B. Description of Proposed Boundary Modification

1. Short Description

   Establish the structurally controlled geologic contact and a portion of the Rinconada Fault system as the western Paso Robles Basin (No. 3-004.06) boundary in the area of the Nacimiento River.
2. Type of basin boundary revision

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

   This basin boundary modification request presents the scientific background and basis for proposing a basin boundary modification to exclude the upper Nacimiento River valley below the Nacimiento Dam (upper valley) from the Paso Robles Area Subbasin No. 3-004.06 (hereafter referred to as the Paso Robles Basin). The Paso Robles Basin has been assigned the following status by the California Department of Water Resources (DWR): High Priority Basin. SGMA revised the State Water Code to direct DWR to develop initial statewide groundwater basin priorities by January 31, 2015. It was determined that the initial statewide basin priorities would be equivalent to the prioritizations designated by California Statewide Groundwater Elevation Monitoring program (CASGEM) in June 2014. As a result of the CASGEM analysis the Paso Robles Basin is designated as high priority. Critical Overdraft - SGMA also directed DWR to identify groundwater basins and subbasins in conditions of critical overdraft. As defined by SGMA, A basin is subject to critical overdraft when continuation of present water management practices would probably result in significant adverse overdraft-related environmental, social, or economic impacts. As a result of this analysis, the Paso Robles Basin is determined to be in critical overdraft. In both of these cases, the decline in groundwater levels within the greater Paso Robles Basin overshadows the localized and distinctly different conditions of the upper Nacimiento River valley. The localized conditions in the upper valley do not share the high priority or critical overdraft status of the greater Paso Robles Basin. In fact, the localized conditions within the upper valley do not even involve percolating groundwater. The water in the upper valley shallow alluvium is legally considered surface water underflow, as there is essentially zero percolation of groundwater into the underlying bedrock. Considering the distinct geologic and hydrogeologic differences between the upper Nacimiento River valley and the greater Paso Robles Basin, it is our opinion that an external basin boundary modification to exclude the upper valley from the Paso Robles Basin is scientifically justified. The proposed basin boundary modification will have no effect on state programs, including but not limited to CASGEM, Groundwater Sustainability Plans developed pursuant to SGMA, any applicable state or regional board plans, or any other water management and land use programs. It will have no effect on, and will further promote, sustainable groundwater management of the Paso Robles Basin. Additional information and justification can be found in the technical report attached to this request.

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

   • 3-004.06 SALINAS VALLEY - PASO ROBLES AREA
5. Provide the proposed name for the new basin(s) or subbasin(s)

   Not applicable.

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)
   Templeton Community Services District	3-004.06 SALINAS VALLEY - PASO ROBLES AREA
   Heritage Ranch Community Service District	3-004.06 SALINAS VALLEY - PASO ROBLES AREA
   Monterey County Water Resources Agency	3-004.06 SALINAS VALLEY - PASO ROBLES AREA
   	3-004.05 SALINAS VALLEY - UPPER VALLEY AQUIFER , 3-004.06 SALINAS VALLEY - PASO ROBLES AREA
   	3-004.06 SALINAS VALLEY - PASO ROBLES 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):

• Att D1 Statutory Authority.pdf (3.6MB) Uploaded on 06/26/2018 at 09:27AM

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

Attachment(s):

• RESO 18-05 Initiating a basin boundary modification request 06222018.pdf (1.3MB) Uploaded on 06/26/2018 at 09:28AM

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):

• BBMR App D3.pdf (802.9kB) Uploaded on 06/26/2018 at 09:28AM

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

Attachment(s):

• D4 Proposed Paso Robles Subbasin modification.zip (55.3kB) Uploaded on 06/26/2018 at 09:29AM

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

Attachment(s):

• D5_Water_Districts_in_Paso_Robles_Subbasin_area.zip (410.4kB) Uploaded on 06/26/2018 at 09:29AM

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

The project is exempt from Section 21000 et seq. of the California Public Resources Code (CEQA), because it can be seen with certainty that there is no possibility that the project may have a significant effect on the environment (State CEQA Guidelines § 15061(b)(3)).

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 northern portion of the proposed basin boundary modification is delineated by a structurally controlled geologic contact which effectively separates the Paso Robles Basin aquifer materials east of the contact from the older, relatively impermeable geologic units to the west, including Tertiary-age consolidated sedimentary beds and Cretaceous-age metamorphic rocks; The southern portion of the proposed basin boundary modification is delineated by the Rinconada Fault system which forms an effective barrier to groundwater flow by juxtaposing Paso Robles Basin aquifer materials against the relatively impermeable units to the west; The maximum alluvial thickness in the upper Nacimiento River valley west of the geologic contact is 24 feet with a saturated thickness of approximately 17 feet. The alluvium is entirely underlain by bedrock (non-basin aquifer materials); See also Figures 4, 5, and 6 of the technical report attached to this request.

F. Notice and Consultation

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

By definition, there is one affected agency and zero affected systems. The affected agency is the San Luis Obispo County Flood Control and Water Conservation District/County of San Luis Obispo GSA because their jurisdictional area would be different (less area because it would be excluded). Attached is a list of all known local agencies and public water systems in the affected basin, with subsets of affected agencies and affected systems specifically identified.

Attachment(s):

• F1_Local agencies and PWS list.pdf (116.9kB) Uploaded on 06/26/2018 at 09:31AM

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

Local agencies and public water systems were identified by searching the State Water Board SDWIS website at, https://sdwis.waterboards.ca.gov/PDWW/index.jsp, and supplemented with known information from Heritage Ranch CSD and the County of San Luis Obispo. Announcements and/or discussion occurred at public meetings including several for the Paso Basin Cooperative Committee, the Water Resources Advisory Committee, and the Heritage Ranch CSD Board of Directors. The HRCSD website provides opportunity for interested parties to subscribe to an email list. The Paso Basin Cooperative Committee also established and maintains an outreach and education website tool as part of GSP development efforts. Correspondence was sent to identified agencies and/or public water system as indicated on the attached list. Attached is a list of all local agencies and public water systems in the affected basin with indication of mailed and emailed correspondence.

Attachment(s):

• F2_Local agencies and PWS correspondence list.pdf (116.9kB) Uploaded on 06/26/2018 at 09:32AM

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.

There is one affected agency as mentioned above. Consultation included mailed and emailed correspondence, public meetings, and meetings with staff, and/or telephone conversations. Additionally, although there is only one affected agency, correspondence was also sent to the other GSAs (interested local agencies) in the affected basin. Attached are the letters that were mailed and emailed as part of the consultation process, as well as responses received.

Attachment(s):

• F3_Consultations correspondence.pdf (15.6MB) Uploaded on 06/26/2018 at 09:33AM

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 summary of public meetings at which the current proposed boundary modification was discussed or considered by Heritage Ranch CSD is: • July 20, 2017, Board of Directors (Item 6b) • October 19, 2017, Board of Directors (Manager’s Report) • November 16, 2017, Board of Directors (Manager’s Report) • January 18, 2018, Board of Directors (Item 4a) • March 15, 2018, Board of Directors (Manager’s Report) • April 19, 2018, Board of Directors (Item 3b) • April 25, 2018, Paso Basin Cooperative Committee (Public Comment) • May 2, 2018, Water Resources Advisory Committee (Public Comment) • May 17, 2018, Board of Directors (Item 5a) • June 21, 2018, Public Hearing Notice • June 21, 2018, Board of Directors Public Hearing (Item 3a) Attached are copies of agendas, minutes, and notices for the listed public meetings.

Attachment(s):

• F4 Combined.pdf (14.1MB) Uploaded on 06/26/2018 at 09:49AM

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.

No comments have been received regarding the proposed boundary modification request (other than the support received as documented in our response to Item H2 below.)

H. Local Support

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

There is one affected agency, and zero affected systems as mentioned above. Information included mailed and emailed correspondence, public meeting discussion, and meetings with staff, as mentioned above. Additionally, although there is only one affected agency, correspondence was also sent to the other GSAs (interested local agencies) in the affected basin. Attached are the letters that were mailed / emailed as part of the consultation process, as well as responses received.

Attachment(s):

• H1_Evidence of Consultations reduced.pdf (2.4MB) Uploaded on 06/26/2018 at 09:54AM

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.

There is one affected agency, and zero affected systems as mentioned above. Although there is only one affected agency, correspondence was also sent to the other GSAs (interested local agencies) in the affected basin. A list of affected agencies/systems and interested local agencies that submitted comments and/or documents in support or opposition to the proposed boundary are: • San Luis Obispo County Flood Control & Water Conservation District/County of San Luis Obispo GSA • City of Paso Robles GSA • San Miguel Community Services District GSA • Shandon-San Juan Water District • Salinas Valley Basin GSA Attached are copies of the comments, resolutions, and/or signed letters detailing the support or opposition received.

Attachment(s):

• 2018_GSA_res_HRCSD.pdf (75.5kB) Uploaded on 06/26/2018 at 09:55AM
• Shandon-San Juan Water District - Heritage Ranch CSD GSA 118 basin boundary change support letter.pdf (68kB) Uploaded on 06/26/2018 at 09:55AM
• RE_ HRCSD BBMR_County.pdf (122.6kB) Uploaded on 06/26/2018 at 09:55AM
• RE_ HRCSD BBMR_City Paso.pdf (93.1kB) Uploaded on 06/26/2018 at 09:55AM
• RE_ HRCSD BBMR_SSJWD.pdf (93.8kB) Uploaded on 06/26/2018 at 09:55AM
• RE_ HRCSD BBMR_SMCSD.pdf (94.3kB) Uploaded on 06/26/2018 at 09:56AM
• Re_ HRCSD BBMR_SVBGSA.pdf (26.4kB) Uploaded on 06/26/2018 at 09:56AM

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

There has been no opposition received either implied or expressed; only support as provided above.

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.

The most significant geologic formation of the hydrogeologic conceptual model (HCM) of the upper Nacimiento River valley is alluvium. This unconsolidated collection of alluvial materials contains groundwater in the interstitial pore spaces between the sedimentary particles. It is defined laterally by contact with the Nacimiento Dam to the west, contact with the bedrock of the Santa Margarita, Monterey and Vaqueros Formations cropping out in the mountains on the north and south side of the valley, and the Paso Robles Basin to the east. It is defined vertically by the contact between the alluvium and the underlying bedrock. The maximum thickness of alluvium in the upper Nacimiento River valley is 24 feet. The primary source of inflow to the upper Nacimiento River valley alluvium is stream infiltration. The streamflow of the Nacimiento River is regulated through ongoing releases of surface water from the Nacimiento dam. This year-round streamflow infiltrates into and recharges the alluvium in the valley. Other sources of inflow include direct percolation of rainfall on the alluvium surface and mountain front recharge from runoff along the steep slopes on both sides of the valley. The primary outflow from the upper Nacimiento River valley alluvium is pumping of raw surface water from the Nacimiento River by HRCSD. Other outflows include evapotranspiration from the root zone of plants along the stream channel and surface water underflow out of the upper Nacimiento River valley into the Paso Robles Basin. The water level data from the upper Nacimiento River valley illustrate a long-term consistency of water level stability directly related to ongoing releases of surface water from the Lake Nacimiento dam. This indicates that inflows and outflows from the upper valley alluvium are in approximate equilibrium, and the alluvium has demonstrated sustainability over this time period. Additional information can be found in the technical report attached to this request.

J. Technical Studies for External Scientific Modifications

1. A qualified map that depicts the lateral boundaries of the aquifers that define the basin or subbasin.

Attached is a map that depicts the lateral boundaries of the basin in the area related to this request. Additional information can be found in the technical report attached to this request.

Attachment(s):

• BBMR App J1.pdf (968.3kB) Uploaded on 06/26/2018 at 09:58AM

2. A technical study that provides subsurface data that demonstrates the vertical thickness and relevant physical properties of the alluvial aquifer or stacked series of alluvial aquifers.

Attached is the Technical Report, Paso Robles Area Subbasin No. 3-004.06, Basin Boundary Modification Application, prepared for Heritage Ranch Community Services District, and dated May 2018. Also attached is a Technical Memorandum dated October 23, 2018, by GSI Water Solutions, Inc. Also attached is an Addendum dated December 17, 2018, by GSI Water Solutions, Inc.

URL: http://www.heritageranchcsd.com/Files/HR%20Basin%20Bndy%20Mod%20Tech%20Rpt_FINAL%20w%20Figures_BOD.pdf

Attachment(s):

• HR Basin Bndy Mod Tech Rpt_FINAL w Figures_BOD.pdf (4.9MB) Uploaded on 06/26/2018 at 10:01AM
• HR BBMR Addendum and Public Comments on Draft BBM 12172018.pdf (3.5MB) Uploaded on 12/17/2018 at 10:03AM
• HR BBMR Response to DWR Requests TM 181023.pdf (3.6MB) Uploaded on 10/24/2018 at 02:46PM