban
area data for both sulfate and phos-
phate. Average zinc concentrations in
the urban sediments were about 1.5
times those of nonurban sediments, but
with a high degree of confidence.
During the first survey, the
differences between urban and
nonurban sediment concentrations
were much greater: sulfur, lead, and
arsenic levels were 4 to 60 times
greater in urban area sediments. Sea-
sonal and yearly changes in relative
sediment concentrations can therefore
be significant.
Selected sediment samples were also
analyzed for many elements using mass
spectrographic procedures. Other
sediment samples were also analyzed
for priority pollutants.
The ratio of sediment concentrations
(mg/kg) to water concentrations
(mg/L) was also calculated. This
sediment-to-water ratio (S/W) would
be low for readily soluble constituents.
and it would be high for relatively
insoluble constituents. The S/W ratios
Table 1. Summary of Coyote Creek Water Quality Conditions in Dry Weather
Nonurban Area Stations
Below Anderson Dam (mg/l)
Urban Area Stations
Above Silver Creek (mg/l)
Parameter
Mean
Min
Max
Mean
Min
Max
Urban/'Nonurban
Differences
Ratio* % Confidence f
Total solids
Chloride
Dissolved oxygen
COD
Total phosphate
Total Kjedahl nitrogen
Lead
Zinc
270
<20
8.6
17
<0.2
<0.3
<0.005
0.019
244
<20
6.5
12
<0.02
<0.05
0.001
0.019
299
<20
10.6
23
0.59
0.50
0.002
0.019
590
43
6.8
30
0.25
0.45
0.036
0.033
280
30
1.5
19
<0.02
<0.05
0.003
0.010
1200
60
11.0
53
0.54
0.78
0.10
0.075
2.2
>2.2
0.8
1.8
>1.3
>1.7
>7
1.7
98
98
>99
98
65
85
75
80
* Ratio of urban to nonurban mean values.
t Percent confidence that urban does not equal nonurban values.
Table 2. Summary of Coyote Creek Sediment Quality Conditions
Nonurban Area Stations
Below Anderson Dam (mg/kg)*
Urban Area Stations
Above Silver Creek (mg/kg)
Parameter
Mean
Min
Max
Mean
Min
Max
Urban/'Nonurban
Differences
Ratio} % Confidence^
COD
Total phosphate
Total Kjeldahl nitrogen
Lead
Zinc
Median particle size (u)
35,500
148
6,500
18.8
64
4,350
7,400
7.5
138
6.7
14
210
98,000
344
29.000
37
90
8.760
39.300
168
2.490
114
96
4,480
4,600
14
146
20
30
70
131.000
406
14.000
400
170
8.600
1.1
1.1
0.4
6.1
1.5
1.0
<60
<60
85
96
97
<60
* Units are in milligrams of constituent per kilogram of total solids, except for the median particle size, which is measured in microns.
t Ratio of urban to nonurban mean values.
I Percent confidence that urban does not equal nonurban mean values..
4
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were found to be very high for most of
the constituents monitored. The largest
difference between urban and
nonurban S/W ratios was for lead,
where the S/W ratio was more than
3,000 for the urban area and only about
400 for the nonurban area. The total
Kjeldahl nitrogen S/W ratio was about
5,500 for the urban area, but it
exceeded 22,000 for the nonurban area.
For the other constituents studied, the
S/W ratios for urban and nonurban
areas were much closer. Urban runoff
constituents could be present in the
creek water column at acceptable
concentrations even when interstitial
waters in the sediments were polluted.
Unfortunately, little information is
available concerning the effects of
polluted sediments on benthic
organisms.
Effects of Pollutants on
Aquatic Organisms in
Coyote Creek
Bioaccumulation of Lead and
Zinc in Selected Coyote Creek
Organisms
Some evidence of bioaccumulation of
lead and zinc was found in many of the
samples of algae, crayfish, and cattails.
The measured metal concentrations in
the organisms exceeded those in the
sediments by a maximum factor of
about six. Concentrations of lead and
zinc in the organisms exceeded water
column concentrations by factors of 100
to 500. Lead concentrations in urban
area samples of algae, crayfish, and
cattails were two to three times as high
as those in nonurban samples, and zinc
levels in urban algae and cattails were
about three times as high as those of
nonurban samples. Lead and zinc con-
centrations in fish tissues were not
noticeably different in urban and non-
urban samples.
Species of Fish Found in
Coyote Creek
The relative abundance of fish
species observed in the urban and
nonurban reaches of Coyote Creek is
shown in Table 3. Introduced fish often
cause radical changes in the nature of
the fish fauna present in a given water
body. Often they become the dominant
fish because of a superior ability to
compete with the native species for food
or space, or because of a greater
tolerance to environmental stress.
Introduced species are generally most
abundant in aquatic habitats modified
by man, whereas native fish tend to
persist mostly in undisturbed areas.
Table 3.
Relative Abundance of Fish Species Collected from Coyote Creek
Between Anderson Dam and Silver Creek
Nonurbanized
Reach
Urbanized
Reach
Species
Native fish:
Hitch
Threespine stickleback
Sacramento sucker
Prickly sculpin
Sacramento blackfish
California roach
Introduced fish:
Mosquitofish
Fathead minnow
Threadfin shad
Green sunfish
Bluegill
Largemouth bass
White crappie
Black crappie
Goldfish
Carp
Golden shiner
Total number of fish collected
34.8
27.3
12.6
8.2
4.3
1.8
5.6
0.6
0.2
0.1
0.1
0.1
3.5
0.9
2,379
4.9
0.8
0.1
0.1
1.0
0.3
66.9
20.6
2.4
1.2
1.0
0.4
0.3
0.1
2.899
Such is apparently the case within
Coyote Creek.
Samples from the nonurban portion
of the study area were dominated by an
assemblage of native fish species such
as hitch, threespine stickleback,
Sacramento sucker, and prickly sculpin.
Rainbow trout, riffle sculpin, and
Sacramento squawfish were captured
only in the headwater reaches and
tributary streams of Coyote Creek.
Collectively, native species constituted
89 percent of the number and 79
percent of the biomass of the 2,379 fish
collected from the upper reaches of the
study area. By contrast, native species
accounted for only 7 percent of the
number and 31 percent of the biomass
of the 2,899 fish collected from the
urban reach of the study area.
Hitch was the most numerous native
fish species present. Hitch generally
exhibit a preference for quiet water
habitat and are characteristic of warm,
low elevation lakes, sloughs, sluggish
rivers, and ponds. Mosquitofish
dominated the collections from the
urbanized section of the creek and
accounted for more than two-thirds of
the total number of fish collected from
that area. This fish is particularly well
adapted to withstand extreme
environmental conditions, including
those imposed by stagnant waters with
low dissolved oxygen concentrations
and elevated temperatures. The second
most abundant fish species in the
urbanized reach of Coyote Creek, the
fathead minnow, is equally well
suited to tolerating extreme
environmental conditions. The species
can withstand low dissolved oxygen,
high temperature, high organic
pollution, and high alkalinities. Often
thriving in unstable environments such
as intermittent streams, the fathead
minnow can survive in a wide variety of
habitats.
Benthic Macroinvertebrates
Observed in Coyote Creek
The abundance and diversity of taxa
generally appear to be greatest in
nonurbanized sections of the stream
(Figure 2). The overall increase in
number and diversity of benthic
organisms encountered in the 1979
samples as compared with the 1978
samples may be attributed to further
recovery from the drought conditions
that preceded this study. The benthos in
the upper reaches of the creek consisted
primarily of amphipods and a diverse
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30-
25-
20-
I
10-\
5-
. 1978 Samples
1979 Samples
Urbanized
Nonurbanized
Q>
I
!
«
CO
I
CO
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follows: lead, 75 to 98 percent; zinc, 35
to 50 percent; suspended and settleable
solids, 40 to 90 percent; and oxygen-
demanding materials (e.g.,COD, BOD,
total organic carbon) and phosphate,
about 85 percent. Depending on the
location of acceptable biological
conditions, total urban runoff control
would have to be more than 80 percent
effective. These removal goals are all
very high and would be difficult to meet.
The full report was submitted in
fulfillment of Grant No. R-805418 by
Woodward-Clyde Consultants under
the sponsorship of the U.S.
Environmental Protection Agency.
Robert Pitt is a private consultant. Blue Mounds, Wl 53517; and Martin
Bozeman is with Woodward-Clyde Consultants, San Francisco, CA 94111.
Richard Field is the EPA Project Officer (see below).
The complete report, entitled "Sources of Urban Runoff Pollution and Its Effects
on an Urban Creek," (Order No. PB 83-111 021; Cost: $16.00, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Storm and Combined Sewer Section
Municipal Environmental Research Laboratory—Cincinnati
U.S. Environmental Protect/on Agency
Edison, NJ 08837
U. S. GOVERNMENT PRINTING OFFICE: 1983/659-095/557
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Environmental Protection
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