California State Stormwater Permit Requirements

California stormwater permit requirements
Michael Josselyn, PhD PWS
WRA, Inc.
November 2009

Purpose of presentation
How is stormwater regulated in California?

What require-ments have been set by state government?

What require-ments have been set by state government?
How are these regulations implemented?

Water quality regulations

Federal: Clean Water Act
Enacted in 1972 to protect nation’s water quality
Act prohibits the discharge of pollutants from a point source into “waters of the United States”
Unless a permit is obtained by the discharger
Environmental Protection Agency is given power to issue and enforce regulations
Permit program has been delegated to the State of California—NPDES permits
States also given power to approve wetland fill

stormwater regulations

Legal actions modify CWA
Congress issues Clean Water Act 1972
EPA decides not to regulate stormwater due to problems inherent in regulating many outfalls
Environmental organizations win law suits to have stormwater regulated under NPDES
Congress amends Clean Water Act 1987
Industrial stormwater discharges regulated
EPA considers construction activities to be industrial actions
1990 EPA mandated that construction activities be regulated under NPDES permits

State of California
State Water Resources Control Board is responsible for overall water management in the state
Defines stormwater as a
“pollutant” and as a
“point source”
Subject to permitting under NPDES
regulations
One source of stormwater
is from construction sites
September 2009: New regulations
for construction activities

Regional Authority
State divided into regions based on watershed boundaries
Each region responsible for separate “basin plans”
Regulate water quality to ensure beneficial uses of the streams and lakes in its region

California construction General Stormwater Permit
Established by State Water Resources Control Board
September 2, 2009

Why focus on construction sites?
20 to 1000 times more sediment from construction sites
Turbidity increases
Nutrient input higher
Sediment buildup in storm drainage devices

General permit: construction sites
Covers earth moving activities > 4000 sq m
Regulates the amount of sediment that can be discharged from construction sites
Sets standards for the discharge of certain pollutants
Turbidity and pH
Establishes a “design storm criteria”
Sets forth requirements related to risk level
Requires submission of Storm Water Quality Pollution Prevention Plan (SWPPP)

Establishes Risk Levels
Increasing level of protection
Sediment Risk = Type of activity and location of activity
Receiving Water Risk = “Sediment sensitivity” of water body

Sediment risk
Based on soil erosion factor
Calculated using Revised Universal Soil Loss Equation (RUSLE)
Considers
Rainfall
Soil Erodibility
Length-slope factor
Cover factor
Sediment controls

Revised universal soil loss equation
A = R * K * LS * C * P
A = the rate of sheet and rill erosion

A = R * K * LS * C * P
R = rainfall-runoff erosivityfactor

A = R * K * LS * C * P
R = rainfall-runoff erosivity factor
K = soil erodibility factor
LS = length-slope factor
K/ LS Factor map for California

A = R * K * LS * C * P
C = Cover Factor
P = Protection Measures employed

A = R * K * LS
C = Cover Factor = 1 for risk assessment
P = Protection Measures employed = 1

Sediment loss risk factors
Determine Value of A and relate risk below

Receiving water risk
Most sensitivity to sedimentation
Fish spawning areas
Fish migration areas
Any impaired water body for sediment

High RiSK = More controls
Use Standard Construction BMPs
Silt fences, hay bales, temporary detention
Additional Factors to be added
Ensure soil loss during each phase does not exceed preconstruction soil loss
More frequent inspections
Develop Rain Event Action Plans to prepare site within 48 hours in advance of rain events
Must meet numeric standards for Turbidity and pH
Establishes both action and limitation values

NUMERIC LIMITS
Turbidity
Action level = 250 NTU
Limit level = 500 NTU
Exceed Action Levels
Improve BMPs and implement corrective actions
Exceed Limit Levels
Additional monitoring and possible fines
pH
Action level = 6.5-8.5
Limit level = 6.0 – 9.0

Turbidity measurement

Minimize hydromodification
Runoff Project Water Flow
Pre Project Flows = Post Project Flows
Up to the 85th percentile storm event
Must consider both construction and post project features
Use of detention basins
Use of LID features
Maintaining natural vegetation and stream configurations within projects

Must submit stormwater plan:SWPPP
Must be prepared by a qualified individual
Evaluates Risk Factors
Describes all the best management practices
Describes compliance
plan
Provides for monitor-
ing and reporting

Watershed regulations
Wetland and Stream Protection

Water quality regulations

Wetland and stream fill protections
401 Water Quality Certification

Must approve loss of wetlands and streams in watersheds regulated by federal government
Must try to avoid and minimize impacts
Fill must be accompanied by wetland and stream replacement
Usually 2 to 3 times as much land as filled

Porter Cologne Act

Porter Cologne Act
Regulates fill placement in wetlands and streams
Cannot result in decreased beneficial uses
Fish habitat
Human use and health
Water quality

Watershed level regulation
No net loss of wetland and stream habitat
Requires that any loss be “mitigated”
Replacement areas must be in same watershed

Mitigation policies
Must create new wetlands and streams in greater quantity than lost—”Mitigation Ratio”
Wetlands and stream creation must maintain or reduce hydromodification
Wetland must be created similar to that which is lost
Performance standards must be met over 5 year monitoring program

Wetland mitigation areas
Freshwater marsh
Riparian and Meadow Habitat

Also applies to tidal areas
Batiquitos Lagoon
Channel Construction

Wetland creation technology
Has expanded significantly over past 20 years
Many wetland types
Freshwater marsh
Riparian habitat
Vernal pools
Streams
New policies in effect to improve science and performance

Mitigation banks
Established by private companies
Determine areas where development is occurring
Create wetland and stream habitat
May include habitat for unique plants and animals
Sell credits on the open market to private parties and governmental agencies
Must maintain these areas in perpetuity

Summary of state regulations
Strictly regulates construction activities
Sets methods to evaluate risk levels associated with various activities
Establishes numeric standards for some attributes
Seeks to control hydromodification
Incorporate features in project design to control flow
Regulates stream and wetland fill
Requires habitat replacement through mitigation
Sets standards for reporting and monitoring

California State Stormwater Permit Requirements

by Michael Josselyn

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