B. Description of Proposed Boundary Modification

1. Short Description

   A boundary modification to merge a portion of the Cosumnes Subbasin into the Eastern San Joaquin
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 current location of the subbasin boundary splits the North San Joaquin Water Conservation District (NSJWCD) into both the Cosumnes and the Eastern San Joaquin subbasins. NSJWCD encompasses the entire area of the Cosumnes Subbasin within San Joaquin County. The burden of providing sustainable groundwater management in two subbasins, and resultant need for two GSP's and double the reporting effort, would tax the very limited resources of this small district. NSJWCD has surface water delivery facilities in both subbasins with limited water rights from the Mokelumne River. Allocation of this surface water into two different subbasins will likely lead to conflict between the two GSP's. Historically, groundwater management within the Cosumnes Subbasin has occurred separately with a split at the San Joaquin/Sacramento County line. Existing groundwater management plans are split north and south of the County line with the Cosumnes Subbasin portion within San Joaquin County included in the plan for the Eastern San Joaquin Subbasin. The proposed boundary modification will allow NSJWCD to efficiently allocate their resources and effectively manage the groundwater basin within their area enhancing their ability to achieve sustainability. The boundary modification will not effect the ability and likelihood for sustainable management of the remaining portions of the Cosumnes subbasin as the area historically has essentially been managed independently of the San Joaquin County portion.

   Attachment(s):
4. List the existing basin(s)/subbasin(s) to be modified by this request

   • 5-022.01 SAN JOAQUIN VALLEY - EASTERN SAN JOAQUIN
   • 5-022.16 SAN JOAQUIN VALLEY - COSUMNES
5. Provide the proposed name for the new basin(s) or subbasin(s)

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)
   Eastern San Joaquin County Groundwater Basin Authority	5-022.16 SAN JOAQUIN VALLEY - COSUMNES , 5-022.01 SAN JOAQUIN VALLEY - EASTERN SAN JOAQUIN
   Northern Delta GSA	5-021.65 SACRAMENTO VALLEY - SOUTH AMERICAN , 5-022.01 SAN JOAQUIN VALLEY - EASTERN SAN JOAQUIN , 5-021.66 SACRAMENTO VALLEY - SOLANO
   Lathrop City Of	5-022.15 SAN JOAQUIN VALLEY - TRACY , 5-022.01 SAN JOAQUIN VALLEY - EASTERN SAN JOAQUIN
   	5-021.66 SACRAMENTO VALLEY - SOLANO , 5-021.65 SACRAMENTO VALLEY - SOUTH AMERICAN , 5-022.01 SAN JOAQUIN VALLEY - EASTERN SAN JOAQUIN
   Sloughhouse Resource Conservation District	5-021.65 SACRAMENTO VALLEY - SOUTH AMERICAN , 5-022.16 SAN JOAQUIN VALLEY - COSUMNES
   Omochumne-Hartnell Water District	5-021.65 SACRAMENTO VALLEY - SOUTH AMERICAN , 5-022.16 SAN JOAQUIN VALLEY - COSUMNES
   	5-022.16 SAN JOAQUIN VALLEY - COSUMNES
   Omochumne-Hartnell Water District	5-021.65 SACRAMENTO VALLEY - SOUTH AMERICAN , 5-022.16 SAN JOAQUIN VALLEY - COSUMNES

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):

• GBA JPA.pdf (1.7MB) Uploaded on 03/23/2016 at 09:09AM

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

Attachment(s):

• Board Order #B-16-1_Approve Submission of Basin Boundary Modification Request_03142016.pdf (1.2MB) Uploaded on 03/17/2016 at 02:07PM

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):

• Proposed Eastern San Joaquin Groundwater Subbasin.pdf (6.5MB) Uploaded on 03/18/2016 at 01:12PM

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

Attachment(s):

• Proposed_ESJ.zip (310.1kB) Uploaded on 03/16/2016 at 09:01AM

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

Attachment(s):

• Water_Agencies_State_File.zip (547.5kB) Uploaded on 03/18/2016 at 02:06PM

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 subbasin boundary modification does not qualify as a project under CEQA.

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 boundaries as described in Bulletin 118 for the Cosumnes and Eastern San Joaquin Subbasins will be modified by moving the boundary north from the Mokelumne River to the San Joaquin County line. The new boundaries for the subbasins is described below: A. Cosumnes Subbasin: The Cosumnes Subbasin is defined by the areal extent of the unconsolidated to semiconsolidated sedimentary deposits that are bounded on the north and west by the Cosumnes River, on the south by the San Joaquin County Line and the Mokelumne River, and on the east by consolidated bedrock of the Sierra Nevada Mountains. B. Eastern San Joaquin Subbasin: The Eastern San Joaquin Subbasin is defined by the areal extent of the unconsolidated to semiconsolidated sedimentary deposits that are bounded by the San Joaquin County Line and the Mokelumne River on the north and northwest; San Joaquin River on the west; Stanislaus River on the south; and consolidated bedrock on the east. BASIN HYDROGEOLOGY Geologic formations within the Central Valley and San Joaquin County are generally grouped as either east-side or west-side formations based on their location relative to the San Joaquin River, and the source of the sedimentary material of which they are composed. Generally, Eastside formation material originates in the Sierra Nevada and Westside formation material originates in the Coastal Ranges. The most important fresh water-bearing formations in Eastern San Joaquin County are the Mehrten, Laguna, Victor, and alluvial deposits. The formations are described below. Mehrten The Mehrten Formation is considered the oldest significant fresh water-bearing formation within Eastern San Joaquin County. It is exposed in the eastern most portion of the county, and slopes steeply from 90 to 180 feet per mile reaching a depth of 800 to 1000 feet and a thickness of 400 to 600 feet in the Stockton ands, and gravels, the formation is often subdivided into upper and lower units. The upper unit is reported to contain finer grained deposits (black sands interbedded with brown-to-blue clay) and the lower unit consists of dense tuff breccia (Page, 1986). Consequently, groundwater is reported to be semi-confined in the Stockton area. The Mehrten Formation has moderate to high permeability where black sands occur. (DWR, 1967, Brown & Caldwell, 1985) Laguna The Laguna Formation outcrops in the northeastern part of the County and dips at 90 feet per mile (DWR, 1967), and reaches a maximum thickness of 1,000 feet. It consists of discontinuous lenses of unconsolidated to semi-consolidated sand and silt with lesser amounts of clay and gravel. The Laguna Formation is moderately permeable with some reportedly highly permeable coarse-grained beds and generally unconfined, but semi-confined conditions probably exist locally. Some studies have suggested that an extensive aquitard, namely the Corcoran Clay, extends into the Laguna Formation or separates the Laguna and Mehrten Formations (Brown & Caldwell, 1985). Victor The Victor Formation is of Holocene to Pleistocene age and consists primarily of stream deposited unconsolidated gravel, sand, silt, and clay. Coarse sands and gravels are found to the east, and sands, silts and clays towards the west. This formation is generally more permeable than underlying formations, and groundwater is typically unconfined. (CDM, 2001) Alluvial/Stream channel deposits Stream channel deposits are found along major stream and river courses within the study area. Generally they consist of unconsolidated gravel and coarse sand with high permeability. GROUNDWATER FLOW DIRECTION Groundwater contours for the Eastern San Joaquin Basin show a groundwater cone of depression east of the City of Stockton. Regional groundwater flows converge from all directions toward this depression. Groundwater flow in the area to be added flows north from the Mokelumne River to a small depression near the Countyline. see attached Report for maps

Attachment(s):

• Groundwater Report Fall 2015.pdf (3.4MB) Uploaded on 03/18/2016 at 03:59PM

F. Notice and Consultation

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

See attached file

Attachment(s):

• basin boundary revision interested parties.xlsx (22.9kB) Uploaded on 03/17/2016 at 02:13PM

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

The list of interested parties was developed from the Eastern San Joaquin County Groundwater Basin Authority mailing list, the Department of Water Resources website and general searches through the internet.

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.

The basin boundary modification proposal was discussed extensively at open public meetings with deliberate actions taken by the GBA with regards to its preparation and submittal. The North San Joaquin Water Conservation District covers all lands within the San Joaquin County portion of the Cosumnes Basin and adopted a resolution on August 31, 2015 requesting the GBA to undertake the basin boundary modification request. Prior to preparation of the basin boundary modification, staff was directed by the Eastern San Joaquin Region Sustainable Groundwater Management Act Workgroup and the GBA Board to explore the feasibility of making a basin boundary request and the level of effort required to provide the information required by DWR. There were a number of informal conversations with stakeholders in the Cosumnes Subbasin including the Southeast Sacramento County Agricultural Water Authority (Mike Wackman), Darrell Eck (Sacramento County), Amador Water Agency (Gene Mancebo) and Amador County (Mike Israel). What was explained was the nature of the possible request to include the San Joaquin County portion of the Cosumnes Basin in the Eastern San Joaquin Subbasin. One of the points raised was the previous boundary in DWR Bulletin 118-80 for the Eastern San Joaquin Subbasin actually coinciding with the San Joaquin County Line, which is Dry Creek; however, the Bulletin 118-80 boundary also extended into Amador County along what appears to be Jackson Creek. Clarifying this point with Amador County was suggested by DWR North Central District Staff on December 2, 2015 at a meeting held in West Sacramento. Amador County indicated they were not interested in being included in the GBA's basin boundary request citing concerns over being included in the critically overdrafted Eastern San Joaquin Subbasin. Based on the informal outreach done and an exploration of DWR's justification requirements, staff recommended to the GBA Board of Directors on January 13, 2016 that the Basin Boundary Modification request be compiled for including the portion the Cosumnes Subbasin within San Joaquin County in the Eastern San Joaquin Subbasin. The request excludes any lands with Sacramento and Amador Counties.

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.

North San Joaquin Water Conservation District (NSJWCD): 08/31/15: Received Resolution by NSJWCD requesting the assistance of GBA and its facilitator to submit a timely basin boundary modification request to DWR. Eastern San Joaquin Region Sustainable Groundwater Management Act Workgroup Public Meetings: 09/09/15: Agenda Item V ? Group discussion on Basin Boundary Revisions. 10/14/15: Agenda Item I.C. ? Group discussion on Proposed Basin Boundary Revisions. 02/10/16: Agenda Item: I.C. ? Group discussion on Basin Boundary Modification Update. Eastern San Joaquin County Groundwater Basin Authority (GBA) Public Meetings: 09/09/15: Agenda Item B.1. ? Action item approved by GBA Board to consider request by North San Joaquin Water Conservation District to request Basin Boundary Modification. 12/09/15: Agenda Item B.1 ? Action item approved by GBA Board to file with the DWR a Notice of Interest to Explore a Basin Boundary Modification. 01/13/16: Agenda Item A.1. ? Action item approved by GBA Board to direct staff to prepare a Basin Boundary Modification Request to DWR. 01/13/16: Agenda Item B.2 ? Communication/copy of ?Filing with the DWR a Notice of Interest to Explore a Basin Boundary Modification disseminated within GBA Board Agenda Packet.

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.

As of the date of this application submittal, no written comments have been received.

G. General Existing Groundwater Management

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

The proposed modification will enable the NSJWCD to efficiently manage the groundwater within the District with a single, focus effort instead of dividing the limited resources available to the District into to subbasins.

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

The proposed modification will not affect the efforts of the surrounding subbasins to sustainably manage their groundwater. The modification does not change the coordination effort between the adjoining subbasins required by SGMA.

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

Since 1971, the San Joaquin County Flood Control and Water Conservation District has monitored groundwater levels and groundwater quality which is published in semi-annually in a groundwater report. An evaluation was done on the data from the attached Fall 2012 Groundwater Report. The evaluation of several hydrographs indicates that groundwater elevations declined in many of the wells throughout the County from the beginning of the period of record (around 1958) through 1980. However, beginning around 1980, a number of wells demonstrated a slowing of water level declines or substantial recovery. Since 1980, only 3 of the 28 wells evaluated show consistent declines. the remainder are either stable or have increasing groundwater elevations. this is due to changes in land use, cropping patterns, irrigation practices, urban water efficiency improvements and a number of substantial investments to utilize more surface water. While portions of the basin continue to exhibit depressed groundwater levels due to past overdraft conditions, the actions described above have significantly addressed overdraft conditions.

Attachment(s):

• SJ-10_EasternSanJoaquinGWB_GWMP_2004.pdf (7.8MB) Uploaded on 03/18/2016 at 09:35AM
• Groundwater Report Fall 2012.pdf (7.5MB) Uploaded on 03/18/2016 at 04:12PM
• Groundwater Management Efforts.docx (24.9kB) Uploaded on 03/18/2016 at 03:57PM

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.

There will be no impacts to these programs. The existing groundwater management plans split the basin at the county line similar to the proposed boundary modification with separate plans developed north and south of the county line. San Joaquin County is the designated monitoring entity for the area of the Cosumnes Subbasin within the county. The area north of the county line is not CASGEM compliant. The proposed modification will not affect these designations.

H. Local Support

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

The consultations with affected agencies and listing of noticed public meetings are discussed above. In addition, the attached draft letter will be sent to the Interested Parties list within 5 days after DWR determines the application to be complete.

Attachment(s):

• Basin Boundary Notification Letter.docx (19.2kB) Uploaded on 03/17/2016 at 02:18PM

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.

As of the date of this application submittal, no comments have been received.

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

As of the date of this application submittal, no opposition had been received. However, 3 letters were uploaded to DWR during the public comment period. The comments made by the City of Galt, Trout Unlimited and Galt Irrigation District have been reviewed and a meeting was held with representatives of DWR, North San Joaquin Water Conservation District, San Joaquin County, the City of Galt, Galt Irrigation District, Clay Water District and the Southeast Sacramento County Agricultural Water Authority on May 20, 2016 to discuss the concerns and comments. A phone conference with the Trout Unlimited representative and North San Joaquin Water Conservation District was conducted on May 24, 2016. The result of the meetings and conversations was positive. Please see the attached file below for details of the response to the comment letters.

Attachment(s):

• NSJ response re comments on basin boundary mod.pdf (1.1MB) Uploaded on 05/26/2016 at 09:36AM

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.

BASIN HYDROGEOLOGY Geologic formations within the Central Valley and San Joaquin County are generally grouped as either east-side or west-side formations based on their location relative to the San Joaquin River, and the source of the sedimentary material of which they are composed. Generally, Eastside formation material originates in the Sierra Nevada and Westside formation material originates in the Coastal Ranges. The most important fresh water-bearing formations in Eastern San Joaquin County are the Mehrten, Laguna, Victor, and alluvial deposits. The formations are described below. Mehrten The Mehrten Formation is considered the oldest significant fresh water-bearing formation within Eastern San Joaquin County. It is exposed in the eastern most portion of the county, and slopes steeply from 90 to 180 feet per mile reaching a depth of 800 to 1000 feet and a thickness of 400 to 600 feet in the Stockton ands, and gravels, the formation is often subdivided into upper and lower units. The upper unit is reported to contain finer grained deposits (black sands interbedded with brown-to-blue clay) and the lower unit consists of dense tuff breccia (Page, 1986). Consequently, groundwater is reported to be semi-confined in the Stockton area. The Mehrten Formation has moderate to high permeability where black sands occur. (DWR, 1967, Brown & Caldwell, 1985) Laguna The Laguna Formation outcrops in the northeastern part of the County and dips at 90 feet per mile (DWR, 1967), and reaches a maximum thickness of 1,000 feet. It consists of discontinuous lenses of unconsolidated to semi-consolidated sand and silt with lesser amounts of clay and gravel. The Laguna Formation is moderately permeable with some reportedly highly permeable coarse-grained beds and generally unconfined, but semi-confined conditions probably exist locally. Some studies have suggested that an extensive aquitard, namely the Corcoran Clay, extends into the Laguna Formation or separates the Laguna and Mehrten Formations (Brown & Caldwell, 1985). Victor The Victor Formation is of Holocene to Pleistocene age and consists primarily of stream deposited unconsolidated gravel, sand, silt, and clay. Coarse sands and gravels are found to the east, and sands, silts and clays towards the west. This formation is generally more permeable than underlying formations, and groundwater is typically unconfined. (CDM, 2001) Alluvial/Stream channel deposits Stream channel deposits are found along major stream and river courses within the study area. Generally they consist of unconsolidated gravel and coarse sand with high permeability. GROUNDWATER FLOW DIRECTION Groundwater contours for the Eastern San Joaquin Basin show a groundwater cone of depression east of the City of Stockton. Regional groundwater flows converge from all directions toward this depression. Groundwater flow in the area to be added flows north from the Mokelumne River to a small depression near the Countyline. See attached Fall 2015 Groundwater Report for elevation contour maps and a north/south cross section. The requested jurisdiction internal subbasin boundary modification will allow for sustainable groundwater management of the subbasin in the manner that such groundwater management has occurred in the past. There are no new or changed hydrogeologic features resulting from this boundary modification. A detailed hydrogeologic conceptual model will be required with the future Groundwater Sustainability Plan. Therefore, it is requested that the requirement be waived.

Attachment(s):

• SJ-10_EasternSanJoaquinGWB_GWMP_2004.pdf (7.8MB) Uploaded on 03/18/2016 at 09:35AM
• Groundwater Report Fall 2015.pdf (3.4MB) Uploaded on 03/18/2016 at 03:59PM

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):

• SJ-10_EasternSanJoaquinGWB_GWMP_2004.pdf (7.8MB) Uploaded on 03/18/2016 at 09:35AM
• 1996 NSJWCD Groundwater Management Plan.pdf (1.1MB) Uploaded on 03/18/2016 at 09:36AM
• SSCAWA_GMP.pdf (35.5MB) Uploaded on 03/18/2016 at 09:37AM
• SOUTH_BASIN_GMP_FINAL_2011.pdf (12.3MB) Uploaded on 03/17/2016 at 04:46PM
• CMIRMP_Floodplain_Resources_Characterization_Report.pdf (30.1MB) Uploaded on 03/18/2016 at 09:38AM
• Eastern San Joaquin 2014 IRWMP Update 140605 rev21 (FINAL).pdf (58.6MB) Uploaded on 03/18/2016 at 09:46AM

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

The Eastern San Joaquin Subbasin agencies are in the process of organizing GSAs and discussing how to produce the required GSP. Noticed public meetings are currently held twice each month and will continue well into the foreseeable future. DWR representatives have been present at several of the meetings.