Stormwater Requirements for New Construction
Development Services Division ensures site plans incorporate the appropriate post-construction stormwater runoff controls. Staff can assist applicants with determining which State requirements apply to their project and provide reference resources for achieving compliance. Applicants are advised to consider post-construction runoff requirements during the site design process.
What is the process?
Determine Applicable Stormwater Management Requirements
There are two Post-Construction Stormwater standards currently in effect in San Luis Obispo County. The post-construction stormwater requirements summary chart summarizes the requirements and their applicability. Staff can help determine which requirements apply to the project.
Within the Phase II Municipal Permit Area (the County’s Stormwater Management Area) the County applies the Central Coast Post-Construction Requirements. Projects located outside the Stormwater Management Area (in unincorporated areas of the county) that disturb more than 1.0 acre must meet the Post-Construction Standards in the California Construction General Permit.
The County’s Land Use View mapping application can help you determine whether your project is located within the stormwater management area.
Incorporate Stormwater Management into Plans/Design
Permit applicants must submit either:
Projects within the County’s Municipal Stormwater Management Area (MS4 Coverage Area) must adhere to the Central Coast Post Construction Requirements.
Projects that do not receive a waiver must incorporate site design and runoff reduction measures during the projects planning stage. Projects subject to Performance Requirement 2 or above are required to submit a Stormwater Control Plan. Please use the Stormwater Control Plan template provided to facilitate timely review. Public Works staff will review the stormwater control plan during the plan check process utilizing the Post Construction Stormwater Requirements Checklist.
The San Luis Obispo County Low Impact Development Handbook provides guidance on designing stormwater management controls. Refer to the below FAQ for additional resources. The LID Plant Guidance for Bioretention provides guidance for appropriate plants and methods in LID areas.
Create a Post-Construction Plan
The Construction General Permit and the Central Coast Post-Construction Requirements mandate that applicants create an Operations and Maintenance Plan for any structural control measures that are installed to mitigate post-construction stormwater runoff.
Projects outside the Stormwater Management Area that enroll in the Construction General Permit must also submit an Operations and Maintenance Plan as a component of the site’s Stormwater Pollution Prevention Plan.
Projects within the County’s Stormwater Management Area must record an Operations and Maintenance Plan with the Department of Planning and Building. Please refer to post-construction stormwater management for additional information.
Stormwater Management During Construction
The Department of Planning & Building administers state and federal pollution prevention policies for stormwater runoff for all building permits, verifying that appropriate stormwater permits and plans are in place prior to the commencement of construction. Please refer to Stormwater Management During Construction for additional information.
Stormwater Management Inspections and Certification
The system design engineer must inspect the stormwater system utilizing the County's SWCP Construction Inspection Checklist or equivalent to ensure the system is in substantial conformance with the approved plans. In addition, the system design engineer must submit a certification prior to final of construction permits.
Who is eligible?
Anyone applying for a construction permit through the Planning and Building Department or an Encroachment Permit from Development Services.
Is there a charge for this service?
The cost for this service is factored into applicable construction permit fees and in some cases the actual cost via a checking and inspection agreement.
When and where is this service offered?
This service is available throughout the year during regular business hours except during scheduled holidays.
FAQS
Sites that disturb more than 1.0 acre or are part of a common plan of development must enroll for coverage. For more information about whether a site must enroll for coverage, please review the California Construction General Permit FAQs.
The following online resources provide guidance specific to implementing low impact development for stormwater in California or the Central Coast:
For more information on post-construction stormwater runoff management requirements and Low Impact Development please visit the Stormwater Management Post-Construction page. For more information on construction stormwater Best Management Practices and County requirements during construction, please visit the Construction Site Stormwater Management page.
The County’s online Land Use View application can help determine which standard applies based on the location of the project. To check the status of a property:
- Type the parcel number of the property into the ‘Search’ box in the upper right, then select the parcel information that appears on the bottom of the screen to highlight the parcel.
- Locate the ‘Filter Layers…’ box on the left hand side, type MS4 into the box, and press enter. Select the checkbox for ‘MS4 Coverage Areas’ that appears in the menu below to turn on the map layer.
If the parcel is covered by the MS4 Coverage Area, then the Central Coast Post Construction Requirements are applied. Parcels not included in the MS4 Coverage Area will be subject to the requirements of the California Construction General Permit.
Yes. The County of San Luis Obispo is required per Attachment 1, Section D of the Central Coast Post Construction Stormwater Management Requirements to field verify that Structural Water Quality treatment, Runoff Retention, and/or Peak Management controls were constructed in accordance with said requirements.
