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8-2-2 Guidelines for Net Zero Groundwater Use

Version 01/07/2020

Purpose

This document is intended to provide applicants and representatives with guidance on how to demonstrate that a development results in Net Zero groundwater use. As used herein, Net Zero means that groundwater use under post-project conditions is equal to or less than groundwater use under existing conditions, and the project complies with all applicable water use standards. These guidelines are intended for discretionary and ministerial projects.

Goal WR-2 of the Sonoma County General Plan specifies that groundwater should be managed as a valuable and limited shared resource. Certain areas of the County have been designated as water scarce, have declining groundwater levels, or have streams that are vulnerable to streamflow depletion attributed to groundwater extraction. In these areas, or where available information indicates impaired groundwater resources, standards requiring Net Zero may apply. For example, Net Zero is required for Accessory Dwelling Units in Class 4 Groundwater Availability Areas (Sec. 26-88-060). A Net Zero standard is also a water supply option for Commercial Cannabis Cultivation in Class 3 or 4 Groundwater Availability Areas (Sec. 26-88-254).

Discretionary projects subject to CEQA have the option to pursue Net Zero. A report demonstrating Net Zero may be used in lieu, or in support, of a hydrogeologic study that assesses impacts to groundwater resources. A project that meets the Net Zero standard is generally expected to have a less than significant impact on groundwater resources.

For discretionary projects, where there are concerns regarding potential seasonal environmental impacts from groundwater extraction, Net Zero may be applied during specific times of the year when groundwater pumping is more likely to lead to environmental impacts (e.g., depletion of stream base flows during the dry season).

Authority

Sonoma County General Plan, Water Resource Element Goals WR-2 and WR-4, Objective WR-4.1, WR-4.2, and WR-4.3, and Policies WR-2e, WR-4b, and WR-4f.

Procedure

An applicant may demonstrate that a project meets the Net Zero standard through Method 1 or Method 2 below. Method 1 is available to all projects, while Method 2 is available to development of accessory dwelling units where the project well is outside the Riparian Corridor Combining Zone. All projects must meet the minimum water use efficiency standards.

Demonstrating Net Zero may also be met through alternative means that are substantively equivalent to those outlined in this policy. Such alternative means proposals shall be considered on a case-by-case basis, and the determination of equivalence to the Net Zero standards shall be in the sole discretion of the Director.

Minimum Water Efficiency Standards Checklist:

  1. The design and operation of all proposed structures will achieve residential or commercial water efficiency and conservation standards for new construction as specified through the 2016 CA Green Code or most current version.
  2. All showerheads and toilets within all existing and proposed habitable spaces (including primary dwelling and accessory dwelling units) on the project parcel must meet current water efficiency standards defined in 2016 CA Green Code or most current version.
  3. The design and operation of all new or improved landscaped areas will meet or exceed standards in Sonoma County’s Water Efficient Landscape Ordinance (WELO).

Method 1. Net Zero Water Budget

Available to all types of development.

To demonstrate Net Zero through Method 1, submit a Net Zero report (Report) prepared by a Qualified Professional, as defined below, which documents how groundwater use under proposed project conditions will be less than or equal to groundwater use under existing site conditions. The Report will be reviewed and approved by the Director or designated approval body.  
Contents of the Report:

  1. Name and credentials of the Qualified Professional preparing the Report, consistent with the requirements outlined in the Definitions section below
  2. Project description
  3. Site Plan
  4. Description of how the project will meet the minimum water efficiency standards listed above
  5. Description of additional water conservation measures (e.g. water efficient landscape, ultra low flow toilet exchange)
  6. Summary of expected water use under existing and proposed conditions. A Water Supply and Use Assessment, prepared in accordance with the Permit Sonoma Water Supply and Use Assessment Guidelines, should be provided as an attachment to the Report
  7. Description of alternative water supplies that will be used (e.g. surface water, rainwater, recycled water, trucked water)
  8. Description of other measures to offset increased groundwater use (e.g. enhanced groundwater recharge, support of local water conservation program)
  9. Clear conclusion that the development meets the Net Zero groundwater use standard

Method 2. Prescriptive Compliance

Available only for Accessory Dwelling Units where the project well is outside of the Riparian Corridor Combining Zone.

To demonstrate Net Zero through Method 2, submit a Net Zero report prepared by a Qualified Professional. The Report will be reviewed and approved by the Director or designated approval body.

  1. Name and credentials of the Qualified Professional preparing the Report, consistent with the requirements outlined in the Definitions section below
  2. Project description
  3. Site Plan
  4. Description of how the project will meet the minimum water efficiency standards listed above
  5. WELO compliant landscape plan for the combined existing and proposed landscape areas specifying compliance with the prescriptive WELO compliance option (Sec. 7D3-9). Combined area of existing and proposed turf may not exceed 600 square feet. Existing areas of turf beyond the 600 square foot area must have the irrigation system removed and be tilled or otherwise destroyed.

Definitions

Director
Director of the Sonoma County Permit Resource Management Department or his/her designee
Qualified Professional
A professional geologist, engineer, or landscape architect, acting within the scope of their license. A qualified professional must hold a valid license in the State of California.
Water Efficient Landscape Ordinance (WELO)
County of Sonoma Water Efficient Landscape Ordinance (Chapter 7D3 of the Sonoma County Code)

Approved By

Approved By: Tennis Wick, Director

Reviewed By Department Manager:  John Mack, Division Manager

Reviewed By County Counsel:  Christa Shaw, Deputy County Counsel IV

Lead Author:  Robert Pennington, Professional Geologist

Contact Information

Contact Planning by Phone
Monday – Friday
10:00 AM – 12:00 PM
1:00 PM – 3:00 PM
Address
2550 Ventura Avenue
Santa Rosa, CA 95403
38.465074, -122.723705

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