&ER&
United States
Environmental Protection
Agency
Environmental Research
Laboratory
Corvallis OR 97330
Research and Development
EPA-600/S3-81-033 July 1981
Project Summary
Oxygen-Consuming Organics
in Nonpoint Source Runoff
A. Ray Abernathy
The Project Report which is
summarized here presents the results
of a comprehensive survey and review
of recent literature, especially EPA
Research Reports, relating to
nonpoint source (NPS) runoff. It
summarizes the findings on loadings
of oxygen-consuming materials
discharged to freshwater nonpoint
source runoff and is an attempt to
synthesize the more significant
findings on the oxygen demand of
both urban and rural nonpoint
sources. It also attempts to estimate
the impact of these loadings upon the
dissolved oxygen resources of
freshwater systems and the ecological
effects upon freshwater environments.
Emphasis has been placed upon urban
sources of NPS biodegradable
organics; rural sources of NPS
biodegradable organics; the impact of
NPS constituents upon stream
dissolved oxygen (DO); and the effects
of DO depletion upon fish, both
salmonid and non-salmonid.
The literature shows that there is a
serious shortage of data on surface
accumulation rates, stream-side
loading rates, and DO concentrations
resulting from nonpoint sources
inputs - all measured concurrently
within the same watershed. The data
available indicate that the oxygen
demanding loadings from urban
runoff can be significant, but that
estimates of effects upon fish and
other aquatic organisms must await
more information.
This Project Summary was
developed by EPA's Environmental
Research Laboratory. Corvallis, OR, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
The report presents the results of a
comprehensive review of relatively
recent publications, especially EPA
reports, relating to nonpoint source
(NPS) runoff from both urban and rural
sources.
Urban runoff has been shown to
contain concentrations of biochemical
oxygen demand (BOD), suspended
solids, and coliform bacteria in as great
or greater concentrations than treated
sewage effluents, along with heavy
metals and other toxic materials. Street
dust, dirt, airborne particulates, and
other such debris contribute much of
the polluting material in urban runoff.
Research has shown that urban
runoff may contain suspended solids up
to 2,000 mg/l, chemical oxygen
demand (COD) as high as 1,000 mg/l,
total phosphorus as great as 15 mg/l,
and fecal coliforms up to several
thousand organisms per 100 ml. Heavy
metal concentrations are usually
greater than in untreated domestic
sewage.
Rural NPS runoff, on the other hand,
can include sediments, plant nutrients,
pesticides, organic matter, minerals and
* US GOVERNMENT PRINTING OFFICE. 1961 -757-012/7237
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microorganisms. Agricultural, silvicul-
tural, mining, and construction activi-
ties can be major sources of rural NPS
runoff.
Both urban and rural runoff have
been shown to contain oxygen-consum-
ing organic matter, a potenial pollution
problem addressed in the report. The
oxygen-demanding capacity of both
urban and rural NPS runoff are
characterized and the impact of the
resulting deoxygenation upon fish is
explored.
Conclusions
As a result of this literature review,
the following conclusions can be made:
1. Urban NPS runoff has been
shown to contain large quantities
of oxygen-demanding materials.
Although few direct measure-
ments have been made of the
oxygen demands actually exerted
in streams, modeling studies
have indicated that the DO
demand from urban NPS runoff
can result in low DO concentra-
tions, either alone or in combina-
tion with point source discharges.
2. It is more difficult to show serious
oxygen depletion due to NPS
runoff from rural areas. More
serious rural NPS pollutants
seem to be sediments from soil
erosion, plant nutrients, and toxic
materials such as pesticides.
3. Continuous exposure to DO
concentrations significantly
lower than air saturation concen-
trations seems to be harmful to
fish, both salmonids and
warmwater species.
4. Exposure to fluctuating DO
concentrations between air
saturation and 60-65 percent of
saturation can reduce the growth
rate of fish if the high and low
concentration exposure periods
are approximately equal (12
hours each) during each day.
5. Efforts should be made to achieve
the appropriate DO standards by
reducing the loads of BOD in NPS
runoff as well as point source
discharges. Reduction of the BOD
loadings from NPS runoff should
result in other improvements in
receiving water quality by redi
ing the loadings of suspeno
solids, plant nutrients, a
potentially toxic materials.
6. Research should be carried out
directly relate stream impact
end-of-pipe loadings and surfa
accumulation of urban Nf
pollutants.
7. Research should be performed
evaluate the effects of or
exposure of 12 hours per week
DO concentrations of 2, 3, and
mg/l upon the growth rate off is
This Project Summary was authored by A. Ray Abernathy, who is also the EPA
Project Officer (see below).
The complete report, entitled "Oxygen-Consuming Organics in Nonpoint Source
Runoff: A Literature Review," (Order No. PB81-205 981; Cost: $6.50, subject
to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Research Laboratory
U.S. Environmental Protection Agency
Corvallis, OR 97330
United Stales
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
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Penalty for Private. Use S300
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