United States
Environmental Protection
Agency
Water Planning Division
WH-554
Washington, DC 20460
December 1983
Water
Results of the Nationwide
Urban Runoff Program
Executive Summary
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RESULTS
OF THE
NATIONWIDE URBAN RUNOFF PROGRAM
December, 1983
EXECUTIVE SUMMARY
Water Planning Division
U.S. Environmental Protection Agency
Washington, D.C. 20460
National Technical Information Service (NTIS)
Accession Number: PB84-185545
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DISCLAIMER
This report has been reviewed by the U.S. Environmental
Protection Agency and approved for release. Approval to
publish does not signify that the contents necessarily
reflect any policies or decisions of the U.S. Environmental
Protection Agency or any of its offices, grantees, con-
tractors, or subcontractors.
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ACKNOWLEDGEMENTS
The Nationwide Urban Runoff Program was unusual in its large scale, covering
a broad spectrum of technical and planning issues at many geographic loca-
tions. Because the program placed such emphasis on tailoring the results to
support the planning process, it involved many participants - some from EPA,
some from other federal agencies, and many from state, regional, and local
planning agencies and other consultants.
The program was developed, implemented, and managed by the Water Planning
Division, Office of Water, at EPA Headquarters, Washington, D.C. Principal
contributors were: Dennis N. Athayde, Program Manager; and Patrice M. Bubar,
Norman A. Whalen, Stuart S. Tuller, and Phillip H. Graham, all of whom served
as Project Officers. Additional contributions from EPA personnel came from
Rod E. Frederick and Richard P. Healy (Monitoring and Data Support Division),
Richard Field (Storm and Combined Sewer Section, EPA Office of Research and
Development), and many project staff in the various EPA Regional Offices.
As described elsewhere, much of the field work, water quality analysis, and
data analysis was performed by the U.S. Geological Survey (USGS), under a
Memorandum of Agreement with EPA. Both District Offices and National Head-
quarters participated actively. The contributions of Messrs. Ernest Cobb and
David Lystrom are especially acknowledged.
Members of the project team which provided essential strategic, technical,
and management assistance to the EPA Water Planning Division through a con-
tract with Woodward-Clyde Consultants were: Gail B. Boyd, David Gaboury,
Peter Mangarella, and James D. Sartor (Woodward-Clyde Consultants); Eugene D.
Driscoll (E. D. Driscoll and Associates); Philip E. Shelley (EG&G Washington
Analytical Services Center, Inc.); John L. Mancini (Mancini and DiToro Con-
sultants) ; Robert E. Pitt (private consultant); Alan Plummer (Alan Plummer
and Associates); and James P. Heaney and Wayne C. Huber (University of
Florida).
The principal writers of this report were Dennis N. Athayde (EPA),
Philip E. Shelley (EGSG Washington Analytical Services Center, Inc.),
Eugene D. Driscoll (E. D. Driscoll & Associates), and David Gaboury and
Gail B. Boyd (Woodward-Clyde Consultants).
111
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EXECUTIVE SUMMARY
BACKGROUND
The water quality effects of stormwater pollution received little attention
prior to 1960. Stormwater concerns were primarily related to drainage
problems. As stormwater pollution began to be investigated, the work,
reported by EPA and published in professional journals, tended to focus on
determining (a) the type and amount of pollutants involved and/or (b) methods
to reduce the loads. However, such reports and articles gave limited con-
sideration to either the level of improvement attainable or the need to
improve quality of the receiving water body associated with the study. A
conclusion common to all such reports was that not enough was known about
stormwater, and recommendations for further study and more data were the
norm. A tangible result of the uncertain attitude in this area is the fact
that stormwater controls for water quality have been implemented in so few
places throughout the nation. Thus, there has been a critical need to ob-
jectively examine the situation. This need led to the development of the
Nationwide Urban Runoff Program (NURP).
The overall goal of NURP was to develop information that would help provide
local decision makers, States, EPA, and other interested parties with a
rational basis for determining whether or not urban runoff is causing water
quality problems and, in the event that it is, for postulating realistic
control options and developing water quality management plans, consistent
with local needs, that would lead to implementation of least cost solutions.
It is also hoped that this information base will be used to help make the
best possible policy decision on Federal, State, and local involvement in
urban stormwater runoff and its control. Among the many objectives of NURP
was the assembly of an appropriate data base and the development of
analytical methodologies that would allow us to examine such issues as:
- The quality characteristics of urban runoff, and similarities or
differences at different urban locations;
The extent to which urban runoff is a significant contributor to
water quality problems across the nation; and
- The performance characteristics and the overall effectiveness
and utility of management practices for the control of pollutant
loads from urban runoff.
Water quantity problems are relatively easy to identify and describe. Water
quality problems, on the other hand, tend _o be more elusive because their
definition often involves some subjective considerations, including expe-
riential aspects and expectations of the populace. They are not immediately
obvious and are usually less dramatic than, for example, floods. They also
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tend to vary markedly with locality and geographic regions within the
country. Thus, a methodological approach to the determination of water
quality problems is essential if one is to consider the relative role of
urban runoff as a contributor. An important finding of the work conducted
during NURP was to learn to avoid the following simplistic logic train:
(a) water quality problems are caused by pollutants, (b) there are pollutants
in urban runoff, therefore, (c) urban runoff causes "problems". The unspoken
implication is that a "problem" by definition requires action, and any type
of "problem" warrants equally vigorous action. It becomes clear that a more
fundamental and more precise definition of a water quality "problem" from
urban runoff is necessary. For this purpose, NURP adopted the following
three-level definition:
Impairment or denial of beneficial uses;
- Water quality criterion violation; and
Local public perception.
The foregoing levels of problem definition provide an essential framework
within which to discuss water quality problems associated with urban runoff.
However, it is important to understand that when one is dealing at a local
level all three elements are typically present. Thus, it is up to the local
decision makers, influenced by other levels of support and concern, to care-
fully weigh each, prior to making a final decision about the existence and
extent of a problem and how it is to be defined.
The NURP studies have greatly increased our knowledge of the characteristics
of urban runoff, its effects upon designated uses, and of the performance
efficiencies of selected control measures. They have also confirmed earlier
impressions that some States and local communities have actually begun to
develop and implement stormwater management programs incorporating water
quality objectives. However, such management initiatives are, at present,
scattered and localized. The experience gained from such efforts is both
needed and sought after by many other States and localities. Documentation,
evaluation, refinement and transfer of management and financing mechanisms/
arrangements, of simple and reliable problem assessment methodologies, and of
implementation guidance which can be used by planners and officials at the
State and local level are urgently needed as is a forum for the sharing of
experiences by those already involved, both among themselves and with those
who are about to address nonpoint source issues.
CONCLUSIONS
The following summarizes NURP's conclusion relating to its major objectives
and is based on the results presented in Chapters 6, 7, and 8 of the report.
Conclusions reached by the individual NURP projects are also presented to
further support the results of the national level analysis.
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URBAN RUNOFF CHARACTERISTICS
General
Field monitoring was conducted to characterize urban runoff flows and pol-
lutant concentrations. This was done for a variety of pollutants at a sub-
stantial number of sites distributed throughout the country. The resultant
data represent a cross-section of regional climatology, land use types,
slopes, and soil conditions and thereby provide a basis for identifying pat-
terns of similarities or differences and testing their significance.
Urban runoff flows and concentrations of contaminants are quite variable.
Experience shows that substantial variations occur within a particular event
and from one event to the next at a particular site. Due to the high vari-
ability of urban runoff, a large number of sites and storm events were moni-
tored, and a statistical approach was used to analyze the data. Procedures
are available for characterizing variable data without requiring knowledge of
or existence of any underlying probability distribution (nonparametric
statistical procedures). However, where a specific type of probability dis-
tribution is known to exist, the information content and efficiency of sta-
tistical analysis is enhanced. Standard statistical procedures allowed
probability distributions or frequency of occurrence to be examined and
tested. Since the underlying distributions were determined to be adequately
represented by the lognormal distribution, the log (base e) transforms of all
urban runoff data were used in developing the statistical characterizations.
The event mean concentration (EMC), defined as the total constituent mass
discharge divided by the total runoff volume, was chosen as the primary water
quality statistic. Event mean concentrations were based on flow weighted
composite samples for each event at each site in the accessible data base.
EMCs were chosen as the primary water quality characteristic subjected to
detailed analysis, even though it is recognized that mass loading character-
istics of urban runoff (e.g., pounds/acre for a specified time interval) is
ultimately the relevant factor in many situations. The reason is that,
unlike EMCs, mass loadings are very strongly influenced by the amount of
precipitation and runoff, and estimates of typical annual mass loads will be
biased by the size of monitored storm events. The most reliable basis for
characterizing annual or seasonal mass loads is on the basis of EMC and
site-specific rainfall/runoff characteristics.
Establishing the fundamental distribution as lognormal and the availability
of a sufficiently large population of EMCs to provide reliability to the
statistics derived has yielded a number of benefits, including the ability to
provide:
Concise summaries of highly variable data
- Meaningful comparisons of results from different sites, events,
etc.
Statements concerning frequency of occurrence. One can express
how often values will be expected to exceed various magnitudes
of interest.
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A more useful method of reporting data than the use of ranges;
one which is less subject to misinterpretation
- A framework for examining "transferability" of data in a quanti-
tative manner
Conclusions
1. Heavy metals (especially copper, lead and zinc) are by far the most pre-
valent priority pollutant constituents found in urban runoff. End-of-pipe
concentrations exceed EPA ambient water quality criteria and drinking
water standards in many instances. Some of the metals are present often
enough and in high enough concentrations to be potential threats to bene-
ficial uses.
All 13 metals on EPA's priority pollutant list were detected in urban
runoff samples, and all but three at frequencies of detection greater
than 10 percent. Most often detected among the metals were copper, lead,
and zinc, all of which were found in at least 91 percent of the samples.
Metal concentrations in end-of-pipe urban runoff samples (i.e., before
dilution by receiving water) exceeded EPA's water quality criteria and
drinking water standards numerous times. For example, freshwater acute
criteria were exceeded by copper concentrations in 47 percent of the
samples and by lead in 23 percent. Freshwater chronic exceedances were
common for lead (94 percent), copper (82 percent), zinc (77 percent), and
cadmium (48 percent). Regarding human toxicity, the most significant
pollutants were lead and nickel, and for human carcinogenesis, arsenic
and beryllium. Lead concentrations violated drinking water criteria in
73 percent of the samples.
It should be stressed that the exceedances noted above do not necessarily
imply that an actual violation of standards will exist in the receiving
water body in question. Rather, the enumeration of exceedances serves a
screening function to identify those heavy metals whose presence in urban
runoff warrants high priority for further evaluation.
Based upon the much more extensive NURP data set for total copper, lead,
and zinc, the site median EMC values for the median urban site are: Cu =
34 yg/1, Pb = 144 yg/1, and Zn = 160 yg/1. For the 90th percentile urban
site the values are: Cu = 93 yg/1, Pb = 350 yg/1, and Zn = 500 yg/1.
These values are suggested to be appropriate for planning level screening
analyses where data are not available.
Some individual NURP project sites (e.g., at DC1, MD1, NH1) found unus-
ually high concentrations of certain heavy metals (especially copper and
zinc) in urban runoff. This was attributed by the projects to the effect
of acid rain on materials used for gutters, culverts, etc.
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2. The organic priority pollutants were detected less frequently and at
lower concentrations than the heavy metals.
Sixty-three of a possible 106 organics were detected in urban runoff
samples. The most commonly found organic was the plasticizer bis
(2-ethylhexl) phthalate (22 percent), followed by the pesticide
a-hexachlorocyclohexane (a-EHC) (20 percent). An additional 11 organic
pollutants were reported at frequencies between 10 and 20 percent;
3 pesticides, 3 phenols, 4 polycyclic aromatics, and a single halogenated
aliphatic.
Criteria exceedar.ces were less frequently observed among the organics
than the heavy metals. One unusually high pentachlorophenol concentra-
tion of 115 ug/1 resulted in exceedances of the freshwater acute and
organoleptic criteria. This observation and one for chlordane also ex-
ceeded the freshwater acute criteria. Freshwater chronic criteria ex-
ceedances were observed for pentachlorophenol, bis (2-ethylhexyl)
phthalate, gamma-BHC, chlordane, and alpha-endosulfan. All other organic
exceedances were in the human carcinogen category and were most serious
for alpha-hexachlorocyclohexane (alpha-BHC), gamma-hexachlorccyclohexane
(gairana-BHC or Lindane) , chlordane, phenanthrene, pyrene, and chrysene.
The fact that the NURP priority pollutant monitoring effort was limited
to two samples at each site leaves us unable to make many generalizations
about those organic pollutants which occurred only rarely. We can spec-
ulate that their occurrences tend to be very site specific as opposed to
being a generally widespread phenomena, but much more data would be re-
quired to conclusively prove this point.-
3. Coliform bacteria are present at high levels in urban runoff and can be
expected to exceed EPA water quality criteria during and immediately
after storm e'/ents in many surface waters, even those providing high
degrees of dilution.
Fecal coliform counts in urban runoff are typically in the tens to hun-
dreds of thousand per 100 ml during warm weather conditions, with the
median for all sites being around 21,000/100 ml. During cold weather,
fecal coliform counts are more typically in the 1,000/100 ml range, which
is the median for all sites. Thus, violations of fecal ccliform stand-
ards were reported by a number of NURP projects. High fecal colifcrm
counts may not cause actual use impairments, in some instances, due to
the location of the urban runoff discharges relative to swimming areas or
shellfish beds and the degree of dilution/dispersal and rate of die off.
The same is true of total coliform counts, which were found to exceed EPA
water quality criteria in undiluted urban runoff at virtually every site
every time it rained.
The substantial seasonal differences noted above do not correspond with
comparable variations in urban activities. The NURP analyses as well as
current literature suggest that fecal coliform may not be the most
appropriate indicator organism for identifying potential health risks
when the source is stormwater runoff.
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4. Nutrients are generally present inurban runoff,but with a few individ-
ual site exceptions,concentrations do not appear to be high _in compari-
son with other possible discharges to receiving water bodies.
NURP data for total phosphorus, soluble phosphorus, total kjeldahl nitro-
gen, and nitrate plus nitrite as nitrogen were carefully examined. Me-
dian site EMC median concentrations in urban runoff were TP = 0.33 mg/1,
SP = 0.12 mg/1, TKN = 1,5 mg/1, and NO2+3 - N = 0.68 mg/1. On an annual
load basis, comparison with typical monitoring data, literature values,
and design objectives for discharges from a well run secondary treatment
plant suggests that mean annual nutrient loads from urban runoff are
around an order of magnitude less than those from a POTW.
5. Oxygen demanding substances are present in urban runoff at concentrations
approximating those in_ se_condary treatment plant discharges. If dis-
sqlyed oxygen problems__are_ present in receiving waters of interest, con-
sideration of urban runoff controls as well as advanced waste treatment
appears to be warranted.
Urban runoff median site EMC median concentrations of 9 mg/1 BODS and
65 mg/1 COD are reflected in the NURP data, with 90th percentile site EMC
median values being 15 mg/1 BODS and 140 mg/1 COD, These concentrations
suggest that, on an annual load basis, urban runoff is comparable in mag-
nitude to secondary treatment plant discharges,
It can be argued that urban runoff is typically well oxygenated and
provides increased stream flow and, hence, in view of relatively long
travel times to the critical point, that dissolved oxygen problems
attributable solely to urban runoff should not be widespread occurrences.
No NURP project specifically identified a low DO condition resulting from
urban runoff. Nonetheless, there will be some situations where con-
sideration of urban runoff controls for oxygen demanding substances in an
overall water quality management strategy would seem appropriate.
6. Total suspended solids concentrations in urban runoff are^ fairly high in
comparison withtreatment plant discharges. Urban runoff control is
stronglyindicated_where water qualityproblems associated with TSS, in-
cluding build-up of contaminated sediments, exist.
There are no formal water quality criteria for TSS relating to either
human health or aquatic life. The nature of the suspended solids in
urban runoff is different from those in treatment plant discharges, being
higher in mineral and man-made products (e.g., tire and street surface
wear particles) and somewhat lower in organic particulates. Also, the
solids in urban runoff are more likely to have other contaminants
adsorbed onto them. Thus, they cannot be simply considered as benign,
nor do they only pose an aesthetic issue. NURP did not examine the
problem of contaminated sediment build-up due to urban runoff, but it
undeniably exists, at least at some locations.
The suspended solids in urban runoff can also exert deleterious physical
effects by sedimenting over egg deposition sites, smothering juveniles,
and altering benthic communities.
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On an annual load basis, suspended solids contributions from urban runoff
are around an order of magnitude or more greater than those from second-
ary treatment plants. Control of urban runoff, as opposed to advanced
waste treatment, should be considered where TSS-associated water quality
problems exist.
7. A summary characterization of urban runoff has been developed and is
believed to be appropriate for use in estimating urban runoff pollutant
discharges from sites wheremonitoringdata are scant or lacking, at
least for planning level purposes.
As a result of extensive examination, it was concluded that geographic
location, land use category (residential, commercial, industrial park, or
mixed), or other factors (e.g., slope, population density, precipitation
characteristics) appear to be of little utility in consistently explain-
ing overall site-to-site variability in urban runoff EMCs or predicting
the characteristics of urban runoff discharges from unmonitored sites.
Uncertainty in site urban runoff characteristics caused by high event-
to-event variability at most sites eclipsed any site-to-site variability
that might have been present. The finding that EMC values are essen-
tially not correlated with storm runoff volumes facilitates the transfer
of urban runoff characteristics to unmonitored sites. Although there
tend to be exceptions to any generalization, the suggested summary urban
runoff characteristics given in Table 6-17 of the report are recommended
for planning level purposes as the best estimates, lacking local informa-
tion to the contrary.
RECEIVING WATER EFFECTS
General
The effects of urban runoff on receiving water quality are highly site-
specific. They depend on the type, size, and hydrology of the water body;
the urban runoff quantity and quality characteristics; the designated bene-
ficial use; and the concentration levels of the specific pollutants that
affect that use.
The conclusions which follow are based on screening analyses performed by
NUKP, observations and conclusions drawn by individual NUKP projects that
examined receiving water effects in differing levels of detail and rigor, and
NURP's three levels of problem definition. Conclusions are organized on the
basis of water body type: rivers and streams, lakes, estuaries and embay-
ments, and groundwater aquifers. Site-specific exceptions should be
expected, but the statements presented are believed to provide an accurate
perspective on the general tendency of urban runoff to contribute signifi-
cantly to water quality problems.
Rivers and Streams
1. Frequent exceedances of heavy metals ambient water quality criteria for
freshwater aquatic life are produced by urban runoff.
The Denver NURP project found that in-stream concentrations of copper,
lead, zinc, and cadmium exceeded State ambient water quality standards
for the South Platte River during essentially all storm events.
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NURP screening analyses suggest that frequent exceedances of both EPA
24-hour and maximum water quality criteria for heavy metals should be
expected on a relatively general basis.
2, Although_ a significant number of probl_em situations could result from
heavy metals i_n__urba_n runoff, levels of freshwater aquatic life use
impairment suggested by the magnitude and frequency of ambient criteria
exceedances were not observed.
Based upon the magnitude and frequency of freshwater aquatic life ambient
criteria exceedances, one would expect to observe impairment of this
beneficial use in most streams that receive urban runoff discharges.
However, those NURP project studies which examined this issue did not
report significant use impairment problems associated with urban runoff.
The Bellevue, Washington NURP project concluded that toxic effects of
urban runoff pollutants did not appear to be a significant factor.
The Tampa, Florida NURP project conducted biological studies of the
impact of stormwater runoff upon the biological community of the
Hillsborough River. They conducted animal bioassay experiments on five
sensitive species in two samples of urban runoff from the Arctic Street
drainage basin. Thirty-two bioassay experiments were completed including
22 acute tests and 10 chronic tests. Neither sample of stormwater was
acutely toxic to test organisms. Long-term chronic experiments were
undertaken with two species and resulted in no significant effects attri-
butable to stormwater exposure.
NURP screening analyses suggest that the potential of urban runoff to
seriously impair this beneficial use will be strongly influenced by local
conditions and the frequency of occurrence of concentration levels which
produce toxic effects under the intermittent, short duration exposures
typically produced by urban runoff.
While the application of the screening analysis to the Bellevue and Tampa
situations supports the absence of a problem situation in these cases, it
also suggests that a significant number of problem situations should be
expected. Therefore, although not the general, ubiquitous problem situa-
tion that criteria exceedances would suggest, there are site-specific
situations in which urban runoff could be expected to cause significant
impairment of freshwater aquatic life uses.
Because of the inconsistency between criteria exceedances and observed
use impairments due to urban runoff, adaptation of current ambient
quality criteria to better reflect use impacts where pollutant exposures
are intermittent and of short duration appears to be a useful area for
further investigation.
3. Copper, lead and zinc appear to pose a significant threat to aquatic life
uses in some areas of the country. Copper is suggested to be the most
si gni ficant of the three.
Regional differences in surface water hardness, which has a strong influ-
ence on toxicity, in conjunction with regional variations in stream flow
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and rainfall result in significant differences in susceptibility to ad-
verse impacts around the nation.
The southern and southeastern regions of the country are the most sus-
ceptible to aquatic life effects due to heavy metals, with the northeast
also a sensitive area, although somewhat less so.
Copper is the major toxic metal in urban runoff, with lead and zinc also
prevalent but a problem in more restricted cases. Copper discharges in
urban runoff are, in all but the most favorable cases, a significant
threat to aquatic life uses in the southeast and southern regions of the
country. In the northeast, problems would be expected only in rather
unfavorable conditions (large urban area contribution and high site con-
centrations) . In the remainder of the country (and for the other metals)
problems would only be expected under quite unfavorable site conditions.
These statements are based on total metal concentrations.
4. Organic priority pollutants in urban runoff do not appear to pose a gen-
eral threat to freshwater aquatic life.
This conclusion is based on limited data on the frequency with which or-
ganics are found in urban runoff discharges and measured end-of-pipe con-
centrations relative to published toxic criteria. One unusually high
pentachlorophenol concentration of 115 yg/1 resulted in the only exceed-
ance of the organoleptic criteria. This observation and one for
chlordane exceeded the freshwater acute criteria. Freshwater
chronic criteria exceedances were observed for pentochlorophenol,
bis (2-ethylhexyl) phlhalate, y-hexachlorocyclohexane (lindane),
a-endosulfan, and chlordane.
5. The physical aspects of urban runoff, e.g., erosion and scour, can be a
significant cause of habitat disruption and can affect the type of
fishery present. However, this area was studied only incidentally by
several of the projects under the NURP program and more concentrated
study is necessary.
The Metropolitan Washington Council of Governments (MWCOG) NURP project
did an analysis of fish diversity in the Seneca Creek Watershed, 20 miles
northwest of Washington, D.C. In this study, specific changes in fishery
diversity were identified due to urbanization in some of the sub-
watersheds. Specifically, the number of fish species present are reduced
and the types of species present changed dramatically, e.g., environ-
mentally sensitive species were replaced with more tolerant species. For
example, the Blacknose Dace replaced the Mottled Sculpin. MWCOG con-
cluded that the changes in fish diversity were due to habitat deteriora-
tion caused by the physical aspects of urban runoff.
The Bellevue, Washington NURP project concluded that habitat changes
(streambed scour and sedimentation) had a more significant effect than
pollutant concentrations, for the changes produced by urbanization.
6. Several projects identified possible problems in the sediments because of
the build-up of priority pollutants contributed wholly or in part by
urban runoff. However, the NURP studies in this area were few in number
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and limited in scope, and the findings must be considered only indicative
of the need for further study, particularly as to long-term impacts.
The Denver NURP project found significant quantities of copper, lead,
zinc, and cadmium in river sediments. The Denver Regional Council of
Governments is concerned that during periods of continuous low flow, lead
may reach levels capable of adversely affecting fish.
The Milwaukee NURP project reported the observation of elevated levels of
heavy metals, particularly lead, in the sediments of a river receiving
urban runoff.
7. Coliform bacteria are present at high levels in urban runoff and can be
expected to exceed EPA water quality criteria during and immediately
after storm events in most rivers and streams.
Violations of the fecal coliform standard were reported by a number of
NURP projects. In some instances, high fecal coliform counts may not
cause actual use impairments due to the location of the urban runoff
discharge relative to swimming areas and the degree of dilution or dis-
persal and rate of die off.
Coliform bacteria are generally accepted to be a useful indicator of the
possible presence of human pathogens when the source of contamination is
sanitary sewage. However, no such relationship has been demonstrated for
urban runoff. Therefore, the use of coliforms as an indicator of human
health risk when the sole source of contamination is urban runoff, war-
rants further investigation.
8. Domestic water supply systems with intakes located on streams in close
proximity to urban runoff discharges are encouraged to check for priority
pollutants which have been detected in urban runoff, particularly those
in the organic category.
Sixty-three of a possible 106 organics were detected in urban runoff sam-
ples. The most commonly found organic was the plasticizer bis
(2-ethylhexl) phthalate (22 percent), followed by the pesticide
a-hexachlorocyclohexane (a-BHC) (20 percent). An additional 11 organic
pollutants were reported at frequencies between 10 and 20 percent;
3 pesticides, 3 phenols, 4 polycyclic aromatics, and a single halogenated
aliphatic.
Lakes
1. Nutrients in urban runoff may accelerate eutrophication problems and
severely limit recreational uses, especially in lakes. However, NURP's
lake projects indicate that the degree of beneficial use impairment
varies widely, as does the significance of the urban runoff component.
The Lake Quinsigamond NURP project in Massachusetts identified eutrophi-
cation as a major problem in the lake, with urban runoff being a prime
contributor of the critical nutrient phosphorus. Point source discharges
10
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to the lake have been eliminated almost entirely. However, in spite of
the abatement of point sources, survey data indicate that the lake has
shown little improvement over the abatement period. In particular, the
trophic status of the lake has shown no change, i.e., it is still
classified as late mesotrophic-early eutrophic. Substantial growth is
projected in the basin, and there is concern that Lake Quinsigamond will
become more eutrophic. A proposed water quality management plan for the
lake includes the objective of reducing urban runoff pollutant loads.
The Lake George NUKP project in New York State also identified increasing
eutrophication as a potential problem if current development trends con-
tinue. Lake George is not classified as eutrophic, but from 1974 to 1978
algae production in the lake increased logarithmically. Lake George is a
very long lake, and the limnological differences between the north and
south basins provide evidence of human impact. The more developed,
southern portion of the lake exhibits lower transparencies, lower hypo-
limnetic dissolved oxygen concentrations, higher phosphorus and chlor-
ophyll a_ concentrations, and a trend toward seasonal blooms of blue-green
algae. These differences in water quality indicators are associated with
higher levels of cultural activities (e.g., increased sources of phos-
phorus) in the southern portion of the lake's watershed, and continued
development will tend to accentuate the differences.
The Lake George NURP project estimated that urban runoff from developed
areas currently accounts for only 13.6 percent of the annual phosphorus
loadings to Lake George as a whole. In contrast, developed areas con-
tribute 28.9 percent of the annual phosphorus load to the NURP study
areas at the south end of the Lake. Since there are no point source
discharges, this phosphorus loading is due solely to urban runoff. These
data illustrate the significant impact of urbanization on phosphorus
loads.
The NURP screening analysis suggests that lakes for which the contribu-
tions of urban runoff are significant in relation to other nonpoint
sources (even in the absence of point source discharges) are indicated to
be highly susceptible to eutrophication and that urban runoff control may
be warranted in such situations.
2. Coliform bacteria discharges in urban runoff have a significant negative
impact on the recreational uses of lakes.
As was the case with rivers and streams, coliform bacteria in urban run-
off can cause violations of criteria for the recreational use of lakes.
When unusually high fecal coliform counts are observed, they may be par-
tially attributable to sanitary sewage contamination, in which case
significant health risks may be involved.
The Lake Quinsigamond NURP project in Massachusetts found that bacterial
pollution was widespread throughout the drainage basin. In all cases
where samples were taken, fecal coliforms were in excess of 10,000 counts
per 100 ml, with conditions worse in the Belmont street storm drains.
This project concluded that the very high fecal coliform counts in their
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stormwater are at least partially due to sewage contamination apparently
entering the stormwater system throughout the local catchment.
The sources of sewage contamination are leaking septic tanks, infiltra-
tion from sanitary sewers into storm sewers, and leakage at manholes. In
the northern basin, the high fecal coliform counts are attributed to
known sewage contamination sources on Poor Farm Brook. The data from the
project suggest that it would be unwise to permit body contact recreation
in the northern basin of the lake during or immediately following signif-
icant storm events. The project concluded that disinfection at selected
storm drains should be considered in the future, especially if the sewage
contamination cannot be eliminated.
The Mystic River NURP project in Massachusetts found various areas where
fecal coliform counts were extremely high in urban stormwater. Fecal
coliform levels of up to one million with an average of 178,000/100 ml
were recorded in Sweetwater Brook, a tributary to Mystic River, during
wet weather. These high fecal coliform levels were specifically attrib-
uted to surcharging in their sanitary sewers, which caused sanitary
sewage to overflow into their storm drains via the combined manholes
present in this cathcment. Fecal coliform levels above the class B fecal
coliform standard of 200 per 100 ml were found in approximately one-third
of the samples tested in the upper and lower forebays of the Upper Mystic
Lake and occasionally near the lake's outlet. In addition, Sandy Beach,
a public swimming area on Upper Mystic Lake, exceeded the State fecal
coliform criteria in July of 1982, and warnings that swimming may be haz-
ardous to public health were posted for several days. It is important to
note that sewage contamination of surface waters is a major problem in
the watershed. The project concluded that urban runoff contributes to
the bacteria load during wet weather but, comparatively, is much less
significant than the sanitary sources.
Estuaries and Embayments
1. Adverse effects of urban runoff in marine waters will be a highly speci-
fic local situation. Though estuaries and embayments were studied to a
very limited extent in NURP, they are not believed to be generally
threatened by urban runoff, though specific instances where use is im-
paired or denied can be of significant local and even regional impor-
tance. Coliform bacteria present in urban runoff is the primary
pollutant of concern, causing direct impacts on shellfish harvesting and
beach closures.
The significant impact of urban runoff on shellfish harvesting has been
well documented by the Long Island, New York NURP project. In this proj-
ect, stormwater runoff was identified as the major source of bacterial
loading to marine waters and, thus, the indirect cause of the denial of
certification by the New York State Department of Conservation for about
one-fourth of the shellfishing area. Much of this area is along the
south shore, where the annual commercial shellfish harvest is valued at
approximately $17.5 million.
The Myrtle Beach, South Carolina NURP project found that stormwater dis-
charges from the City of Myrtle Beach directly onto the beach showed high
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bacterial counts for short durations immediately after storm events. In
many instances these counts violated EPA water quality criteria for aqua-
tic life and contact recreation. The high bacteria counts, however, were
associated with standing pools formed at the end of collectors for brief
periods following the cessation of rainfall and before the runoff perco-
lated into the sand. Consequently, the threat to public health was not
considered great enough to warrant closure of the beach.
Groundwater Aquifers
1. Groundwater aquifers that receive deliberate recharge of urban runoff do
not appear to be imminently threatened by this practice at the two loca-
tions where it was investigated.
Two NURP projects (Long Island and Fresno) are situated over sole source
acquifers. They have been practicing recharge with urban runoff for two
decades or more at some sites, and extensively investigated the impact of
this practice on the quality of their groundwater. They both found that
soil processes are efficient in retaining urban runoff pollutants quite
close to the land surface, and concluded that no change in the use of
recharge basins is warranted.
Despite the fact that some of these basins have been in service for rela-
tively long periods of time and pollutant breakthrough of the upper soil
layers has not occurred, the ability of the soil to continue to retain
pollutants is unknown. Further attention to this issue is recommended.
CONTROL EFFECTIVENESS
General
A limited number of techniques for the control of urban runoff quality were
evaluated by the NURP program. The set is considerably smaller than prev-
iously published lists of potential management practices. Since the control
approaches that were investigated were selected at the local level, the
choices may be taken as an initial indication of local perceptions regarding
practicality and feasibility from the standpoint of implementation.
Conclusions
1. There is a strong preference for detention devices, street sweeping, and
recharge devices as reflected by the control measures selected at the
local level for detailed investigation. Interest was also shown in grass
swales and wetlands.
Six NURP projects monitored the performance of a total of 14 detention
devices. Five separate projects conducted in-depth studies of the
effectiveness of street sweeping on the control of urban runoff quality.
A total of 17 separate study catchments were involved in this effort.
Three NURP projects examined either the potential of recharge devices to
reduce discharges of urban runoff to surface waters or the potential of
the practice to contaminate groundwaters. A total of 12 separate sites
were covered by this effort.
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Grass swales were studied by two NURP projects. Two swales in existing
residential areas, and one experimental swale constructed to serve a com-
mercial parking lot were studied.
A number of NURP projects indicated interest in wetlands for improving
urban runoff quality at early stages of the program. Only one allocated
monitoring activity to this control measure, however.
Various other management practices were identified as having local inter-
est by individual NURP projects, but none of them was allocated the
necessary resources to be pursued to a point which allowed an evaluation
of their ability to control pollution from urban runoff. Management
practices in this category included urban housekeeping (e.g., litter
programs, catch basin cleaning, pet ordinances) and public information
programs.
2. Detention basins are capable of providing very effective removal of pol-
lutants in urban runoff. Both the design concept and the size of the
basin in relation to the urban area served have a'critical influence on
performance capability.
Wet basins (designs which maintain a permanent water pool) have the
greatest performance capabilities. Observed pollutant reductions varied
from excellent to very poor in the basins which were monitored. However,
when basins are adequately sized, particulate removals in excess of
90 percent (TSS, lead) can be obtained. Pollutants with significant sol-
uble fractions in urban runoff show lower reductions; on the order of
65 percent for total P and approximately 50 percent for BOD, COD, TKN,
Copper, and Zinc. Results indicate that biological processes which are
operative in the permanent pool produce significant reductions (50 per-
cent or more) in soluble nutrients, nitrate and soluble phosphorus.
These performance characteristics are indicated by both the NURP analysis
results and conclusions reached by individual projects.
Dry basins, (conventional stormwater management basins), which are de-
signed to attenuate peak runoff rates and hence only very briefly detain
portions of flow from the larger storms, are indicated by NURP data to be
essentially ineffective for reducing pollutant loads.
Dual-purpose basins (conventional dry basins with modified outlet struc-
tures which significantly extend detention time) are suggested by limited
NURP data to provide effective reductions in urban runoff loads. Per-
formance may approach that of wet ponds; however, the additional proc-
esses which reduce soluble nutrient forms do not appear to be operative
in these basins. This design concept is particularly promising because
it represents a cost effective approach to combining flood control and
runoff quality control and because of the potential for converting
existing conventional stormwater management ponds.
Approximate costs of wet pond designs are estimated to be in the order of
$500 to $1500 per acre of urban area served, for on-site applications
serving relatively small urban areas, and about $100 to $250 per acre
of urban area for off-site applications serving relatively large urban
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areas. The costs reflect present value amounts which include both capi-
tal and operating costs. The difference is due to an economy of scale
associated with large basin volumes. The range reflects differences in
size required to produce particulate removals in the order of 50 percent
or 90 percent. Annual costs per acre of urban area served are estimated
at $60 to $175, and $10 to $25 respectively.
3. Recharge Devices are capable of providing very effective control of urban
runoff pollutant discharges to surface waters. Although continued atten-
tion is warranted, present evidence does not indicate that significant
groundwater contamination will result from this practice.
Both individual project results and NURP screening analyses indicate that
adequately sized recharge devices are capable of providing high levels of
reduction in direct discharges of urban runoff to surface waters. The
level of performance will depend on both the size of the unit and the
soil permeability.
Application will be restricted to areas where conditions are favorable.
Soil type, depth to groundwater, land slopes, and proximity of water
supply wells will all influence the appropriateness of this control
technique.
Surface accumulations which result from the high efficiency of soils to
retain pollutants, suggest further attention in applications where dual
purpose recharge areas also serve as recreational fields or playground
areas.
4. Street sweeping is generally ineffective as a technique for improving the
quality of urban runoff.
Five NURP projects evaluated street sweeping as a management practice to
control pollutants in urban runoff. Four of these projects concluded
that street sweeping was not effective for this purpose. The fifth,
which had pronounced wet and dry seasons, believed that sweeping just
prior to the rainy season could produce some benefit in terms of reduced
pollution in urban runoff.
A large data base on the quality of urban runoff from street sweeping
test sites was obtained. At 10 study sites selected for detailed analy-
sis, a total of 381 storm events were monitored under control conditions,
and an additional 277 events during periods when street sweeping opera-
tions were in effect. Analysis of these data indicated that no signifi-
cant reductions in pollutant concentrations in urban runoff were produced
by street sweeping.
There may be special cases in which street cleaning applied at restricted
locations or times of year could provide improvements in urban runoff
quality. Some examples that have been suggested, though not demonstrated
by the NURP program, include periods following snow melt or leaf fall,
or urban neighborhoods where the general level of cleanliness could be
significantly improved.
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5. Grass swales can provide moderate improvements in urban runoff quality.
Design conditions are important. Additional study could significantly
enhance the performance capabilities of swales.
Concentration reductions of about 50 percent for heavy metals, and
25 percent for COD, nitrate, and ammonia were observed in one of the
swales studied. However the swale was ineffective in reducing concen-
trations of organic nitrogen, phosphorus, or bacterial species. Two
other swales studied failed to demonstrate any quality improvements in
the urban runoff passing through them.
Evaluations by the NURP projects involved concluded, however, that this
was an attractive control technique whose performance could be improved
substantially by application of appropriate design considerations. Addi-
tional study to develop such information was recommended.
Design considerations cited included slope, vegetation type and mainte-
nance, control of flow velocity and residence time, and enhancement of
infiltration. The latter factor could produce load reductions greater
than those inferred from concentration changes and effect reductions in
those pollutant species which are not attenuated by flow through the
swale.
6. Wetlands are considered to be a promising technique for control of urban
runoff quality. However, neither performance characteristics nor design
characteristics in relation to performance were developed by NURP.
Although a number of projects indicated interest, only one assigned NURP
monitoring activity to a wetland. This was a natural wetland, and flows
passing though it were uncontrolled. Results suggest its potential to
improve quality, but the investigation was not adequate to associate
necessary design factors to performance capability. Additional attention
to this control technique would be useful, and should include factors
such as the need for maintenance harvesting to prevent constituent
recycling.
ISSUES
A number of issues with respect to managing and controlling urban runoff
emerge from the conclusions summarized above. In some instances they repre-
sent the need for additional data/information or for further study. In
others they point to the need for follow-up activity by EPA, State, or local
officials to assemble and disseminate what is already known regarding water
quality problems caused by urban runoff and solutions.
Sediments
The nature and scope of the potential long-term threat posed by nutrient and
toxic pollutant accumulation in the sediments of urban lakes and streams
requires further study. A related issue is the safe and environmentally
sound disposal of sediments collected in detention basins used to control
urban runoff.
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Priority Pollutants
NURP clearly demonstrated that many priority pollutants can be found in urban
runoff and noted that a serious human health risk could exist when water sup-
ply intakes are in close proximity to urban stormwater discharges. However,
questions related to the sources, fate, and transport mechanisms of priority
pollutants borne by urban runoff and their frequencies of occurrence will
require further study.
Rainfall pH Effects
The relationship between pH and heavy metal values in urban runoff has not
been established and needs further study. Several NURP projects (mostly in
the northeastern states) attributed high heavy metals concentrations in urban
runoff to the effects of acid rain. Although it is quite plausible that acid
rain increases the level of pollutants in urban runoff and may transform them
to more toxic and more easily assimilated forms, further study is required to
support this speculation.
Industrial Runoff
No truly industrial sites (as opposed to industrial parks) were included in
any of the NURP projects. A very limited body of data suggests, however,
that runoff from industrial sites may have significantly higher contaminant
levels than runoff from other urban land use sites, and this issue should be
investigated further.
Central Business Districts
Data on the characteristics of urban runoff from central business districts
are quite limited as opposed to other land use categories investigated by
NURP. The data do suggest, however, that some sites may produce pollutant
concentrations in runoff that are significantly higher than those from other
sites in a given urban area. When combined with their typically high degrees
of imperviousness, the pollutant loads from central business districts can be
quite high indeed. The opportunities for control in central business dis-
tricts are quite limited, however.
Physical Effects
Several projects concluded that the physical impacts of urban runoff upon
receiving waters have received too little attention and, in some cases, are
more important determinants of beneficial use attainment than chemical pol-
lutants. This contention requires much more detailed documentation.
Synergy
NURP did not evaluate the synergistic effects that might result from pollut-
ant concentrations experienced in stormwater runoff, in association with pH
and temperature ranges that occur in the receiving waters. This type of in-
vestigation might reveal that control of a specific parameter, such as pH,
would adequately reduce an adverse synergistic effect caused by the presence
of other pollutants in combination and be the most cost effective solution.
Further investigations should include this issue.
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Opportunities for Control
Based upon the results of NURP's evaluation of the performance of urban run-
off controls, opportunities for significant control of urban runoff quality
are much greater for newly developing areas. Institutional considerations
and availability of space are the key factors. Guidance on this issue in a
form useful to States and urban planning authorities should be prepared and
issued.
Wet Weather Water Quality Standards
The NURP experience suggests that EPA should evaluate the possible need to
develop "wet weather" standards, criteria, or modifications to ambient crite-
ria to reflect differences in impact due to the intermittent, short duration
exposures characteristic of urban runoff and other nonpoint source
discharges.
Coliform Bacteria
The appropriateness of using coliform bacteria as indicator organisms for
human health risk where the source is exclusively urban runoff warrants fur-
ther investigation.
Wetlands
The use of wetlands as a control measure is of great interest in many areas,
but the necessary information on design performance relationships required
before cost effective applications can be considered has not been adequately
documented. The environmental impacts of such use upon wetlands is a
critical issue which, at present, has been addressed marginally, if at all.
Swales
The use of grass swales was suggested by two NURP projects to represent a
very promising control opportunity. However, their performance is very
dependent upon design features about which information is lacking. Further
work to address this deficiency and appropriate maintenance practices appears
warranted.
Illicit Connections
A number of the NURP projects identified what appeared to be illicit connec-
tions of sanitary discharges to stormwater sewer systems, resulting in high
bacterial counts and dangers to public health. The costs and complications
of locating and eliminating such connections may pose a substantial problem
in urban areas, but the opportunities for dramatic improvement in the quality
of urban stormwater discharges certainly exist where this can be accom-
plished. Although not emphasized in the NURP effort, other than to assure
that the selected monitoring sites were free from sanitary sewage contamina-
tion, this BMP is clearly a desirable one to pursue.
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Erosion Controls
NURP did not consider conventional erosion control measures because the
information base concerning them was considered to be adequate. They are
effective, and their use should be encouraged.
Combined Sewer Overflows
In order to address urban runoff from separate storm sewers, NURP avoided any
sites where combined sewers existed. However, in view of their relative
levels of contamination, priority should be given to control of combined
sewer overflows.
Implementation Guidance
The NURP studies have greatly increased our knowledge of the characteristics
of urban runoff, its effects upon designated uses, and of the performance
efficiencies of selected control measures. They have also confirmed earlier
impressions that some States and local communities have actually begun to
develop and implement stormwater management programs incorporating water
quality objectives. However, such management initiatives are, at present,
scattered and localized. The experience gained from such efforts is both
needed and sought after by many other States and localities. Documentation,
evaluation, refinement and transfer of management and financing mechanisms/
arrangements, of simple and reliable problem assessment methodologies, and of
implementation guidance which can be used by planners and officials at the
State and local level are urgently needed as is a forum for the sharing of
experiences by those already involved, both among themselves and with those
who are about to address nonpoint source issues.
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APPENDIX
THE NATIONWIDE URBAN RUNOFF PROGRAM
Program Design
NURP was not intended to be a research program, per se, and was not designed
as such. Rather, the program was intended to be a support function which
would provide information and methodologies for water quality planning
efforts. Therefore, wherever possible, the projects selected were ones where
the work undertaken would complete the urban runoff elements of formal water
quality management plans and the results were likely to be incorporated in
future plan updates and lead to implementation of management recommendations.
Conduct of the program provided direction and assistance to 28 separate and
distinct planning projects, whose locations are shown in Figure 1 and listed
in Table 1, but the results will be of value to many other planning efforts.
NURP also acted as a clearinghouse and, in that capacity, provided a common
communication link to and among the 28 projects.
The NURP effort began with a careful review of what was known about urban
runoff mechanisms, problems, and controls, and then built upon this base.
The twin objectives of the program were to provide credible information on
which Federal, State, and local decision makers could base future urban
runoff management decisions and to support both planning and implementation
efforts at the 28 project locations.
An early step in implementing the NURP program involved identifying a limited
number of locations where intensive data gathering and study could be done.
Candidate locations were assessed relative to three basic selection criteria:
- Meeting program objectives;
Developing implementation plans for those areas; and
Demonstrating transferability, so that solutions and knowledge
gained in the study area could be applied in other areas, with-
out need for intensive, duplicative data gathering efforts.
The program design used for NURP included providing a full range of technical
and management assistance to each project as the needs arose. Several forums
for the communication of experience and sharing of data were provided through
semi-annual meetings involving participants from all projects. The roles and
responsibilities of the various State, local, and regional agencies and par-
ticipating Federal agencies were clearly defined and communicated at the
outset. These were reviewed and revised where warranted as the projects
progressed.
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Figure 1. Locations of the 28 NURP Projects
TABLE 1. NURP PROJECT LOCATIONS
EPA
Region
I
11
III
IV
NURP
Code
MAI
MA2
NH1
MY1
NY2
NY3
DC1
MD1
FL1
NCI
SCI
TNI
Project Name/Location
Lake Quinsigamond
(Boston Area)
Upper Mystic (Boston Area)
Durham, New Hampshire
Long Island (Nassau and
Suffolk Counties)
Lake George
Irondequoit Bay (Rochester
Area)
WASHCOG (Washington, D.C.
Metropolitan Area)
Baltimore, Maryland
Tampa, Florida
Winston-Salem, North Carolina
Myrtle Beach, South Carolina
Knoxville, Tennessee
EPA
Region
V
VI
VII
VIII
IX
X
NURP
Code
IL1
IL2
Mil
MI2
MI3
WI1
AR1
TX1
KS1
C01
SD1
UT1
CA1
CA2
OR1
WAI
Project Name/Location
Champaign-Urbana, Illinois
Lake Ellyn (Chicago Area)
Lansing, Michigan
SEMCOG (Detroit Area)
Ann Arbor, Michigan
Milwaukee, Wisconsin
Little Rock, Arkansas
Austin, Texas
Kansas City
Denver, Colorado
Rapid Citv, South Dakota
Salt Lake" City, Utah
Coyote Creek
(San Francisco Area)
Fresno, California
Springfield-Eugene, Oregon
Bellevue (Seattle Area)
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The 28 NURP projects were managed by designated State, county, city, or re-
gional governmental associations. The U.S. Geological Survey (USGS) was
involved with EPA as a cooperator, through an inter-agency agreement, on 11
of the NURP projects. The Tennessee Valley Authority was also involved in
one project.
Project Selection
Projects were selected from among the 93 Areawide Agencies that had iden-
tified urban runoff as one of their significant problems. The intention was
to build upon what these agencies had already accomplished in their earlier
programs. Also, projects that would be a part of this program were screened
to be sure that they represented a broad range of certain characteristics
(e.g., hydrologic regimes, land uses, populations, drainage system types).
Actual selection of projects was a joint effort among the States, local
governments, and Regional EPA offices. The five major criteria used to
screen candidate projects were as follows:
1. Problem Identified. Had a problem relative to urban runoff
actually been identified? Could that problem be directly
related to separate storm sewer discharges? What pollutant or
pollutants were thought to be causing the problem? Using the
NURP problem identification categories, what was the "problem"
(i.e., denying a beneficial use, violating a State water
quality standard, or public concern)?
2. Type of Receiving Water. The effects of stormwater runoff on
receiving water quality were the NURP program's ultimate con-
cern. Because flowing streams, tidal rivers, estuaries,
oceans, impoundments, and lakes all have different hydrologic
and water quality responses, the types of receiving waters
associated with each candidate project had to be examined to
ensure that an appropriately representative mix was included in
the overall NURP program.
3. Hydrologic Characteristics. The pattern of rainfall in the
study area is perhaps the single most important factor in
studying urban runoff phenomena, because it provides the means
of conveyance of pollutants from their source to the receiving
water. For this reason, projects in locations having different
hydrologic regimes were chosen for the program.
4. Urban Characteristics. Characteristics such as population
density, age of community, and land use were considered as
possible indicators of the waste loads and ultimately the
rainfall-runoff water quality relationship. The type of sewer-
age system was another factor considered (e.g., whether it is
combined, separate, or mixed; how severe the infiltration and
inflow problems may be) . Such factors have different effects
on the quantity and quality of storm runoff, and were balanced
as well as possible in selecting projects.
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5. Beneficial Use of Receiving Water. Because this factor greatly
affects the type of control measure that would be appropriate,
attempts were made to include a wide range in selecting
projects.
Although these were the primary criteria used to identify potential projects,
other factors also had to be considered (e.g., the applicant agencies'
willingness to participate, the State's acceptance of the project, the expe-
rience of the proposed project teams). Because the NURP program used
planning grants (not research funds) a major consideration was the antici-
pated working relationships with local public agencies and the applicants'
ability to raise local matching funds.
Program Assistance
Technical expertise and resources available for urban runoff planning varied
among the various projects participating in NURP. Therefore, the program
strategy called for providing a broad spectrum of technical assistance to
each project as needed and for intercommunication of experiences and sharing
of data in a timely manner.
Assistance was also provided to the applicants in developing their final work
plans. This was done to ensure that there would be consistency among
methods, especially in the collection of data. If there were to be differ-
ences in data from city to city, they must be due to the characteristics of
each city and not a result of how the data were obtained.
Assistance with instrumentation was provided during the program in the form
of information on available equipment, installation, calibration, etc. Be-
cause one of the more important elements of a data collection program is the
"goodness" or quality of the data themselves, questionable data would be of
little use. Accordingly, a quality assurance and quality control element was
required in the plans for each project.
Periodic visits were made to each project site to ensure that the partici-
pants were provided opportunities to discuss any problems, technical or ad-
ministrative. The visiting team typically included an EPA Regional Office
representative, an EPA Headquarters representative, and one or two expe-
rienced consultants. All interested parties, including representatives from
State or local governments, were requested to attend those visits.
As the projects moved farther into their planned activities and the time for
data analysis approached, each project was required to describe how they were
going to analyze their data. No single method was recommended for each proj-
ect, because it was believed that a broad diversity of available methods
would be suitable, if used properly. Guidance on proper use was provided as
a part of technical assistance through project visits and special workshops
for this purpose.
Communication
It was intended that the entire group of NURP participants function as a
single team. Accordingly, a communication program was developed. National
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meetings were conducted semi-annually so that key personnel from the indi-
vidual projects would have an opportunity to discuss their experiences and
findings.
Reports were required of each project quarterly. EPA Headquarters also pro-
vided composite quarterly reports summarizing the status of each project and
discussing problems encountered and solutions found.
OUTPUTS TRANSFERABLE TO STATE AND LOCAL GOVERNMENTS
The program has yielded a great deal of information which will be useful for
a broad spectrum of planning activities for many years. Furthermore, it has
fostered valuable cooperative relationships among planning and regulatory
agencies. The most tangible products of the program are this report, the
reports of various grantees (available under separate cover), and several
technical reports which focus on specialized aspects of the program, its
techniques, and its findings. In addition, a considerable number of indi-
vidual articles drawing on information developed under the, NURP program have
already appeared in the technical literature and address specific technical
or planning aspects of urban runoff.
At the time of publication of this Final Report, the main technical effort of
the NURP program is complete; the field studies and the analysis of most of
the resultant data are complete enough that the findings reported herein can
be taken with confidence. However, there is still some work in progress to
make certain details of the program available for future use. The products
of this on-going work include:
A detailed database which has been compiled to make technical
information from the 28 projects available for review and use
(DECEMBER 1985);
- A technical report which focuses on the program's studies and
findings relative to detention and recharge devices (MAY 1984) ;
- A technical report on urban runoff effects on the water quality
of rivers and streams (MARCH 1984); and
A technical report on the effectiveness of street sweeping as a
potential "best management practice" for water pollution control
(MAY 1984).
This report supersedes the earlier NURP publication, "Preliminary Results of
the Nationwide Urban Runoff Program," March 1982. Information presented
there has been expanded, updated, and in some cases revised.
24
•U.S. ooTZRmair PRIKTIKO omcs t 198* 0-421-082/519
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