Watershed-Based Permitting Case Study
CUerru (ZreeK Reservoir
Colorado
Municipal Separate Storm Sewer Systems, Phase II Stormwater Permit
Permitting Authority Contacts:
Colorado Department of Public Health and Environment (CDPIHE)
Water Quality Control Division
4300 Cherry Creek Drive South
Denver, CO 80246-1530
Nathan T, Moore
(303) 692-3555
nathan.moore@state.co.us
Dick Parachini
(303) 692-3516
dick.parachini@state.co.us
Permit Type: General permit for small municipal separate storm
sewer systems
Effective Date: March 10, 2008
Expiration Date: March 9, 2013
Overview and Highlights
The Colorado Department of Public Health and Environ-
ment (CDPHE) developed a watershed-based Phase II
Stormwater permit for Municipal Separate Storm Sewer
Systems (MS4s) with discharges to the Cherry Creek
Reservoir drainage basin in Colorado. The permit includes
requirements for the Phase II Six Minimum Measures
for all permitted discharges (Public Education, Public
Involvement/Participation, Illicit Discharge Detection and
Elimination, Construction Site Stormwater Runoff Con-
trol, Post-Construction Stormwater Management, and
Pollution Prevention/Good Housekeeping [5 CCR 1002-
61.18(1 l)(a)(ii)(A)-(F)]) as well as additional best man-
agement practice (BMP) requirements and implementa-
tion schedules under the Public Education, Construction,
and Post-Construction BMP measures.
The permit requirements are based on the Cherry Creek
Reservoir Control Regulation No. 72 (Control Regulation),
which aims at protecting the reservoir's beneficial uses.
The watershed-based requirements of the permit imple-
ment the Control Regulation, and, therefore, the permit
requirements are modified through Colorado's triennial
review process for the Control Regulation. This process
provides for collaboration among permittees, the permit-
ting authority, and watershed stakeholders to review and
modify requirements every 3 years if needed.
Successful implementation of the permit, which is in its
second cycle, has been attributed to effectively educating
permittees and stakeholders and early cooperation among
permittees, CDPHE, and the Cherry Creek Basin Water
Quality Authority (Basin Authority) to develop requirements
Other Stakeholders:
Cherry Creek Basin Water Quality Authority
www.cherrycreekbasin.org/cc_home.asp
Cherry Creek Stewardship Partners
www.cherry-creek.org/
Pollutants and Indicators Addressed in Permit:
Phosphorus, pollutants associated with storm sewer discharges, chlorophyll a
Permit Information:
Permit: www.cdphe.state.co.us/wc|/PermitsUnit/stormwater/
2008MS4080000permit.pdf
Rationale: www,cdphe.state.co.us/wq/PermitsUnit/stormwater/
2008MS4080000rat.pdf
Watershed Cherry Creek (Colorado]
Key Water Quality Concerns: Moroptytt ^
Stakeholder Involvement Techniques:
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Statewide Watershed Approach
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Watershed-Based Permitting Case Study Cherry Creek Reservoir Dr^i^je Colorado
that are consistent with the regulations and feasible for
permittees to accomplish. This process has also fostered col-
laboration among permittees both across the watershed and
within jurisdictions to streamline compliance activities.
Permitting Background
Watershed Description
Cherry Creek flows north through the 245,500-acre Cherry
Creek Reservoir drainage basin toward its confluence with
the South Platte River, the point that marks the original
settlement of Denver, Colorado. The 850-acre Cherry Creek
Reservoir was built at the north end of the watershed for
flood control, but its proximity to the Denver metropolitan
area makes it a popular destination for swimming, boating,
and other recreational activities. The Cherry Creek State
Recreation Area surrounding the reservoir receives more than
1 million visitors each year.
Water Quality and Regulatory History
Cherry Creek Reservoir is designated for warm water aquatic
life, primary recreation, water supply, and agriculture uses.
In the early 1980s, a study identified phosphorus as the
nutrient critical to algal productivity in the reservoir. To
prevent eutrophication and protect the reservoir's beneficial
uses, CDPHE adopted the Control Regulation in 1985. The
Control Regulation established a total phosphorus numeric
water quality standard for the reservoir and introduced a
total phosphorus total maximum annual load (TMAL) and
implementation plan for the reservoir.
In 1988 legislative declaration (Colorado Revised Statutes
25-8.5-101 et seq.) established the Basin Authority to
develop and implement plans for water quality controls for
the Cherry Creek Basin. The Basin Authority is a quasi-mu-
nicipal corporation and political subdivision of Colorado that
has primary responsibility for water quality in the Cherry
Creek Basin. The Basin Authority reviews and makes recom-
mendations for technical specifications for new projects in
the Cherry Creek Basin and also implements its own work
plan. The Control Regulation requires the Basin Authority to
spend at least 60 percent of its funding on constructing and
maintaining pollutant-reduction facilities.
In 2000 CDPHE replaced the total phosphorus standard for
Cherry Creek Reservoir with a new water quality standard
for chlorophyll a along with a total phosphorus goal, rather
than a standard. CDPHE decided to use a response variable
(chlorophyll a level) rather than a causative variable (total
phosphorus) as the water quality standard because it more
directly relates to the reservoir's beneficial uses. CDPHE
then requested cooperation from the Basin Authority in
considering amendments to the existing Control Regulation
to implement the new standard for the Cherry Creek Basin.
Revisions to the Control Regulation in 2001 recognized that
Cherry Creek Reservoir was not attaining the chlorophyll a
standard. According to
the Basin Authority's
2006 Annual Report, the
annual phosphorus loads
to the reservoir since the
early 1990s have been
lower than the TMAL,
but the chlorophyll a
standard was achieved in
only 3 of the previous 15
years. The phosphorus
goal was never achieved
during the same pe-
riod. The revised Control
Regulation introduced
a phased approach to
implementing the phos-
phorus TMAL to facilitate
the additional investigations necessary to recalculate the
TMAL to meet the new chlorophyll a standard.
Other revisions to the Control Regulation incorporated the six
minimum measures required under the newly implemented
Phase II stormwater regulations. Furthermore, consistent with
the phosphorus TMAL, the Control Regulation includes spe-
cific requirements for regulated stormwater discharges in the
Cherry Creek Basin to control the discharge of nutrients to
the Cherry Creek Reservoir. The Control Regulation contains
requirements based on Colorado's Phase II Municipal Guid-
ance (Phase II Guidance, available at www.cdphe.state.co.us/
wq/PermitsUnit/stormwater/ms4guide.pdf) and the Basin
Authority's 2000 Cherry Creek Reservoir Watershed Storm-
water Quality Requirements (Cherry Creek Basin Stormwater
Requirements, available at www.cherrycreekbasin.org/pdf/
SW7o20Req.pdf).
Permit Development
In 2002 CDPHE initiated a watershed-based permitting ap-
proach in conjunction with the Basin Authority to implement
the Phase II stormwater provisions of the Control Regulation
within the context of the phosphorus TMAL. The general per-
mit, originally issued in March 2003 and reissued in March
2008, reflects the requirements of both the Phase II Guidance
and the Cherry Creek Basin Stormwater Requirements. Permit
requirements that apply to all permitted discharges are based
on the Phase II. Additional permit requirements for discharges
to the Cherry Creek Reservoir drainage basin are based on the
Cherry Creek Basin Stormwater Requirements.
More than 300 stakeholders were involved in developing the
permit, but the public process for the permit addressed only
the Phase II stormwater provisions. The watershed-based
permit provisions are strictly for implementing the Control
Regulation; therefore, stakeholder involvement that helped
shape the terms of the watershed-based permit provisions
occurred primarily during CDHPE's triennial review process
Stormwater Phase II
Minimum Measures
1. Public Education
2. Public Involvement/
Participation
3. Illicit Discharge Detection
and Elimination
4. Construction Site Storm-
water Runoff Control
5. Post-Construction Storm-
water Management
6. Pollution Prevention/
Good Housekeeping
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Watershed-Based Permitting Case Study Cherry Creek Reservoir Dr^i^je Colorado
for the Control Regulation. During the review process, the
Basin Authority held development meetings with stakehold-
ers including municipalities, industrial dischargers, and
water users.
The general permit was originally issued in March 2003. A
revised permit became effective on March 10, 2008. The
new permit revised only provisions of the permit applicable
to all municipalities; watershed-based provisions are un-
changed from the previous permit. The next triennial review
for the Control Regulation is scheduled for 2008. Changes
to the watershed-based permit provisions, which implement
the Control Regulation, will be made through the triennial
review process if needed.
Permit Strategy
The Colorado Discharge Permit System (CDPS) General
Permit for Stormwater Discharges Associated with Cherry
Creek Reservoir drainage basin MS4s (Watershed-based
Permit) was adopted to implement the watershed-based
Control Regulation, which includes phosphorus wasteload
allocations (WLA) to achieve the chlorophyll a standard for
the Cherry Creek Reservoir. Nineteen MS4s are covered
under the Watershed-based Permit—these are all the Phase
II stormwater MS4s with discharges to the Cherry Creek
Reservoir drainage basin. The permit includes requirements
for public education, construction, and post-construction
BMPs for discharges to the Cherry Creek drainage basin that
go beyond the basic Phase II stormwater requirements. The
additional requirements focus on nutrient reduction BMPs to
address the phosphorus TMAL.
Stakeholder involvement is a critical part of the permitting
strategy for the Watershed-based Permit. CDPHE, the Basin
Authority, all MS4s discharging to the Cherry Creek Basin,
Cherry Creek State Park, and wastewater treatment plants
coordinate through a Working Group organized as a subcom-
mittee of the Basin Authority in 2000 to revise the Control
Regulation that drives the Watershed-based Permit require-
ments. The Phase II Guidance that provides the basis for
many of the permit requirements encourages coordination
among permittees.
Although the permit itself is not directly linked to other
watershed-based programs, the permittees regularly work
with non-regulatory organizations. In particular, a stake-
holder organization known as the Cherry Creek Stewardship
Partners (see Permit Highlights below) is very involved
with the permittees in the Cherry Creek Basin and provides
compliance assistance and guidance for construction and
post-construction BMPs.
Permit Highlights
The Watershed-based Permit is primarily a traditional MS4
stormwater permit but includes additional watershed-based
requirements for discharges to the Cherry Creek Basin to
(1) help meet the phosphorus TMAL for stormwater sources
addressed by the Control Regulation, (2) support attainment
of the chlorophyll a standard and, (3) support the attain-
ment of designated uses in Cherry Creek Reservoir. CDPHE
has not identified specific administrative or programmatic
goals for the permit. There is a phosphorus trading program
in the watershed; however, neither the permit nor the Con-
trol Regulation directly incorporate water quality trading for
the regulated stormwater dischargers.
Permittee Coordination
Permittees and CDPHE have identified coordination among
permittees and other stakeholders as a major component
of successful implementation of the permit. Permittees and
other watershed stakeholders coordinate across the Cherry
Creek watershed and within jurisdictional boundaries to im-
plement activities under the general permit. Watershed-wide
coordination occurs primarily through the Basin Authority,
Cherry Creek Stewardship Partners, and cooperative groups
of MS4 permittees. The Phase II Guidance encourages coor-
dination among permittees.
Cherry Creek Basin Water Quality Authority (Basin Authority)
The Basin Authority comprises watershed stakeholders in-
cluding two counties, seven municipalities, one member rep-
resenting seven special districts (wastewater authorities and
districts), and seven private citizens who represent various
environmental and economic concerns and are appointed by
the Governor. As stated above, the Basin Authority makes
recommendations on proposed projects in the Cherry Creek
Basin including new wastewater treatment plants, expan-
sions for existing facilities, BMPs to be implemented by the
Basin Authority, and new construction projects submitted by
the Basin Authority or permittees. Permittees take the rec-
ommendations under advisement but are not required to act
on the Basin Authority's recommendations unless directed
by CDPHE.
The Working Group is a subcommittee of the Basin Author-
ity's Technical Advisory Committee. The Working Group
shares resources such as ordinances for construction require-
ments and public outreach materials among its members.
The Working Group is also coordinating with CDPHE to
determine what revisions might be necessary to the Control
Regulation during the upcoming triennial review.
Cherry Creek Stewardship Partners
Cherry Creek Stewardship Partners is a voluntary stakeholder
organization that focuses on public education. The voluntary
organization is composed predominantly of the same land
use agencies that make up the Basin Authority. A large por-
tion of the group's annual budget is provided by the Basin
Authority, which is funded through taxes and is committed to
spend a portion of its funds on public education. Although it
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Watershed-Based Permitting Case Study Cherry Creek Reservoir Dr^i^je Colorado
is a separate organization, Cherry Creek Stewardship
Partners acts as the public education arm of the Basin
Authority. Three subcommittees—water quality, education,
and open space—coordinate public education activities
such as field trips for children, train-the-trainer events, BMP
workshops, and technical seminars. The Cherry Creek Stew-
ardship Partners also provides compliance assistance and
guidance for construction and post-construction BMPs.
Cooperative Groups
The MS4 permittees in the Cherry Creek Basin have formed
cooperative groups within which permittees work together
and share resources to implement their requirements under
the Watershed-based Permit. Cooperative groups of permit-
tees share educational materials and technical resources
for permit compliance. Two examples of such cooperative
groups are the Douglas County Stormwater Co-op and Arap-
ahoe SPLASH (Stormwater Permittees for Local Awareness
of Stream Health). Some permittees have also organized a
stormwater utility to fund stormwater compliance activities
and infrastructure.
4 Ten to fifteen permittees coordinate efforts to imple-
ment Phase II requirements through the Douglas
County Stormwater Co-Op. The Co-Op began meet-
ing before the permit effective date to assemble the
permit application and develop a very detailed and
comprehensive Stormwater Management Program,
which has been used as a model for several other
Phase II stormwater management programs across the
country. To fulfill their public education requirements
under the permit, the co-op members worked together
to develop brochures that would meet all the permit-
tees' needs. This approach saved money by allowing
permittees to share printing and mailing costs.
4 Arapahoe SPLASH is a similar group of MS4 permit-
tees in Arapahoe County. Permittees work together
through Arapahoe SPLASH to provide educational
outreach, opportunities for public participation, and
staff training to increase public awareness of the role
of individuals in protecting water quality. SPLASH
members coordinate efforts under a Memorandum
of Understanding Cooperation Agreement between
governmental and quasi-governmental entities within
Arapahoe County to meet their Phase II requirements.
SPLASH events and education in the Cherry Creek
watershed are coordinated with the assistance of the
Cherry Creek Stewardship Partners.
4 Southeast Metro Stormwater Authority (SEMSWA) is
an independent stormwater utility formed in 2006 to
provide a funding mechanism for providing stormwater
services, including complying with Phase II storm-
water regulations. SEMSWA was formed through an
intergovernmental agreement (IGA) among the city of
Centennial, Arapahoe County, the Arapahoe County
Water and Wastewater Authority, East Cherry Creek
Valley Water and Sanitation District, and Inverness
Water and Sanitation District. The IGA was based on
recommendations from a local advisory committee
made up of homeowners associations, businesses,
schools, churches, and environmental groups, which
researched local stormwater runoff issues and cost-
effective solutions.
Planning Activities
Planning activities under the Watershed-based Permit are
consistent with Phase II stormwater requirements. Permit-
tees must develop a CDPS Stormwater Management Pro-
gram that addresses the Phase II Six Minimum Measures
and includes measureable goals. Measurable goals for each
of the six minimum measures must include dates for un-
dertaking the required actions, interim milestones, and the
frequency of the action. A fully developed program includes
standard operating procedures, supporting documentation,
implementation guidance, rules, and other elements neces-
sary to implement the Phase II requirements.
Permit Components
As discussed above, the Watershed-based Permit includes
all the required elements of a traditional Phase II stormwater
permit and additional requirements specific to discharges to
the Cherry Creek Reservoir drainage basin.
Effluent Limits
The permit contains the technology-based effluent limits (six
minimum measures) required under the Phase II Stormwater
regulations. For discharges to the Cherry Creek Reservoir
drainage basin, the permit also contains water quality-based
effluent limitations in the form of additional requirements un-
der the Public Education, Construction, and Post-Construc-
tion minimum measures that focus on controlling phospho-
rus. The additional requirements in the permit are primarily
for BMPs that affect the amount of phosphorus entering
the Cherry Creek Reservoir. The additional requirements for
Public Education require a focus on significant sources of
nutrients. The additional requirements for Construction and
Post-Construction are based on recommended procedures
outlined in the Basin Authority's Cherry Creek Reservoir Wa-
tershed—Stormwater Quality Model Stormwater Ordinance
(revised April 19, 2001), which is based on the Cherry
Creek Basin Stormwater Requirements. The general permit
also includes detailed requirements for BMPs taken from
the Model Ordinance. The table (right) outlines the effluent
limitations that are based on the Phase II Stormwater six
minimum measures and the additional requirements that
apply to discharges to the Cherry Creek Reservoir drainage
basin for the Public Education, Construction, and Post-
Construction minimum measures.
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Watershed-Based Permitting Case Study Cherry Creek Reservoir Dr^i^je Colorado
Table 1. Effluent Limitations
Phase II Minimum Control Measures for all
Permitted Discharges
Additional Requirements for Discharges to Cherry
Creek Reservoir Drainage Basin
Public Education
Implement a public education program to promote behavior
change to reduce water quality effects from stormwater runoff
and illicit discharges
* Target specific pollutants that affect or could affect beneficial
uses
* Conduct outreach about effects of stormwater discharges and
steps the public can take to reduce pollutants in stormwater
runoff
* Inform businesses and the public of municipal prohibitions
against illegal discharges
Conduct outreach focused on the stormwater sources likely to
contribute nutrient loads. The permit identifies specific sources
that should be addressed: chemical deicing, retailers that store
fertilizers outdoors, concentrated agricultural activities such
as turf farms, landscape plant facilities, and animal feeding
operations
Public Involvement/Participation
* Comply with applicable state, tribal, and local public notice
requirements
* Provide for public review and comment on the CDPS
Stormwater Management Program
No additional requirements
Illicit Discharge Detection and Elimination
* Develop a storm sewer system map showing all outfalls and
receiving waters
* Through an ordinance or other regulatory mechanism,
prohibit non-stormwater discharges into the MS4 and include
enforcement procedures
* Develop a plan to detect and address non-stormwater
discharges into the MS4ee
* Train municipal employees to recognize and respond to illicit
discharges
No additional requirements
Construction Site Stormwater Runoff Control
Develop, implement, and enforce a program to reduce pollutants
in, or prevent, construction site stormwater runoff to the MS4.
The program must include the following:
* A regulatory mechanism requiring the implementation of
proper erosion and sediment controls for construction sites,
including sanctions to ensure compliance
* Requirements for implementing appropriate BMPs for erosion
and sediment control and good housekeeping
* Procedures for construction site plan review and compliance
assessment
* Procedures for compliance assurance, including enforcement
procedures and sanctions as well as training for municipalities
and construction contractors on regulatory requirement
For new development and redevelopment projects permittees
must develop, implement, and enforce a program to control phos-
phorus discharges. The program must include construction BMPs
specified in the Control Regulation to accomplish the following:
* Phase construction activities to minimize exposed soil.
Disturbed areas 40 acres or more must not be exposed for
more than 30 days without stabilization. The permittee may
authorize exemptions to this requirement under specific
circumstances and with certain conditions.
* Reduce stormwater runoff flow to non-erosive velocities when
practicable.
* Protect state waters on construction sites from erosion and
sedimentation resulting from land disturbance.
* Control sediment before it leaves the construction site. Con-
struction sites must include at least one sediment entrapment
BMP before the stormwater exits the site and prevent deposition
of sediment off-site from vehicle tracking onto paved surfaces.
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Watershed-Based Permitting Case Study Cherrif Creek "Reservoir Pr^i^^e Colorado
Phase II Minimum Control Measures for all
Permitted Discharges
Additional Requirements for Discharges to Cherry
Creek Reservoir Drainage Basin
4 Stabilize all exposed disturbed areas where construction
activities are not taking place for longer than 14 days.
4 Revegetate disturbed areas within 14 days after construction
activity has ceased.
4 Inspect construction BMPs after installation, after any runoff
event, and at least every 14 days.
Post-Construction Stormwater Management
Develop, implement, and enforce a program to address storm-
water runoff from new development and redevelopment projects,
including the following:
4 Strategies that include a combination of structural or nonstruc-
tural BMPs, or both
* A regulatory mechanism that requires addressing post-con-
struction runoff
* Procedures to determine if BMPs are installed according to
specifications
4 Procedures to ensure long-term operation and maintenance of
BMPs, including enforcement procedures
4 An enforcement program
4 Procedures and mechanisms to track the location and ad-
equacy of long-term BMPs
Stormwater programs for development and redevelopment
projects must include the following:
4 Requirements for permanent BMP plan submittal, including
inspection and maintenance provisions.
4 Required permanent BMPs. The permit refers to require-
ments in the control regulation that specify use of permanent
BMPs with a water quality capture volume (WQCV) of at least
the 80th percentile runoff event. The Control Regulation
includes a list of approved BMPs that must be used to meet
the WQCV, as well as provisions for WQCV alternatives.
4 Provisions for permanent BMP inspections. The specific
requirements are detailed in the Control Regulation.
4 Additional BMP requirements for facilities with both construc-
tion and industrial stormwater requirements and for commer-
cial facilities. The additional BMPs are specified in the Control
Regulation.
4 Additional BMP requirements for stream preservation areas.
Specific areas are identified in the Control Regulation along
with BMPs to treat the WQCV for all runoff from land distur-
bance within the stream preservation areas.
4 Required permanent BMP operation and maintenance provi-
sions. The specific requirements are detailed in the control
regulation.
Pollution Prevention/Good Housekeeping
4 Develop and implement an operation and maintenance
program to prevent or reduce pollutant runoff from municipal
operations into the storm sewer system
4 Inform public employees of the effects of illegal discharges
and improper waste disposal
4 Prevent or reduce stormwater pollution from municipal facili-
ties and activities
No additional requirements
The original Watershed-based Permit aliowed phased devel-
opment and implementation for all permittees' Stormwater
Management Programs as long as the programs were fully
developed and implemented at the end of the 5-year permit
term. A schedule and measureabie goals for program devel-
opment had to be established through negotiations between
CDPHE and the permittee. For discharges to the Cherry
Creek Reservoir drainage basin, however, the original permit
included specific interim deadlines for the additional Public
Education, Construction, and Post-Construction requirements
to ensure implementation before the end of the permit term
in March 2008.
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Watershed-Based Permitting Case Study Cherry Creek Reservoir Dr^i^je Colorado
Monitoring and Reporting Requirements
Consistent with the Phase II stormwater regulations, there
are no overall monitoring requirements and no monitoring re-
quirements specific to the watershed-based provisions in the
permit, but monitoring can be required on a case-by-case
basis or if a total maximum daily load (TMDL) and WLAs ap-
ply to the receiving water.
All permittees must submit an annual report by March 10 of
each year for the preceding year. The elements of the annual
report address only the stormwater Phase II annual reporting
requirements, which focus largely on status reporting relative
to the Stormwater Management Program; there are no ad-
ditional watershed-based reporting requirements.
Permit Effectiveness
Environmental Benefits
Ultimately, reduction or maintenance of chlorophyll a levels
in the Cherry Creek Reservoir will demonstrate success of
the permit. To date, CDPHE has not yet identified progress
in terms of phosphorus reductions or resulting chlorophyll a
reductions, which might indicate a need to review the TMAL
to determine whether the nutrient WLAs and load allocations
are appropriate.
Benefits to the Permittee and Other Stakeholders
The permit has been successful from an implementation and
administrative standpoint. From a permittee's perspective,
a key component of the success of this permit has been the
excellent working relationship that exists between CDPHE
and the permittees. This relationship was established
early in the process of revising the Control Regulation and
developing the Phase II Guidance and has been maintained
through permit implementation and revision. At least one
permittee has found that cooperative, educated, and expe-
rienced regulators who are rigorous with respect to meeting
the requirements but who are also fair, flexible, and willing
to work with permittees are critical to the success of the
Watershed-based Permit.
Stakeholder education is also a key component to success.
CDPHE was astute in setting up the permittees' Working
Group and educating the regulated entities on the intent of
the regulations. This approach allowed the stakeholders to
work with CDPHE as it developed regulations and guidance
that meet the Phase II requirements and are feasible to
implement. For example, the Post-Construction BMPs control
measure in the Phase II regulations was an implementa-
tion challenge because many municipalities viewed it as an
unfunded mandate to take on long-term responsibility for
BMP maintenance where property managers, homeowners
associations, and similar entities are unable or unwilling to
fulfill their responsibilities. Early education and coordination
with CDPHE allowed some MS4s to form stormwater utilities
to provide a dedicated funding source for their post-construc-
tion BMP requirements.
Lessons Learned
Achieving consensus on the appropriate construction and
post-construction BMPs for discharges to the Cherry Creek
Reservoir drainage basin was one of the major challenges in
developing the watershed-based requirements in the Control
Regulation. Construction and post-construction BMPs in the
Control Regulation and permit are based on the Cherry Creek
Basin Stormwater Requirements and are selected through
a cooperative process between CDPHE and the watershed
stakeholders. At the same time, allowing the permittees
to play a significant role in developing the basis for permit
requirements has facilitated successful implementation of
the permit.
The interrelationship among the Cherry Creek Basin Storm-
water Requirements, the Phase II Guidance, the Control
Regulation, and the Watershed-based Permit has complicat-
ed the process of modifying the requirements when neces-
sary. CDPHE's Monitoring Program assesses the condition
of the reservoir to determine any needs for changes in the
Control Regulation. Any need for additional or reduced basin-
specific requirements that is based on water quality moni-
toring is addressed through the Control Regulation triennial
review process. Changes in the Control Regulation result
in changes to the permit. When changes to the BMPs are
needed, it is a challenge to make modifications to the guid-
ance documents that will translate to enforceable provisions
in the Control Regulation and permit. Some permittees have
also found the permit requirements to be too prescriptive.
The approach used in the Cherry Creek watershed could be
a useful model for other watersheds where the watershed-
based requirements are driven through a TMDL or regula-
tory process similar to the one in the Cherry Creek Basin.
Despite some of the additional complications of linking the
Cherry Creek Basin Stormwater Requirements, the Phase II
Guidance, the Control Regulation, and the Watershed-based
Permit, revising the watershed-based requirements through
a stakeholder process, driven by the TMAL and coordinated
with the Control Regulation triennial review generally has
worked well for Cherry Creek stakeholders.
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Watershed-Based Permitting Case Study Cherry Creek Reservoir Dr^i^je Colorado
Resources
Arapahoe County Stormwater Permittees for Local Awareness of Stream Health (SPLASH). No date. Araphahoe County
SPLASH, .
Brown and Caldwell. 2007. Cherry Creek Basin Water Quality Authority 2006 Annual Report on Activities.
.
Cherry Creek Basin Water Quality Authority. No date. Cherry Creek Basin Water Quality Authority.
.
Cherry Creek Basin Water Quality Authority. 2000. Cherry Creek Reservoir Watershed Stormwater Quality Requirements.
Cherry Creek Stewardship Partners. 2004. Cherry Creek Basin Water Stewardship and Education Initiative.
.
Cherry Creek Stewardship Partners. No date. Cherry Creek Stewardship Partners, .
CDPHE. 2002. Colorado Discharge Permit General Permit No. COR-080000.
.
CDPHE. No date. Stormwater Permitting. .
CDPHE, Water Quality Control Division. 2006. Colorado's Phase II Municipal Guidance. October 2001 (Resource list
updated June 2006).
CDPHE, Water Quality Control Division. 2003. Stormwater Annual Report—MS4s, Form arl2/03ms4.
CDPHE, Water Quality Control Commission. 2006. Regulation No. 38 (5 CCR 1002-38). Classifications and Numeric
Standards, South Platte River Basin, Laramie River Basin, Republican River Basin, Smoky Hill River Basin, as amended on
August 13, 2007.
CDPHE, Water Quality Control Commission. 2006. Regulation No. 61 (5 CCR 1002-61). Colorado Discharge Permit
System Regulations, as amended on February 13, 2006.
CDPHE, Water Quality Control Commission. 2004. Regulation No. 72. Cherry Creek Reservoir Control Regulation, as
amended on November 8, 2004.
SEMSWA (Southeast Metro Stormwater Authority). 2007. Welcome to the Southeast Metro Stormwater Authority.
.
Note: All Web references current as of March 14, 2008.
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