The Run-Off Report: What’s Changed: 2009 vs. 2022 CGP — Impacts for Projects in Region 1

The Run-Off Report: What’s Changed: 2009 vs. 2022 CGP — Impacts for Projects in Region 1

The California State Water Resources Control Board’s 2022 Construction General Permit (CGP), effective September 1, 2023, marks a pivotal shift in how stormwater is managed on construction sites. For permit holders in Region 1 (North Coast Regional Water Quality Control Board) — an area defined by its sensitive receiving waters, forested landscapes, and rugged coastal hydrology — these changes are more than administrative updates; they represent a redefined regulatory approach to water quality protection.

This article highlights the most significant changes between the 2009 CGP (Order 2009-0009-DWQ) and the 2022 CGP (Order 2022-0057-DWQ), and what they mean for your projects in Region 1.

1. TMDL Requirements Now Built Into the Permit

What's New: Attachment H of the 2022 CGP formally incorporates Total Maximum Daily Load (TMDL) implementation requirements, previously enforced through post-enrollment notices.

Region 1 Impact: Many watersheds in Region 1, such as the Russian River, are impaired for sediment, temperature, and pathogens. Now, projects in TMDL-listed watersheds must implement BMPs targeting specific pollutants (e.g., enhanced erosion control, winterization deadlines, turbidity monitoring). This raises the bar for compliance — especially for grading-heavy or forest-adjacent developments.

Takeaway: Projects must review TMDL maps and enforce watershed-specific BMPs from day one. Failure to implement the correct controls could lead to enforcement actions.

2. Numeric Action Levels (NALs) and Numeric Effluent Limitations (NELs) Expanded

What's New: The 2022 CGP introduces NALs and enforceable NELs for pH and turbidity, now applicable to more sites and tied to broader treatment requirements.

Region 1 Impact: Sites disturbing more than 1 acre and particularly those in Risk Level 2 or 3 must actively monitor discharges during qualifying storm events. Given the region’s steep slopes and high rainfall, construction sites are more likely to exceed thresholds — increasing the likelihood of mandated corrective actions.

Takeaway: Prepare for more monitoring, more reporting, and more liability. Consider including ATS (Active Treatment Systems) or sediment basins in your WPCPs/SWPPPs for high-risk sites.

3. Risk Determination: Revised Methodology

What's New: The 2022 permit updates the risk determination worksheet (Attachment D.1) and places a heavier emphasis on receiving water conditions, not just erosion potential and rainfall.

Region 1 Impact: Because many receiving waters in Region 1 are environmentally sensitive or impaired, more projects are expected to fall into Risk Level 2 or 3. This elevates compliance requirements, including:

• Mandatory Rain Event Action Plans (REAPs),

• Frequent inspections (every 24 hours during rain),

• Enhanced BMP implementation.

Takeaway: Assume higher risk designations in your planning stages and allocate more resources for monitoring and BMP installation upfront.

4. Passive and Active Treatment Provisions Clarified

What's New: Attachment G outlines specific design and operational requirements for passive treatment chemicals (e.g., flocculants, coagulants) and mandates certification for Active Treatment Systems (ATS).

Region 1 Impact: Given high turbidity potential in native soils, many Region 1 projects may benefit from flocculants or ATS — but must now follow stringent design, use, and training requirements.

Takeaway: Unpermitted chemical use is no longer tolerated. Ensure your SWPPP includes proper treatment designs and certified operators if needed.

5. Revised Training and Certification Requirements

What's New: The 2022 CGP now emphasizes the qualifications of site staff. The QSD/QSP roles remain, but there's increased scrutiny of field implementation.

Region 1 Impact: Inspectors and site managers must be up-to-date on training and capable of adapting BMPs in real-time during the region's intense and variable storm seasons.

Takeaway: Train your field personnel thoroughly. Documentation and implementation will be under tighter review from Regional Board inspectors.

6. Updated BMP Requirements and SWPPP Template Compatibility

What's New: The permit aligns more closely with the 2023 CASQA BMP Handbook, including enhanced definitions for BMP implementation, documentation, and inspection.

Region 1 Impact: This increases expectations for BMP maintenance — especially for erosion control blankets (ECBs), fiber rolls, inlet protection, and stabilized construction entrances. Failure to maintain or install per spec could now be a permit violation, not just a best practice failure.

Takeaway: Use the latest CASQA BMP Fact Sheets, integrate inspection logs, and ensure BMPs are implemented per detail.

Final Word: Adapt Early, Avoid Penalties

The 2022 CGP is more detailed, more enforceable, and more site-specific than its 2009 predecessor. For construction professionals in Region 1, adapting to these changes is not optional — it’s essential.

Start early, build smarter BMPs, train your crews, and integrate TMDL compliance into every phase. Doing so will not only help you stay in compliance — it will help protect some of California’s most critical and sensitive waterways.