B. Description of Proposed Boundary Modification

1. Short Description

   The County of Marin is requesting an internal boundary modification that would extend the Sand Point Area Basin to include that portion of the Wilson Grove Formation Highlands Basin currently in Marin County. The new boundary would be the county line.
2. Type of basin boundary revision

   • Jurisdiction Internal
3. Provide a narrative overview of the boundary modification request and how the resulting modification would affect likelihood of sustainable management.

   The County of Marin is requesting modification of the Bulletin 118 defined Sand Point Area groundwater basin to incorporate the jurisdictional area of the County of Marin that is currently in the Wilson Grove Formation Highlands (Wilson Grove) groundwater basin. The County of Marin has coordinated with the local agencies in the Wilson Grove and Sand Point Area groundwater basins, as evident by the letters of support for the proposed modification. Modification of the Sand Point Area basin boundary to include the portion of Wilson Grove Formation Highlands that underlies Marin County will promote sustainable groundwater management by enabling the County, with jurisdiction over land and water use, to have oversight of one basin that will be within the County political boundary. The boundary modification will enhance the ability of Marin County to sustainably manage groundwater if that basin is elevated to medium priority.

   Attachment(s):

   Resolution Boundary Mod application.pdf (4.2MB) Uploaded on 09/20/2018 at 10:30AM
4. List of the existing basin(s)/subbasin(s) to be modified by this request

   • 1-059 WILSON GROVE FORMATION HIGHLANDS
   • 2-027 SAND POINT AREA
5. Provide the proposed name for the new basin(s) or subbasin(s)

   Sand Point Area

C. Initial Notification and Combination of Requests

1. Was an initial notification submitted to the Department?

   Yes
   List of submitted initial notification for the selected basin(s)/subbasin(s).

   Local Agency	Potential Basin(s)/Subbasin(s)
   	2-001 PETALUMA VALLEY , 1-059 WILSON GROVE FORMATION HIGHLANDS
   	1-059 WILSON GROVE FORMATION HIGHLANDS
   Marin County	1-059 WILSON GROVE FORMATION HIGHLANDS , 2-027 SAND POINT AREA

2. Does this application include a combination of requests?

   No

D. Required Documents for All Modifications

1. A copy of the statutory or other legal authority under which the requesting agency was created with specific citations to the provisions setting forth the duties and responsibilities of the agency.

Attachment(s):

• size: 2
• Legal Authority for Land Use.pdf (1.7MB) Uploaded on 09/20/2018 at 01:10PM
• Legal Authority for Land Use.pdf (1.7MB) Uploaded on 09/20/2018 at 01:19PM

2. A copy of the signed resolution adopted by the requesting agency formally initiating the boundary modification request process.

Attachment(s):

• size: 1
• Resolution Boundary Mod application.pdf (4.2MB) Uploaded on 09/20/2018 at 10:33AM

3. A map of adequate scale (no greater than 1:24,000; e.g., 1:10,000 is not acceptable) showing the proposed modified basin boundary in relation to the existing Bulletin-118 basin boundary and the local agencies that are within or bordering the existing and proposed basin.

Attachment(s):

• size: 3
• Proposed Sand Point GW Basin.pdf (811.1kB) Uploaded on 09/20/2018 at 10:34AM
• 5. NorthernMarinBasin.pdf (319.9kB) Uploaded on 10/04/2018 at 11:27AM
• 5. NorthernMarinBasin.zip (69.1kB) Uploaded on 10/04/2018 at 10:51AM

4. A GIS shapefile of the proposed modified groundwater basin boundaries. Download Existing B118 basin shape file | DWR Spatial Data Standards

Attachment(s):

• size: 1
• GIF File Wilson_SandPoint_MarinCounty_Final.zip (30.3kB) Uploaded on 09/20/2018 at 01:19PM

5. A GIS shapefile of the political boundaries of any affected or adjacent local agency. Download water agency shape file

Attachment(s):

• size: 1
• 5. NorthernMarinBasin.zip (69.1kB) Uploaded on 09/20/2018 at 01:20PM

6. Any information, if necessary, to enable DWR to satisfy the requirements of a responsible agency pursuant to the California Environmental Quality Act.

The proposed modification of the Sand Point and Wilson Grove Formation Highland groundwater basins boundary is not a Project as defined by CEQA in accordance with Section 15378(b)(5) of the CEQA Guidelines because the proposed boundary modification consists of organizational or administrative activities of governments that will not result in direct or indirect physical changes in the environment.

E. General Information

1. Describe the lateral boundaries of the alluvial aquifer or aquifers that form the groundwater basin and the definable bottom of the basin. The description must be in terms that are clear, definite, and sufficiently detailed to allow an authoritative map of the proposed basin boundaries to be plotted using the given description.

The Sand Point Area Groundwater Basin is bounded to the west, south and southwest by Tomales Bay. Tomales Bay is a geologic feature of high significance, as it delineates the north, northwest trending San Andreas Fault zone. The basin's northern boundary lies just south of Dillon Beach, and adjoins the Wilson Grove Formation Highlands basin. Thea eastern boundary extends inland a distance that varies from about ¼ mile in the south to just over 2 miles in the north. The northern and eastern basin boundaries approximate the contact between the alluvial deposits in the basin and the surrounding bedrock. Holocene beach sands and Latest Pleistocene to Holocene dune sands are predominant basin deposits. The Wilson Grove Formation Highlands Groundwater Basin is bounded by Chileno Valley on the south, Bodega Bay on the west, and the Tolay Fault on the east. The contact between the Franciscan and Wilson Grove Formation defines the Basin boundary on the north. The Bloomfield Faults bisects the Basin from north to south. Several streams drain the basin and join to form Estero Americano Creek which runs from east to west through the basin. Most of the smaller tributaries flow south and west to join the creek before it enters Bodega Bay. The cities of Sebastopol and Forestville are located in the north of the basin and the city of Petaluma is located in the south.

F. Notice and Consultation

1. List all local agencies and public water systems affected by the basin(s) modification request.

County of Marin Estero Mutual Water Company Coast Springs/Cal Water North Marin Water District Sonoma County Sonoma County Water Agency City of Petaluma City of Sebastopol Tomales Village Community Service District

2. Explain the methods used to identify interested local agencies and public water systems in the affected basin(s):

Consulted with Petaluma Valley GSA, Sonoma County Water Agency , and Sonoma and Marin Counties. Reviewed existing maps of agency boundaries, established GSAs, and 2018 Basin Prioritization. Contacted CDPH for list of small drinking water systems.

Attachment(s):

• size: 1
• Public Notice Groundwater Boundary Change.pdf (150.9kB) Uploaded on 09/20/2018 at 10:44AM

3. Provide information regarding the nature of consultations with affected or interested agencies. Attach and cite any copies of correspondences with local agencies and public water systems and/or any other persons or entities consulted.

A public hearing was noticed by the Marin County Board of Supervisors. Additionally, the attached public notice was sent to all the agencies, as well as small water systems. Blue Mountain Center Piazzi Building Shoreline School District Bus Garage Tomales Elementary & Middle School Tomales High School William Tell House

Attachment(s):

• size: 1
• Public Notice Groundwater Boundary Change.pdf (150.9kB) Uploaded on 09/20/2018 at 10:45AM

4. Provide a summary of all public meetings at which the proposed boundary modification was discussed or considered by the requesting agency. Attach and cite any copies of agendas and notices published.

A public hearing of the Marin County Board of Supervisors was held on September 18 to approve the Resolution to apply for the proposed Basin Boundary Modification. The hearing was noticed to the public at least 10 days prior to the hearing date as is required for all public meetings. There was no opposition voiced nor any written opposition received by the Board members. Please see the attached approved Resolution.

Attachment(s):

• size: 1
• Resolution Boundary Mod application.pdf (4.2MB) Uploaded on 09/20/2018 at 10:46AM

5. Attach a copy of all comments regarding the proposed boundary modification received by the requesting agency and a summary of any responses made by the requesting agency.

Please see the attached letters of support. As noted in #4, no written or verbal opposition was received.

Attachment(s):

• size: 6
• Letter of Support SonomaCounty.pdf (118.7kB) Uploaded on 09/20/2018 at 10:51AM
• Petaluma Letter of Support for Marin County.pdf (224.4kB) Uploaded on 09/20/2018 at 10:51AM
• Support Ltr Estero Mutual Water.pdf (276.2kB) Uploaded on 09/20/2018 at 10:51AM
• Support Ltr North Marin Water.pdf (338.7kB) Uploaded on 09/20/2018 at 10:52AM
• Support Ltr Tomales Vil Community.pdf (314.4kB) Uploaded on 09/20/2018 at 10:52AM
• Support Ltr Marin Resource.pdf (370.9kB) Uploaded on 09/20/2018 at 11:06AM

G. General Existing Groundwater Management

1. Explain how sustainable groundwater management exists or could likely be achieved in the basin:

The Wilson Grove Formation Highlands Groundwater Basin was deemed a low priority basin so a Sustainable Groundwater Management Agency and Plan were not developed. Since the Basin has recently been deemed medium priority, the Basin would be managed by many jurisdictions including Marin County, Sonoma County, City of Petaluma, and the City of Sebastopol. The proposed modification to change the Sand Point Area Basin boundary to encompass the portion of the Wilson Grove Formation Highlands Basin underlying Marin County would simplify the groundwater management by having only one responsible jurisdiction managing the groundwater in Marin County.

2. Explain how the proposed boundary modification would affect the ability of adjacent groundwater basins to sustainably manage groundwater in those groundwater basins.

The Cities of Petaluma and Sebastopol are also proposing basin boundary modifications of the Wilson Grove Formation Highlands Groundwater Basin. If the cities and the Marin County are successful, the Wilson Grove Formation Highlands Basin will be managed by a single jurisdiction, Sonoma County.

3. Provide a historical summary of the sustainable management of groundwater levels in the proposed basin(s) or subbasin(s).

There is little data about the Wilson Grove Formation Highlands Groundwater Basin hydrogeology. However, the groundwater levels in the Basin appear to be stable as there were no level declines between 2014 and 2018. There is no published information regarding the Sand Point Area Groundwater Basin.

4. Discuss potential impacts to state programs resulting from the proposed boundary modification, including, but not limited to, the California Statewide Groundwater Elevation Monitoring (CASGEM), Groundwater Management Plans developed pursuant to AB 3030, Groundwater Sustainability Plans developed pursuant to the Sustainable Groundwater Management Act, any applicable state or regional board plans, and other water management and land use programs.

EHS is the designated groundwater monitoring entity for DWR?s California Statewide Groundwater Elevation Monitoring Program (CASGEM) for the groundwater basins within the County. In April 2018, EHS submitted our current CASGEM Plan to DWR. While this plan will be updated if DWR approves the boundary request, the monitoring sites and schedule will remain the same. Well levels will be measured twice-a-year in the newly configured Sand Point Area Basin. Information gathered from our monitoring will provide valuable baseline information to the public, local water users, and the State to help manage the groundwater resources in Marin.

H. Local Support

1. Provide any evidence that sufficient information was provided to affected agencies and systems regarding the proposed boundary modification.

Letters of support are included in the response to #5. The letters of support are from: North Marin Water District Sonoma County and Sonoma County Water Agency City of Petaluma Marin Resource Conservation District Estero Mutual Water Company Tomales Village Community Services District

Attachment(s):

• size: 6
• Letter of Support SonomaCounty.pdf (118.7kB) Uploaded on 09/20/2018 at 10:59AM
• Petaluma Letter of Support for Marin County.pdf (224.4kB) Uploaded on 09/20/2018 at 10:59AM
• Support Ltr Estero Mutual Water.pdf (276.2kB) Uploaded on 09/20/2018 at 10:59AM
• Support Ltr North Marin Water.pdf (338.7kB) Uploaded on 09/20/2018 at 10:59AM
• Support Ltr Tomales Vil Community.pdf (314.4kB) Uploaded on 09/20/2018 at 10:59AM
• Support Ltr Marin Resource.pdf (370.9kB) Uploaded on 09/20/2018 at 11:04AM

2. Provide a list of all affected agencies and affected systems that submitted comments and/or documents in support or opposition to the proposed boundary. The agency submitting their support or opposition for a boundary modification must provide a copy of a resolution formally adopted by the decision-making body of the affected agency or system or a letter signed by an executive officer or other official with appropriate delegated authority who represents the agency or system. Attach copies of the resolution and/or signed letter detailing the support or opposition submitted.

Letters of Support were received by the affected water systems: Estero Mutual Water Company; North Marin Water District; Marin Resources Conservation District; Tomales Village Community Service District.

3. Provide any evidence that rebuts any opposition to the proposed boundary modification.

There is no known opposition to this proposed boundary modification. None was voiced at the Board of Supervisors? meeting on September 18, 2018 nor has any written correspondence in opposition been received.

I. Hydrogeologic Conceptual Model

1. Principal aquifer units within requested basin.
2. Lateral boundaries of the proposed basin, including:
   1. Geologic features that significantly impede or impact groundwater flow.
   2. Aquifer characteristics that significantly impede or impact groundwater flow.
   3. Significant geologic and hydrologic features and conditions of the principle aquifer units, as appropriate, including information regarding the confined or unconfined nature of the aquifer, facies changes, truncation of units, the presence of faults or folds that impede groundwater flow, or other groundwater flow restricting features.
   4. Key surface water bodies, groundwater divides and significant recharge sources.
3. Recharge and discharge areas within the basin.
4. Definable bottom of the basin or subbasin.

The department may waive this requirement for an internal boundary modification if the requesting agency is able to demonstrate that the proposed boundary modification is unlikely to affect sustainable groundwater management.

This modification does not introduce any new hydrologic or geologic features that would impact sustainable groundwater management in any of the affected basins. Attached is the a study of groundwater basin adjacent to the Wilson Grove Highland Basin, in neighboring Sonoma County.

Attachment(s):

• size: 2
• NC-5_SRP_SonomaCoWaterAgency_GWMP_2014.pdf (31.6MB) Uploaded on 10/04/2018 at 11:28AM
• SGMA_Pet_Son_SR_GWB_WtrShds_NewBasins.pdf (599.4kB) Uploaded on 10/04/2018 at 10:57AM

L. Technical Studies for All Jurisdictional Modifications

1. A water management plan that covers or is in the immediate vicinity of the proposed basin or portion of the proposed basin and satisfies the requirement of Water Code sections 10753.7(a) or 10727 by attaching one of the following:
   1. An adopted groundwater management plan, a basin wide management plan, or other integrated regional water management program or plan.
   2. Management pursuant to an adjudication action.
   3. One or more technical studies that cover the relevant portion of a basin or subbasin and adjacent areas.

Attachment(s):

• size: 1
• Technical Studies.pdf (17.2kB) Uploaded on 09/20/2018 at 01:36PM

2. A statement of the existing and planned coordination of sustainable groundwater management activities and responsibilities where required.

A sustainable groundwater management agency will be formed and a plan will be developed to manage groundwater in the proposed Sand Point Area Groundwater Basin in the future. This will all be dependent on the outcome of the proposed basin boundary modification.