Groundwater Availability Areas

The groundwater availability areas 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 PRMD's GIS section 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:
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.  In addition they may require special studies to verify water availability.

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.

Since the GIS data was developed for planning purposes and use in publication of maps and/or database creation, the data is for illustrative purpose only and is not suitable for parcel specific decision making. 

Therefore, the GIS data presented herein are approximations and further land development determination is at the discretion of the PRMD planning staff which may require a parcel specific site review (to draw parcel specific conclusions).

Creation methodology & resources:
1) refer to Data Quality - Attribute Accuracy tab for historical dataset modifications & by ActiveMap version release number
2) for ActiveMap Data Capture June 2010 [ver. 2.0.2], rectified dataset to Sonoma County boundary based on AM_PARCEL 04/01/2010 (modified to the border & validated topology)

Note:
The exhibits in the General Plan Resource Conservation Element (RC-2a-i) are the official, adopted Groundwater Availability Zones.