CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD
SAN FRANCISCO
BAY REGION
ORDER NO. 01-119
NPDES PERMIT NO. CAS029718
AMENDMENT REVISING PROVISION C.3. OF ORDER NO. 01-024 FOR:
SANTA CLARA VALLEY WATER
DISTRICT, COUNTY OF SANTA CLARA, CITY OF CAMPBELL, CITY OF CUPERTINO, CITY OF
LOS ALTOS, TOWN OF LOS ALTOS HILLS, TOWN OF LOS GATOS, CITY OF MILPITAS, CITY
OF MONTE SERENO, CITY OF MOUNTAIN VIEW, CITY OF PALO ALTO, CITY OF SAN JOSE,
CITY OF SANTA CLARA, CITY OF SARATOGA, AND CITY OF SUNNYVALE, which have joined
together to form the SANTA CLARA VALLEY URBAN RUNOFF POLLUTION PREVENTION
PROGRAM
The California Regional
Water Quality Control Board, San Francisco Bay Region, hereinafter referred to
as the Regional Board, finds that:
1.
The
Regional Board adopted Order No. 01-024 on February 21, 2001, reissuing waste
discharge requirements under the National Pollutant Discharge Elimination
System (NPDES) permit for the Santa Clara Valley Urban Runoff Pollution Prevention
Program (Program) for the discharge of stormwater to South San Francisco Bay
and its tributaries. The Program’s
NPDES permit is jointly issued to the thirteen Cities of Santa Clara County
named above, Santa Clara County and the Santa Clara Valley Water District, all
of which are Co-permittees. These
Co-permittees are referred to as the Dischargers.
2.
As
outlined in Finding 17 of Order No. 01-024, Provision C.3. of Order No. 01-024
is to be revised in response to the “Cities of Bellflower, et. al.” decision by
the State Water Resources Control Board (State Board Order No. 2000-11).
3.
Order
No. 01-024 recognizes the Santa Clara Valley Urban Runoff Management Plan (Management Plan) as the
Dischargers’ Comprehensive Control Program and requires implementation of the
Management Plan, which describes a framework for management of stormwater
discharges. The 1997 Management Plan
describes the Program's goals and objectives and contains Performance
Standards, which represent the baseline level of effort required of each of the
Dischargers. The Management Plan
contains Performance Standards for seven different stormwater management
activities.
4.
Urban
Development Increases Pollutant Load, Volume, and Velocity of Runoff: During
urban development two important changes occur.
First, where no urban development has previously occurred, natural
vegetated pervious ground cover is converted to impervious surfaces such as
paved highways, streets, rooftops, and parking lots. Natural vegetated soil can both absorb rainwater and remove
pollutants providing a very effective natural purification process. Because pavement and concrete can neither absorb
water nor remove pollutants, the natural purification characteristics of the
land are lost. Secondly, urban
development creates new pollution sources as human population density increases
and brings with it proportionately higher levels of car emissions, car
maintenance wastes, municipal sewage, pesticides, household hazardous wastes,
pet wastes, trash, etc., which can be washed into the municipal separate storm
sewer system (MS4). As a result of
these two changes, the runoff leaving a newly developed urban area may be
significantly greater in volume, velocity and/or pollutant load than
pre-development runoff from the same area.
5.
Certain
pollutants present in stormwater and/or urban runoff may be derived from
extraneous sources that dischargers have limited or no direct jurisdiction
over. Examples of such pollutants and
their respective sources are: PAHs which are products of internal combustion
engine operation and other sources; heavy metals, such as copper from brake pad
wear and zinc from tire wear; dioxins as products of combustion; mercury
resulting from atmospheric deposition; and natural-occurring minerals from
local geology. All of these pollutants,
and others, may be deposited on impervious surfaces and roof-tops as fine
air-borne particles, thus yielding stormwater runoff pollution that is
unrelated to the particular activity or use associated with a given new or
redevelopment project. However,
dischargers can implement treatment control measures, or require developers to
implement treatment control measures, to reduce entry of these pollutants into
stormwater and their discharge to receiving waters.
6.
Pollutants
present in stormwater can have damaging effects on both human health and
aquatic ecosystems. In addition, the
increased flows and volumes of stormwater discharged from new impervious
surfaces resulting from new development and redevelopment can significantly
impact beneficial uses of aquatic ecosystems due to physical modifications of
watercourses, such as bank erosion and widening of channels.
7. Water Quality Degradation Increases with Percent Imperviousness: The increased volume and velocity of runoff
from newly developed urban areas can greatly accelerate the erosion of
downstream watercourses. A number of
studies have demonstrated a direct correlation between the degree of
imperviousness of an area and the degradation of beneficial uses of downstream
watercourses. Significant declines in
the biological integrity and physical habitat of streams and other receiving
waters have been found to occur with as little as a 10% conversion from natural
to impervious surfaces. Typical
medium-density single-family home projects developed in previously unurbanized
locations, range between 25 to 60% impervious.
Even at very low densities, such as 1-2 housing units per acre, some
types of subdivisions built in previously unurbanized locations can result in
more than a 10% increase in imperviousness.[1] Studies on the impacts of imperviousness on
beneficial uses of waters include
“Urbanization of aquatic systems:
Degradation thresholds, stormwater detection, and the limits of
mitigation,” Derek B. Booth and C. Rhett Jackson, Journal of the American Water
Resources Association 33(5), Oct. 1997, pp. 1077-1089; “Urbanization and Stream
Quality Impairment,” Richard D. Klein, Water Resources Bulletin 15(4), Aug.
1979, pp. 948-963; “Stream channel enlargement due to urbanization,” Thomas R.
Hammer, Water Resources Research 8(6), Dec. 1972, pp. 1530- 1540; and,
summaries of work on the impacts of imperviousness, including “The Importance
of Imperviousness,” in Watershed Protection Techniques 1(3), Fall 1994, pp.
100-111, and “Impervious surface coverage:
The emergence of a key environmental indicator,” Chester L. Arnold et
al., Journal of the American Planning Association 62(2), Spring 1996, pp.
243-259.
8. This Order, revising Provision C.3., is intended to enhance the
Dischargers’ existing Performance Standard for new development and significant
redevelopment. This Order more clearly
requires a level of implementation of best management practices (BMPs), including
treatment measures in new development and significant redevelopment, that
reflects the regulatory standard of maximum extent practicable (MEP). This is done through addition of
requirements to more effectively incorporate source control measures, site
design principles, and structural stormwater treatment controls in new
development and redevelopment projects in order to reduce water quality impacts
of stormwater runoff for the life of these projects. The consistent application of such measures is intended to
greatly reduce the adverse impacts of new development and redevelopment on
water quality and beneficial uses by reducing stormwater pollutant impacts, and
impacts of increases in peak runoff rate.
9. Cost-effective
opportunities to protect water quality in new and redevelopment may exist
during the land use approval process.
When a Discharger incorporates policies and principles designed to
safeguard water resources into its General Plan and development project
approval processes, it has taken a far-reaching step towards the preservation
of local water resources for future generations.
10. The revise