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California Construction Stormwater Permit (6-CA-b)

Information current as of 2022
In California, a developer may need a General Permit for Discharges of Stormwater Associated with Construction Activities (General Permit) from the California State Water Resources Control Board (State Water Board) for stormwater discharges from construction projects that result in a land disturbance of one (1) or more acres or are part of a larger plan of common development that will disturb one (1) or more acres. General Permit, § I(B)(18)-(19); 40 C.F.R. § 122.26(a)(1), a(9)(i), (b)(14)(x), (b)(15)(i).

The State Water Board also regulates Linear Underground/Overhead Utility Projects (LUPs) through the General Permit program, though the General Permit separates the requirements for such projects from traditional construction activities. General Permit, § I(B)(18-19, 21); General Permit, § II(A)-(B). The conditions for permit coverage and the risk determination criteria are different for LUPs and traditional construction projects, but the application process is largely the same. For a complete list of activities that are covered under the state’s General Permit, see General Permit, § I(B)-(C).

The State Water Board reviews and oversees the distribution of permit applications. Construction General Permit Fact Sheet, p. 12. Although the State Water Board does not issue Individual NPDES permits, the Regional Water Quality Control Boards (RWQCBs) have the authority to require a developer otherwise covered under the General Permit to apply for an Individual Permit or apply for coverage under a more specific General Permit. RWQCBs may take such action if they determine that the statewide General Permit does not provide adequate assurance of the protection of water quality or that there is a site-specific reason to require an individual permit. Construction General Permit Fact Sheet, p. 7. In addition, the RWQCBs are responsible for the implementation and enforcement of the General Permit. General Permit, § I(N).



Construction Stormwater Permit Process


6-CA-b.1 to 6-CA-b.2 – Is the Project Exempted under EPA’s Small Construction Rainfall Erosivity Waiver?

Under EPA’s Stormwater Phase II Final Rule, if a project will affect between one and five acres, developers may obtain a waiver from the General Permit if the construction will not have adverse water quality impacts. In order to obtain the waiver, the developer must send a Notice of Intent (NOI) and Sediment Risk form through the State Water Board’s Stormwater Report Tracking System (SMARTS), certifying that the construction activity will occur only when the rainfall erosivity factor is less than five. For more information, see General Permit, § II(B)(7); Construction General Permit Fact Sheet, p. 11.

6-CA-b.3 to 6-CA-b.5 - Is the Project in the Lake Tahoe Hydrologic Unit?

The Lahontan RWQCB (RWQCB 6SLT) has adopted its own permit to regulate stormwater discharges from construction activity in the Lake Tahoe Hydrologic Unit. Developers in this watershed must submit PRDs to the SMARTS system based on the Lahontan RWQCB Order No. R6T-2011-0019 as opposed to the State Water Resources Control Board Order No. 2009-009-DWQ. Upon receipt of the appropriate PRDs, the Lahontan RWQCB determines whether the discharges comply with the requirements found in the order. See the Lahontan RWQCB Order No. R6T-2011-0019, p. 10.

6-CA-b.6 – Determine Risk Level

According to the State Water Resources Control Board Order No. 2009-009-DWQ, the developer must “calculate the site’s sediment risk and receiving water risk during periods of soil exposure (i.e. grading and site stabilization) and use the calculated risks to determine a Risk Level using the methodology in Appendix 1 [of the order].” The Risk Level is determined by two elements: the project sediment risk and the receiving water risk. The Risk Level is then used to determine what BMPs must be used and what requirements must be complied with.

  • Risk Level 1 requires compliance with Attachment C of the General Permit;
  • Risk Level 2 requires compliance with Attachment D; and
  • Risk Level 3 requires compliance with Attachment E.

The risk determination process and the Risk Level should be documented in a Risk Assessment, which must be submitted along with the other PRDs. See State Water Resources Control Board Order No. 2009-009-DWQ, section VII; Construction General Permit Fact Sheet, p. 27-29. If an RWQCB disagrees with a Risk Level, it may order the developer to re-evaluate it. The RWQCB may also terminate General Permit coverage if a Risk Level cannot be agreed upon. See State Water Resources Control Board Order No. 2009-009-DWQ, § XV.


6-CA-b.7 – Permit Registration Documents (PRDs)

Developers whose construction activities are subject to the General Permit must submit Permit Registration Documents (PRDs) to the State Water Board, demonstrating compliance with the General Permit’s requirements, including Best Management Practices (BMPs) and Numeric Action Levels (NALs) that are designed to achieve the minimum federal standards for construction stormwater runoff. Failure to do so is a violation of the CWA. See the General Permit Fact Sheet p. 2-3. Note that requirements in the General Permit related to Numeric Effluent Limitations (NELs) have been invalidated by the Superior Court of California. As a result, while the developer must still comply with the Best Management Practices in the Construction General Permit, specific requirements for turbidity and pH NELs have been removed (except for those related to an Active Treatment System (ATS)). For more information, see the Construction General Permit Fact Sheet, p. 13-14; California Building Industry Association et al. v. State Water Resources Control Board.

In order to comply with the General Permit, the developer must electronically file all required PRDs, Notice of Terminations (NOTs), changes of information, annual reporting, and other compliance documents via the SMARTS website. See State Water Resources Control Board Order No. 2009-009-DWQ, § I(D). The following documents are required PRDs (if applicable):

  • Notice of Intent: The NOI informs RWQCBs of the developer’s intent to commence construction within their jurisdiction. If a single project traverses more than one RWQCB’s jurisdiction, a complete Notice of Intent package (Notice of Intent, site map, and fee) must be filed for each RWQCB. See the California Construction Storm Water Program Website.
  • Site Map: The site map must include the construction site perimeter, existing and proposed buildings, lots, roadways, stormwater collection and discharge points, general topography both before and after construction, and drainage patterns across the project. See State Water Resources Control Board Order No. 2009-009-DWQ, Attachment B.
    • All pollutants and their sources, including sources of sediment associated with construction, construction site erosion and all other activities associated with construction activity are controlled;
    • Where not otherwise required to be under a Regional Water Board Permit, all non-stormwater discharges are identified and either eliminated, controlled, or treated;
    • Site BMPs are effective and result in the reduction or elimination of pollutants in stormwater discharges and authorized non-stormwater discharges from construction activity to the Best Available Technology Economically Feasible (BAT) / Best Conventional Pollutant Control Technology (BCT) standard;
    • Calculations and design details as well as BMP controls for site run-on are complete and correct; and
    • Stabilization BMPs installed to reduce or eliminate pollutants after construction are completed.

The Qualified SWPPP Developer must include information in the SWPP that supports the conclusions, selections, use and maintenance of BMPs in order to demonstrate compliance with the requirements of the General Permit. As stated above, the General Permit requirements vary based on the risk level. For more information regarding General Permit requirements, see the State Water Resources Control Board Order No. 2009-009-DWQ, Attachments C, D, and E. For information regarding General Permit requirements for LUPs, see the State Water Resources Control Board Order No. 2009-009-DWQ, Attachments A.

  • Post-Construction Water Balance Calculator: If the project is non-linear and in an unincorporated area of California, the developer must complete the Post-Construction Water Balance Calculator in accordance with the instructions found in the State Water Resources Control Board Order No. 2009-009-DWQ, Appendix 2.
  • Active Treatment System Design Document and Certification: An ATS is “a treatment system that that employs chemical coagulation, chemical flocculation, or electrocoagulation to aid in the reduction of turbidity caused by fine suspended sediment.” See the State Water Resources Control Board Order No. 2009-009-DWQ, Appendix 5. An ATS may be necessary when traditional erosion and sediment controls do not effectively control accelerated erosion, when stormwater discharges leaving the site may cause or contribute to an exceedance of a water quality standard, or when site constraints inhibit the implementation of traditional BMPs. The developer may also elect to use an ATS. See Construction General Permit Fact Sheet, p. 35-36. If an ATS is used, the developer must submit its design system, supporting documentation, and proof that the ATS was designed by a qualified ATS design professional. See the State Water Resources Control Board Order No. 2009-009-DWQ, Attachment B. For more information regarding ATS requirements, see the State Water Resources Control Board Order No. 2009-009-DWQ, Attachment F.


6-CA-b.8 – Mail Annual Fee to the State Water Board

The developer must mail the annual fee to the State Water Board contemporaneously with the submission of the PRDs. See the State Water Resources Control Board Order No. 2009-009-DWQ, § II(B)(3). Annual fees are calculated based upon the total area of land to be disturbed not the total size of the acreage owned. However, the calculation includes all acres to be disturbed during the duration of the project. For example, if ten acres are scheduled to be disturbed the first year and ten in each subsequent year for five years, the annual fees would be based upon 50 acres of disturbance. The State Water Board will evaluate adding acreage to an existing Permit Waste Discharge Identification (WDID) number on a case-by-case basis. In general, any acreage to be considered must be contiguous to the permitted land area and the existing SWPPP must be appropriate for the construction activity and topography of the acreage under consideration. As acreage is built out and stabilized or sold, the Change of Information (COI) form enables the applicant to remove those acres from inclusion in the annual fee calculation. Checks should be made payable to the State Water Board.

The Annual fees are established through regulations adopted by the State Water Board. The total annual fee is the current base fee plus applicable surcharges for all construction sites submitting an NOI, based on the total acreage to be disturbed during the life of the project. Annual fees are subject to change by regulation.

Dischargers that apply for and satisfy the Small Construction Erosivity Wavier requirements must pay a fee of $200.00 plus an applicable surcharge. See the State Water Resources Control Board Order No. 2009-009-DWQ, Attachment B.

6-CA-b.9 – Waste Discharger Identification Number

Once the State Water Board receives the annual fee and all of the PRDs, SMARTS automatically assigns a Waste Discharger Identification Number (WDID). After the SMARTS issues the WDID, the developer is covered under the General Permit. See the State Water Resources Control Board Order No. 2009-009-DWQ, § II(B)(5). Construction without a WDID is a violation of the CWA.


6-CA-b.10 – Notice of Termination and Associated Documents

After the developer completes construction, the developer must file a Notice of Termination (NOT), a final site map, and photos through the SMARTS system within 90 days. The NOT must include evidence and a certification establishing that the following conditions have been met:

  • For purposes of “final stabilization,” the site will not pose any addition sediment discharge risk than it did prior to the commencement of construction activity;
  • There is potential for construction-related stormwater pollutants to be discharged into site runoff;
  • Final stabilization has been reached;
  • Construction materials and wastes have been disposed of properly;
  • Compliance with the Post-Construction Standards in Section XIII of the See the State Water Resources Control Board Order No. 2009-009-DWQ has been demonstrated;
  • Post-construction stormwater management measures have been installed and a long-term maintenance plan has been established; and
  • All construction-related equipment, materials and any temporary BMPs no longer needed are removed from the site.

See the State Water Resources Control Board Order No. 2009-009-DWQ, section II(D)(1).

In addition, the developer must demonstrate that the “final stabilization” condition is attained by one of the methods listed in the State Water Resources Control Board Order No. 2009-009-DWQ, section II(D)(3). If the above conditions are not met, coverage under the General Permit will continue and the developer will continue to be billed. See the State Water Resources Control Board Order No. 2009-009-DWQ, § II(D).


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