Two definitions of the PRGWB boundary
  1. “Bulletin 118 Boundary” - As defined by the California Department of Water Resources (DWR) in Bulletin 118 and used in the Paso Robles Subbasin Groundwater Sustainability Plan (GSP) per California Sustainable Groundwater Management Act (SGMA) requirements.

  2. “Fugro Boundary” - As defined in the County Code, Land Use and Construction and Building Ordinances, adopted by the County Board of Supervisors prior to SGMA, based on the 2002 study by Fugro West, Inc. and Cleath and Associates.

The County is proposing amendments to the County Code to update the PRGWB boundary in the Land Use Ordinance (Title 22) and Buildings and Construction Ordinance (Title 19) from the Fugro boundary to the Bulletin 118 boundary. See more detail below.

If your property is in the PRGWB per the Bulletin 118 definition,

then your property is subject to the management actions of the GSP, available at The management actions are discussed in GSP Chapter 9. The County has not yet taken any formal action to initiate the development of or otherwise authorize implementation of GSP management actions. 

If your property is in the PRGWB per the definition in Title 19 and Title 22,

then land divisions and General Plan Amendments that increase potential water demand are prohibited. All new construction and new irrigated crop production on your property is required to offset new water use at a 1:1 ratio. Existing development on your property may qualify to apply for a turf removal rebate ("cash for grass"), washing machine rebate, or free plumbing fixture retrofits.

No Land Divisions. No General Plan Amendments that Increase Water Demand.


Water Offset Fees for New Construction. New construction is required to pay water offset fees to fund projects to reduce existing water usage on other properties within the basin. Click the icon below to see the list of fees.

Agricultural Offset Application Required for New Commercial Irrigated Crops. New or expanded irrigated agriculture is required to apply for Agricultural Offset Clearance from the County Department of Planning & Building. Click the icon below to see application requirements.

Eligibility for Water Offset Programs. Water offset fees from new construction fund turf removal and plumbing retrofit projects on existing development per three options: 


  • Option #1: Individual residences, public facilities, and commercial uses may apply for up to a $6,000 rebate for turf removal ("Cash for Grass"); a $250 rebate to upgrade an old washing machine ("Washer Rebate Program"); and free replacement of up to two toilets, two showerheads, and two faucet aerators per property ("Plumbing Retrofit Program"). The application forms for these programs are available by clicking the icons below.

  • Option #2: Public facilities and commercial uses may apply for up to $10,000 to fund turf removal and plumbing retrofit projects that also create a public benefit. Projects need to quantify the anticipated water savings. If interested, email to start your project application.

  • Option #3: Any project requesting over $10,000 needs approval from the County Board of Supervisors.

If your property is in the PRGWB "area of severe decline" per the Title 22 definition,

then your property is subject to extra restrictions on new irrigated crop production. See "Agriculture Off-Set" above for more information. Also, if you are applying for a land use permit for cannabis activities, then you are required to offset water use at a 2:1 ratio rather than 1:1.


The County Land Use Ordinance currently defines the area of severe decline within the PRGWB as the area where groundwater elevation levels dropped 50 feet or more from Spring 1997 to Spring 2013, based on groundwater level contours generated using a computer-based contouring program, which are based on groundwater elevations measured at monitoring well locations. Proposed amendments to the Land Use Ordinance (see detail below) would change the definition to be based on Spring 1997 and Spring 2017 data.

Amendments to the PRGWB requirements in Title 19 and Title 22

On June 18, 2019, the Board directed staff to consider amendments to the Countywide Water Conservation Program. 

Phase 1 Amendments - Effective December 5, 2019 (Click here to see the updated ordinance.)

  • Eliminate off-site offsets.

  • Extend the termination date for the Paso Basin water offset requirements to January 1, 2022.

  • Include a water duty factor for hemp and supplementally irrigated dry cropland in the Agricultural Offset Program.

  • Create a process to determine water duty factors for crops not specified in the Agricultural Offset Ordinance.

Phase 1.5 Amendments - Planning Commission June 11, 2020. Board of Supervisors August 18, 2020.

  • Update the maps of the Paso Basin and the Area of Severe Decline (commonly known as the "red zone")

  • Create a fallowing registry

Blue = Unchanged. Green = Added. Orange = Removed.

To see the legend on the map:

  1. Click on Layers in the bottom left hand corner.

  2. Expand the Planning layer.

  3. Expand the Impacted Groundwater Basins layer. 

Planning Commission's Recommendation from June 11, 2020:

  1. Establish a fallowing program with an expiration date that is tied to implementation of regulations under the Groundwater Sustainability Plan.  Reach out to the Groundwater Sustainability Agencies to attempt to cooperate in the creation of such a program.

  2. Support staffs’ recommendation on amendments to de minimis language.

  3. Reject staffs’ recommendation on amendments to the mapping boundaries for the Area of Severe Decline until a study is conducted for the purpose of establishing and verifying the new boundary.

  4. Support staffs’ recommendation on amendments to the mapping boundaries for the Paso Robles Groundwater Basin and establish a process under which a landowner or the County could petition to be “removed from the boundary” for purposes of application of County land use regulations.

  5. Add ordinance language clarifying how properties that are bisected by the boundary of the Paso Robles Groundwater Basin or the area of severe decline boundary are subject to County regulations for these areas under the Agricultural Offset Ordinance.

Phase 2 Amendments - Pending environmental determination.

For Agricultural Offset Program in the Paso Basin

  • Expand the 5 AFY exemption to 25 AFY per site.

  • Extend the lookback period beyond 5 years.

  • Discuss re-allowing off-site offsets.

For Urban/Rural Water Offset Requirements

  • Revisit water offset fees and water usage assumptions in the Paso Basin.

  • Revisit the Paso Robles Groundwater Basin planning area standards prohibiting land divisions and General Plan Amendments.

  • Revisit the 1:1 offset requirement for the Nipomo Mesa.

To join the interest list to receive updates on the amendment process, please email Kylie Hensley at

© 2018 by County of San Luis Obispo Countywide Water Conservation Program.