Alternative Compliance Program

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City of Chula Vista’s Alternative Compliance In-Lieu Fee Program (Program) proposes the use of stream rehabilitation Natural Systems Management Practices (NSMP) as the mechanism for alternative compliance. The overall goal of this Program is to provide alternative mechanisms to meet stormwater compliance criteria while providing a greater water quality benefit and improved habitat within the City of Chula Vista’s (City) watersheds.

_{Example of Stream Rehabilitation with increased access to floodplain.}

WHAT is ACP (Alternative Compliance Program)?

The ACP is a mechanism for developing offsite water quality compliance through implementation of stream rehabilitation projects for Priority Development Projects.

Stream rehabilitation is a Natural Systems Management Practice (NSMP) that uses remedial measures or activities for the purpose of improving or restoring the beneficial uses of streams, channels, or river systems. Rehabilitation techniques may include but are not limited to the following: riparian zone restoration, constructed wetlands, channel modifications that improve habitat and stability, and daylighting of drainage systems.

The Program was developed using SB2 grant funding to provide an alternative pathway for compliance with water quality requirements in the San Diego Regional Municipal Separate Storm Sewer System (MS4) Permit (Order R9-2013-0001, as amended) (Regional MS4 Permit) and improve the overall habitat and watershed health within the City of Chula Vista. The Program was accepted by the San Diego RWQCB in August 2023.

The City has developed a Water Quality Equivalency (WQE) equation to determine the pollutant control credits provided by stream rehabilitation NSMPs based on three processes: (1) runoff retention, (2) sediment stabilization, and (3) vegetation biofiltration. The overall uplift in ecological benefits for a restored system is represented by a multiplier in the equation that increases credit volume.

In addition to developing a WQE for stream rehabilitation NSMPs, the City has developed an In-Lieu Fee (ILF) Program to generate water quality credits available for PDPs to purchase.

WHO can use ACP?

The Program was developed to provide Priority Development Projects (PDPs) within the City of Chula Vista’s borders with an off-site MS4 compliance option. PDPs are defined in detail in Section E.3.b(1) of the MS4 permit but include:

New development projects creating a minimum of 2,500-10,000 square feet of impervious surfaces, depending on location and type.
Redevelopment projects creating or replacing a minimum of 2,500-5,000 square feet of impervious surfaces, depending on location and type.

PDP participation in the ILF Program is allowed so long as there are credits available and the offsite alternative will have a greater overall water quality benefit than fully complying with the performance requirements of Provisions E.3.c.(1) and E.3.c.(2)(a) onsite. In addition, the PDP must use onsite flow-thru treatment control BMPs that are sized and implemented in accordance with Permit requirements.

Flow-thru treatment control BMPs are structural measures that provide flow-thru treatment as part of the pollutant control strategy. Examples include vegetated swales, media filters, sand filters, dry extended detention basins, and Washington State TAPE-certified¹ proprietary flow-thru treatment control.

^₁_{Washington Stormwater Center. 2023. Tape. Available: TAPE – Washington Stormwater Center (wastormwatercenter.org)}

HOW can I use the ACP?

A PDP applicant may choose to purchase credits developed under the City’s ILF program or propose an alternative compliance project to meet the PDP’s water quality credit needs. A PDP interested in utilizing the ACP Program should consult with the City early in the PDP development process.

Use of the ACP through the purchase of ILF water quality credits will be streamlined and similar to existing processes. Projects proposing development within the City’s jurisdiction will fill out the existing Storm Water Requirements Applicability Checklist for All Permit Applications (Intake Form). When prompted, the applicant will indicate their desire to utilize the City’s ILF Program to satisfy their MS4 requirements.

NSMP Pollutant Control Concept

Credits =Land use (∆Volume + Restored Volume*Condition (N₂) – Original Volume*Condition (N₁))

N =Effective Volume Retention + Sediment +Vegetation* Ecological Condition

A PDP applicant can also develop their own ACP stream rehabilitation project. Standard restoration design and methods should be used to develop a restoration project that will improve retention, sediment, and the ecological condition of the site. The NSMP Pollutant Control Concept shows the main factors that contribute to the credit development; Appendix B of the Program Guidance Document provides details on how to determine credits that a project will generate. The quantity of credits that an ACP project can produce is dependent on the land use factor, and influenced by the amount of water treated, reduction of sediment discharged from the site, and improvement in ecological conditions.

WHERE can I use ACP?

Location of an alternative compliance project will determine what area a PDP can be located to use credits. All ACP projects proposed under this program must be within the boundaries of the City of Chula Vista and may only provide credits for PDPs within the City of Chula Vista. The WQE Guidance and City of Chula Vista BMP Design Manual provides guidance on location requirements for an ACP project and where PDPs utilizing credits from the project may be located for both pollutant removal and hydromodification credits. This Program will use the same guidance and requirements for locating NSMP ACP projects approved under the program.

Figure 4-3 provides an overview of the City of Chula Vista’s jurisdictional boundaries, the Hydrologic Areas within the City’s limits, and the San Diego Bay WMA. The entire City is within the San Diego Bay WMA. This program further restricts the use of pollutant removal credits from an ACP project to PDPs within the same Hydrologic Area.

WHY should I use ACP?

The ILF Program provides regional benefits not realized through standard on-site compliance. These benefits include:

Generally more cost-effective solution for water quality compliance than full onsite treatment
Greater water quality benefit is achieved compared to onsite BMP implementation.
Facilitating implementation of watershed-scale natural system solutions that improve watershed functions and hydromodification impacts not met through project level onsite compliance.
Allowing developers to maximize the developable space within a PDP and support the City's housing and community development goals.
Improving local resiliency to climate change through stream rehabilitation.

Improves habitat and watershed health within Chula Vista

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City of Chula Vista

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