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This feature class satisfies the Guidelines for Defining Areas Subject to Zero Net Use by combining Critical Watershed Areas with Class 4 Groundwater Availability areas.
Background
ADU Code Text (Sec. 26-88-060):
ADUs with water provided by a groundwater well or spring in Class 3 and 4 Groundwater Availability Zones shall be limited as follows:
In Class 3 areas, ADUs shall be permitted only if:
The domestic water source is located on the subject lot, or a mutual water source is available; and
Groundwater yield is sufficient for the existing and proposed use, pursuant to Section 7-12 of the Sonoma County Code.
In Class 4 areas, or critical habitat areas as identified by the County and informed by State or Federal agency publications of critical habitat areas for fisheries, an ADU shall be permitted only if:
Both requirements for Class 3 areas, above, are met; and
The ADU can be shown to have a net zero increase in water usage on the lot, following the most recent guidance, policy, or procedure adopted by the Director of Permit Sonoma.
Final Zero Net Use Areas in this feature class are defined as follows:
Class 4 groundwater availability areas as defined in the Sonoma County General Plan (i.e. Class 4 polygon in the Groundwater Availability feature class)
in addition to
Critical Watershed Areas of 2015 drought regulated watersheds as defined through “2015 DROUGHT-RELATED EMERGENCY REGULATION REQUIRING ENHANCED WATER CONSERVATION AND ADDITIONAL WATER USER INFORMATION FOR THE PROTECTION OF SPECIFIC FISHERIES IN TRIBUTARIES TO THE RUSSIAN RIVER” (https://www.waterboards.ca.gov/waterrights/water_issues/programs/drought/emergency_regulation_russianriver2015.html)
Source Information:
(2) The State Board recognizes that the upper portion of each of the watersheds listed in (c)(1) is the most critical for mid- to late-summer rearing of state and federally threatened and endangered salmon and steelhead species. These upper portions are defined as:
(A) On Mark West Creek, the portion of the watershed upstream of the confluence with an unnamed tributary (the tributary flowing parallel to western Riebli Road) as defined by the Latitude/Longitude of 38.5066°N and 122.72607°W.
(B) On Mill Creek, the portion of the watershed upstream of the confluence with Felta Creek, and including Felta Creek, as defined by the Latitude/Longitude of 38.58098°N and 122.88306°W.
(C) On Green Valley Creek, the portion of the watershed upstream of the confluence with Atascadero Creek as defined by the Latitude/Longitude of 38.44841°N and 122.88697°W.
(D) On Dutch Bill Creek, the portion of the watershed upstream of the confluence with Tyrone Gulch as defined by the Latitude/Longitude of 38.44776°N and 122.99979°W.
Critical Watersheds Areas were defined as follows:
Critical Watershed Areas, a subset of Priority Watershed Areas, as designated by the California State Water Resources Control Board. Updated by State Water Board on June 4, 2015, and downloaded as shapefiles from their website: https://www.waterboards.ca.gov/waterrights/water_issues/programs/drought/docs/russian_river/.
On June 17, 2015, the State Water Board adopted an emergency regulation to help protect federal- and state-listed anadromous fish in four priority Russian River tributary watersheds (Dutch Bill Creek, Green Valley Creek, portions of Mark West Creek, and Mill Creek).
The Office of Administrative Law approved the emergency regulation and the emergency regulation went into effect on July 6, 2015. The emergency regulation is in effect for 270 days. The emergency regulation requires: (1) enhanced water conservation in critical areas of the four watersheds; and (2) information on water use if requested by the State Water Board. Dutch Bill Creek; Green Valley Creek; Mill Creek; and portions of Mark West Creek. The California Department of Fish and Wildlife and National Marine Fisheries Service have identified critical habitat for state- and federally-listed Central California Coast coho salmon (CCC coho salmon) and Central California Coast steelhead (CCC steelhead) in these four tributary watersheds.
The ongoing drought places CCC coho salmon and CCC steelhead in Russian River tributaries in a perilous situation, challenging the fishes ability to survive a fourth year of the worst drought in recorded California history. Swift action is necessary to protect their limited habitat and avoid extinction given the continuing dry conditions. The address lookup tool and maps are provided below to help landowners determine if their properties or water diversions are located in one of the four watersheds: Dutch Bill Creek, Green Valley Creek, Mill Creek, and portions of Mark West Creek. Critical Area: 1) All landowners are required to respond to any informational order(s) issued by the State Water Board, AND 2) all water users are subject to enhanced water conservation measures, unless their sole supply of water comes from a water provider whose supply is from a source outside of the four priority tributary watersheds. You can contact your water provider to determine whether the water they provide exempts you from the enhanced water conservation requirements of the emergency regulation.
The State Water Board's Drinking Water Supply Service Area Lookup Tool can be used to determine who the water supplier is for a certain area. Priority Watershed Area: All landowners are required to respond to any informational order(s) issued by the State Water Board. Water users within the priority watershed area, but outside of the critical area ARE NOT INITIALLY required to implement enhanced water conservation measures, but may be subject to the requirements at a later date if the Deputy Director extends the requirements to other portions of the four watersheds after consultation with the California Department of Fish and Wildlife or the National Marine Fisheries Service. Water users are encouraged to conserve water.
Groundwater Availability Areas feature class (EDIT_PRMD_ENG_WS_HYD_GRND_WTR) is defined as follows. This feature class uses only Class 4 Areas ("areas with low or highly variable water yield") and discards Class 1-3 Areas from the original Groundwater Availability Areas feature class:
The Groundwater Availability Areas (GWA) dataset represents four zones that identify water yield, natural recharge and/or major/marginal groundwater basins within the County of Sonoma.
Interpretation of Water Availability Map:
The Groundwater Availability project developed by Permit Sonoma GIS from the official source is the tool used by PRMD staff for site specific analysis of development proposals.
The following rules will be used by PRMD Staff in interpreting the map:
1) If a parcel is on a boundary between water availability areas PRMD staff will consider the parcel to be in the most restrictive water availability area. PRMD staff may consider the exact location of the proposed well in making their determination when strong evidence is presented that the well draws from a major groundwater basin or major recharge area.
2) In addition they may require special studies to verify water availability.
3) In cases where the proposed location of the water source is not on the same parcel as the building permit and/or is on property not owned by the applicant, the applicant must submit verification that water availability at the well site is sufficient for the project and that they have permanent control of or access to the water source.
Appeals:
An applicant may appeal the water availability determination of PRMD staff by submitting a Letter of Water Availability Appeal accompanied by proof that their water situation is different than shown on the map. That proof may consists of report or other data from a licensed professional utilizing data regarding geology, soils, well logs or other authoritative studies. These proposed amendments will follow the same process used for internal amendment proposals and if approved a LOMA will be processed.
Amending the Map:
As new or more detailed water availability data becomes available PRMD may amend the Official Water Availability Map. Amendments to the map may be initiated internally by PRMD staff due to new data being available form authoritative sources or by applicants in connection with specific projects. PRMD technical staff will evaluate map amendment proposals and if warranted generate an official Letter of Map Amendment. The LOMA will be approved by the Deputy Director for Planning and Engineering and transmitted to GIS staff. Assigned staff will update the official map and log the change into the Map Change Log.
Releated Resource: