Opportunities for U.S. Geological Survey Urban-Stormwater Investigations--National Pollution Discharge Elimination System Municipal Permitting Regulations,

In Reply Refer To                                June 14, 1991
Mail-Stop 415


Subject:  PROGRAMS AND PLANS--Opportunities for U.S. Geological
                              Survey Urban-Stormwater
                              Investigations--National Pollution
                              Discharge Elimination System
                              Municipal Permitting Regulations,
                              November 16, 1990

The U.S. Environmental Protection Agency (EPA) recently published a 
two-part municipal permitting regulation (Federal Register, November 
16, 1990) which offers opportunities for U.S. Geological Survey 
(USGS) urban-stormwater investigations both locally and nationally.  
Attachment 1 is a map of cities (population > 100,000) subject to 
these regulations.  [Note:  Attachments 1-6 are being mailed under 
separate cover to offices that might actually become involved in 
these investigations.]


USGS districts may choose to develop urban hydrology cooperative 
projects with local governments to characterize the quality of 
water in storm sewers.  Cities with a population greater than 
100,000 (1990 census) are required to comply with the regulations 
by May 1993; those with populations greater than 250,000 must 
comply by November 1992.  Attachments 2 and 3 summarize 
requirements for Part I and Part II of a city's National Pollution 
Discharge Elimination System (NPDES) permit application. Item III 
in Part II, Characterization Data, lists and describes in more 
detail the following four work elements that could involve USGS 

1.  For each city, data collection is required for 3 or more 
storm events at 5 to 10 gaging stations, including discharge data 
and water samples to analyze for about 140 chemical constituents.  
Data are to be collected from small catchments (1/2 sq. mi. or less) 
with a homogeneous land use.  Based on work published in Water-
Supply Paper (WSP) 2363, "Techniques for estimation of storm-runoff 
loads, volumes, and selected constituent concentrations in urban 
watersheds in the United States," by Nancy Driver and Gary Tasker, 
the Water Resources Division (WRD) recommends collection of samples 
for at least six storm events per site to achieve sound statistical 
analyses.  A bibliography of representative USGS reports in urban 
stormwater hydrology is given in Attachment 4.  Many of these 
studies were completed as part of the Nationwide Urban Runoff 
Program (NURP) in cooperation with the EPA.

2.  Annual and storm load estimates are to be made for a set of 
12 parameters of the 140 to be measured for individual storms.  
The 12 are:  biochemical oxygen demand (BOD), chemical oxygen 
demand, total suspended solids, dissolved solids, total nitrogen, 
total ammonia plus organic nitrogen, total phosphorus, dissolved 
phosphorus, cadmium, copper, lead, and zinc.  Estimates of annual 
loads can be made for each of these except BOD (an equation for 
BOD is not available) using the regional equations, validated with 
locally collected data, published in (WSP) 2363.

An extension of the computational method has been developed by
Tim Cohn, Branch of Systems Analysis, Gary Tasker, National Research 
Program, and Anne Hoos, Tennessee District, for adjusting regional 
equations with local data.  The extension procedure is available on 
USGS PR1ME computers and can be obtained through Gary Tasker, NRP, 
Reston, Virginia.

3.  NPDES application also requires that load estimates (for 
the same 12 parameters as above) be made for the entire urban area 
of each city.  Constituent-load estimates can be efficiently made 
using the WSP 2363 procedures linked to a Geographic Information 
System.  Application of this approach is being tested in the 
Dallas-Fort Worth area, where the Texas District has an urban 
hydrology stormwater project involving a 30-gage NPDES network, in 
cooperation with the North Central Texas Council of Governments.  
Attachment 5 is the project proposal for the Dallas-Fort Worth 
urban-hydrology project.

4.  EPA regulations require continued "monitoring" at the 
gaging sites during the 5-year term (following NPDES permit 
approval) of the NPDES permit to evaluate performance of a 
required stormwater-management program.  This required element 
affords an opportunity to extend and improve equations and 
estimates made under Part II of the NPDES permit application.  
Additionally, deterministic modeling could be evaluated during the 
monitoring term.  Additional references that are available for WRD 
districts preparing proposals include:

Berg, E. L., 1982, Handbook for Sampling and Sample Preservation 
of Water and Wastewater, U.S. Environmental Protection 
Agency, 414 p.

Tai, D., Jennings, M. E., White, K. D., and Garcia, L. A., 1991, 
Evaluation of a Modified Automatic Sampler for the Collection 
of Water Samples Containing Trace Organic Compounds or 
Suspended Sediment, U.S. Geological Survey Open-File Report 
(in process), 75 p.

Witkowski, P. J., Smith, J. A., Fusillo, T. V., 1982, Manmade Organic 
Compounds in the Surface Waters of the United States--A Review of 
Current Understanding, U.S. Geological Survey Circular 1007, 92 p.

Witkowski, P. J., Smith, J. A., Fusillo, T. V., and Chiou, C. T.,1987, 
A Review of Surface-Water Sediment Fractions and Their 
Interactions With Persistent Manmade Organic Compounds, 
U.S.Geological Survey Circular 993, 39 p.

The four areas of potential Geological Survey involvement can be 
shaped into a sound investigative project.  In addition, there may 
be an opportunity for new research to improve upon the national 
and regional equations of WSP 2363 by including local data to 
develop new locally applicable models to estimate urban-stormwater 


Results from the previous work under the NURP provide an important 
foundation for involvement with states in the NPDES process.  The 
NURP resulted in both the Driver and Tasker equations and a USGS- 
assembled national stormwater-hydrology data base. Specific site 
selection and storm-sampling criteria were used to produce the 
data base from which the equations were derived.  Involvement of 
WRD districts in the NPDES urban-stormwater investigations can 
extend USGS national data bases in urban-stormwater hydrology.  To 
improve upon the NURP data base, several factors must be 

1.  Careful site selection is important.  Most basins monitored 
should fall within the characteristics of the NURP basins for 
each region, especially if a project will use the Driver and 
Tasker equations for load estimation.

2.  Consider selecting sites in locations intended for Best 
Management Practice (BMP) modification under the permit 
monitoring effort.  Monitoring BMP-effected basins is necessary 
for NPDES permit evaluation.

3.  Storm sampling should follow the same criteria as used to 
define storms for the NURP data base (see WSP 2363).  Thus, 
samples should be collected over the entire hydrograph, not 
just the first 3 hours.

4.  Collection of snowmelt samples alone may not be adequate in 
determining mean annual loads, especially in areas where frozen 
precipitation accounts for less than half the annual 
precipitation volume.


In development of project proposals, WRD districts should include 
identification of the analytical methods they plan to use.  
Methodologies should be approved or accepted by EPA prior to 
initiation of the study.  Approval can be negotiated with the EPA 
Regional Office.  A listing of USGS lab methods and capabilities 
is attached (Attachment 6) and can be used to describe available 
methods to cooperators and EPA.

Project proposals further should include a description of adequate 
quality-assurance procedures.  These procedures should include:  
protocols for sampler cleaning, sample collection, and processing 
of blanks, spikes, and splits.  Protocols will be developed by the 
National Water Quality Laboratory (NWQL); Mark Sandstrom will 

WRD districts should contact NWQL (Doug Maingold, Merle Shockey, 
or Rich Hawkinson) as soon as new projects emerge to develop a 
priority commitment with NWQL, especially if a project will 
require analytical results within a predetermined timeframe.  If 
NWQL capacity is exceeded, use of contract laboratories may be an 
option.  To assist in interlaboratory bias assessment when 
analyses are provided by multiple laboratories, it is recommended 
that quality-assurance procedures include at least 5 percent 
split-sample analyses by participating laboratories.

NPDES permit applications require characterization and load 
estimation for volatile organic compounds (VOC).  Presently, the 
Hydrologic Instrumentation Facility is evaluating adaptations to 
automatic samplers that will allow collection of VOCs.  Contact 
Doreen Tai for status of sampler modifications.


WRD plans to fully support WRD district efforts in NPDES urban- 
stormwater investigations, as was done with NURP urban-stormwater 
investigations during 1978-1983.  A coordination team composed of 
representatives from the Office of Surface Water, Office of Water 
Quality, NRP, and NWQL is overseeing the NPDES urban hydrology study 
efforts.  An initial workshop was held on February 13, 1991, in 
Nashville, Tennessee.

It is suggested that Districts contact city government officials 
as soon as possible (see Dallas-Fort Worth study work element/time 
lines) in public works and environmental offices if USGS 
involvement is desired.  For studies to begin in fiscal year 1992, 
cities with populations greater than 250,000 should be contacted 
as soon as possible. If interest is sufficient, a national 
workshop on NPDES urban hydrology investigations may be held in 
Dallas in early July 1991.  Districts desiring additional 
information regarding the EPA regulations or future workshops may 
contact Marshall Jennings, Urban Hydrology Studies Coordinator for 
the Office of Surface Water (FTS 873-3068) Austin, Texas, or 
Timothy Miller, Office of Water Quality (FTS 959-6868), Reston, 

David A. Rickert, Chief                 Charles W. Boning, Chief
Office of Water Quality                 Office of Surface Water