Central Coast Post-Construction Stormwater Requirements

Resolution R3-2013-0032 Adopted July 12, 2013, Approving Post-Construction Stormwater Management Requirements for Development Projects in the Central Coast

• Resolution No. R3-2013-0032
  • Resolution Attachment 1: Post Construction Requirements
  • Resolution Attachment 2: Technical Support Document for Post-Construction Requirements
    • Technical Support Document, Attachment A: Watershed Management Zone Maps (8.6 MB)
    • Watershed Management Zone Maps were not included in Attachment A for following urban areas and is therefore provided below.
      • Cayucos
      • Elkorn
      • Lake Nacimiento
      • Mission Canyon
      • Mission Hills
      • San Miguel
      • Shandon
      • Torro Canyon
    • Additional Watershed Management Zones
    • Technical Support Document, Attachment D: Case Study of Hydrologic Benefits of On-Site Retention in the Central Coast Region
    • Technical Support Document, Attachment E: Methods and Findings of the Joint Effort for Hydromodification Control in the Central Coast Region (2.8MB)
    • Technical Support Document, Attachment G: Stormwater Control Measure Sizing
    • Technical Support Document, Attachment H: Support for Selection of Criteria

85th and 95th Percentile Rainfall Depths

The Central Coast Post-Construction Requirements stipulate that municipalities must require Regulated Projects to use rainfall statistics provided by the Central Coast Water Board or to calculate site-specific rainfall depths determined from local rainfall data using USEPA’s methodology (see Post-Construction Requirements Provision B.4.c). 

Rainfall Statistics Provided by the Central Coast Water Board:

• WARNING: Read instructions before downloading maps.
• 85th Percentile Rainfall Depth Maps (Adobe Reader, pdf)
• 95th Percentile Rainfall Depth Maps (Adobe Reader, pdf)


• Shapefiles of 85th and 95th Percentile Rainfall Depth Maps (GIS Shape Files)


• Memo Explaining Process for Developing Rainfall Depth Maps
• Memo Documenting Confidence Interval Accuracy of Rainfall Depths

Directions for Using Local Rainfall Data to Develop Site-Specific Rainfall Depths:

• Directions for Using Local Rainfall Data to Develop Site-Specific Rainfall Depths

Watershed Management Zones and Spatial Data Coverages

• Watershed Management Zones
• Physical Landscape Zones
• Receiving Water Type
• Groundwater Basins
• Geology
• Urban Nodes
• Hydrologic Soil Groups

Shapefile Descriptions

Download these coverages by clicking on the County name below. 
NOTE: Download times may be lengthy, depending on connection speeds; GIS Software is required to open files once downloaded to your computer system.

• Santa Cruz County (13 MB)
• Santa Clara County (6.8 MB)
• San Benito County (15.7 MB)
• Monterey County (36 MB)
• San Luis Obispo County (57.9 MB)
• Santa Barbara County (32.8 MB)

Implementation of Post-Construction Stormwater Requirements

Annual Reporting

• Annual Reporting Form

Technical Support for LID Implementation:

• Decentralized Stormwater Management Guidance
• Self-Retaining Area Guidance
• Stormwater Control Plan Template (MS Word)
• Flow Chart and Narrative for Meeting Retention Requirements (Performance Requirement No. 3)
• Native Soil Assessment for Small Infiltration-Based Stormwater Control Measures
• Steps for Successful LID Design
• LID Frequently Asked Questions (FAQ)

To Support Integration of Post-Construction Requirements into Municipal Requirements:

• User Guide for Municipal Implementation (PDF)
• User Guide for Municipal Implementation (MS Word)
• User Guide for Municipal Implementation – Flow Charts (MS PowerPoint)

Municipal Regulatory Update Training:

Webinar training series for the Municipal Regulatory Update Program (MRUAP) to aid local governments with review, revision, and presentation of new and amended regulatory language for LID.

To view the PowerPoint presentations used in the webinar, please click the links below:

• MRUAP Session One
• MRUAP Session Two

To download PowerPoint and webinar video files, please visit AHBL's FTP site.

Login using the following account (note, both the Username and Password are case sensitive).

• Username: MRUAP
• Password: MRUAP!

Gap Analysis Templates for Identifying Where Changes to Municipal Code are Needed to Promote LID:

• Hydromodification Control and LID Gap Analysis Template - Tacoma
• Hydromodification Control and LID Gap Analysis Template - Tacoma Excel Table
• Hydromodification Control and LID Gap Analysis Template - Generic

Development of the Central Coast’s Post-Construction Stormwater Requirements:

• Review of Existing Data
• Literature Review
• Watershed Characterization Part 1: Precipitation and Landscape
• Watershed Characterization Part 2: Watershed Management Zones and Receiving Water Conditions
• Linkage Analysis: Landscape Characterization, Receiving Water Conditions, Watershed Processes, and Human Disturbance

Additional Internet Resources:

• Central Coast LID Initiative
• State Water Board LID Webpage
• CASQA’s Low Impact Development Portal
• USEPA’s LID Webpage
• Achieving Sustainable Site Design through LID Practices, by Anne Guilette