B. Description of Proposed Boundary Modification

1. Short Description

   EMWD requests a basin boundary modification of the DWR Bulletin 118 Subbasin No. 8-002.08, the San Timoteo Groundwater Subbasin (Basin), based on scientific (external) justification to better represent the local groundwater aquifer conditions.
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.

   The modification request is to eliminate areas of the existing Basin that lack viability and/or contribution to the local groundwater aquifer system. This boundary modification addresses areas of permeable materials capable of providing significant quantities of groundwater to wells and areas comprised of well-consolidated, Tertiary bedrock that should be excluded from the groundwater basin based on DWR's definition of a Quaternary groundwater basin. The proposed Basin boundary will coincide with the surface extent of unconsolidated young alluvium, old alluvium, alluvial fan, valley fill deposits, and other geologic formations having well understood and documented groundwater significance as mapped by the California Geological Survey (CGS). The proposed modification will not impact the sustainable management of the Basin because the areas identified for removal do not provide a significant source of water nor significant volumes of groundwater and there is no current or planned use for these areas that would constitute a significant contribution to water resources (Attachment B1). The Basin is the source of water supply for multiple purveyors (Attachment B2). The main production area is the adjudicated portion of the Basin identified by DWR in the basin prioritization released in 2018. The Beaumont Basin Watermaster actively manages the adjudicated portion of the Basin. The northeastern portion of the Basin (unadjudicated area) was previously managed under the San Timoteo Watershed Management Program implemented in 2005 prior to the passing of SGMA in 2014. This portion of the Basin is currently managed by the San Timoteo GSA and was classified as a very low priority basin (DWR, 2018).

   Attachment(s):

   Attachment B1 - Existing_San_Timoteo_Basin_Geologic_Map.pdf (2.5MB) Uploaded on 06/27/2018 at 10:24AM

   Attachment B2 - Existing_&_Proposed_San_Timoteo_Basin_Stakeholders_&_Land_Use_Map.pdf (5.3MB) Uploaded on 07/13/2018 at 09:08AM
4. List the existing basin(s)/subbasin(s) to be modified by this request

   • 8-002.08 UPPER SANTA ANA VALLEY - SAN TIMOTEO
5. Provide the proposed name for the new basin(s) or subbasin(s)

   There are no new proposed basins. After proposed boundary revisions, a single Subbasin name 8-002.08 San Timoteo will remain.

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)
   Yucaipa Valley Water District	8-002.08 UPPER SANTA ANA VALLEY - SAN TIMOTEO
   Beaumont-Cherry Valley Water District	8-002.08 UPPER SANTA ANA VALLEY - SAN TIMOTEO
   Eastern Municipal Water District	8-002.08 UPPER SANTA ANA VALLEY - SAN TIMOTEO

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):

• Attachment D1 - Certification of EMWD.pdf (223kB) Uploaded on 06/27/2018 at 10:30AM
• Attachment D2 - Southwest San Timoteo GSA Formation Submittal.pdf (2.8MB) Uploaded on 06/27/2018 at 10:34AM

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

Attachment(s):

• Attachment D3 - Resolution 2018-083.pdf (328.1kB) Uploaded on 06/27/2018 at 10:31AM

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):

• Attachment D4 - Existing_&_Proposed_San_Timoteo_Basin_Stakeholders_&_Land_Use_Map.pdf (5.3MB) Uploaded on 07/13/2018 at 09:10AM

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

Attachment(s):

• Attachment D5 - EMWD_Proposed_New_San_Timoteo_Basin_Boundary_Shapefile_20181015.zip (321.6kB) Uploaded on 10/15/2018 at 09:46AM

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

Attachment(s):

• Attachment D6 - EMWD_Entities_San_Timoteo_Shapefile.zip (165.7kB) Uploaded on 06/29/2018 at 06:57AM

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

This request is not a project as defined in the California Environmental Quality Act Code of Regulations, Title 14, Chapter 3, Section 15378.

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 Basin underlies Cherry Valley and the City of Beaumont in southwestern San Bernardino and northwestern Riverside Counties. It is bounded to the north and northeast by the Banning fault and impermeable rocks of the San Bernardino Mountains, Crafton Hills, and Yucaipa Hills, on the south by the San Jacinto fault, on the west by the San Jacinto Mountains, and on the east by a topographic drainage divide with the Colorado River Hydrologic Region. The surface is drained by Little San Gorgonio Creek and San Timoteo Canyon to the Santa Ana River. Holocene age alluvium, which consists of unconsolidated clay, silt, sand, and gravel, is the principal water-bearing unit in this Basin. The alluvium, which is probably thickest near the City of Beaumont, thins toward the southwest and is not present in the central part of the Basin (DWR, 2003). The San Timoteo Formation, located in the southwest portion of the Basin, consists primarily of well-consolidated, Tertiary sandstone and conglomerate. The geologic description of the San Timoteo formation is as follows: Dominant lithology is light-gray, pebbly to cobbly, moderately to well-indurated, medium- to coarse-grained sandstone containing conglomerate beds up to 9 meters in thickness. Pale brown- to light-gray fine-grained sandstone; pebbly sandstone is subordinate. Overall, member consists of about 70 percent sandstone and 30 percent conglomerate; conglomerate more abundant in upper part. Includes numerous reddish-brown stratigraphic intervals consisting of oxidized sandstone, which are not paleosols, and reddish brown clay-rich intervals, which may be paleosols. Erodes to form sharp-ridged badlands topography. In eastern part of quadrangle, forms hogbacks on south side of San Timoteo Canyon. Included within the San Timoteo Formation (Tstm) is highly deformed, fault-bounded sandstone, pebbly sandstone, and conglomerate (Tstd) located along western part of badlands adjacent to Claremont Fault (Morton, 1999).

Attachment(s):

• Attachment E1 - 8-2.08.pdf (33.1kB) Uploaded on 06/27/2018 at 01:52PM

F. Notice and Consultation

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

San Gorgonio Pass Water Agency Yucaipa Valley Water District Beaumont-Cherry Valley Water District South Mesa Water Company Banning Water District City of Redlands Water City of Beaumont Water Beaumont Basin Watermaster City of Calimesa City of Beaumont City of Banning City of Redlands

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

On May 14, 2018, the San Timoteo Sustainable Groundwater Management Agency held a meeting at San Gorgonio Pass Water Agency during which the basin boundary modification for the San Timoteo Groundwater Basin was discussed. On May 23, 2018, EMWD discussed technical comments with the members of the San Timoteo GSA for the San Timoteo Groundwater Basin boundary modification.

Attachment(s):

• Attachment F1 - 180514 San Timoteo GSA Agenda.pdf (10.1kB) Uploaded on 06/27/2018 at 03:07PM

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.

EMWD informed the San Timoteo GSA of the San Timoteo Groundwater Basin boundary modification request (southwestern portion of the Basin). Several technical discussions were held to resolve comments regarding the boundary modification. A consultation was held with the California Department of Water Resources, Southern Section on May 29, 2018.

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.

The San Timoteo Groundwater Basin boundary modification was discussed at the EMWD's Board of Directors meeting on June 20, 2018.

Attachment(s):

• Attachment F2 - 2018 06-20 Board Agenda.pdf (466.6kB) Uploaded on 06/27/2018 at 03:08PM
• Attachment F3 - Resolution 2018-083.pdf (328.1kB) Uploaded on 06/28/2018 at 03:49PM

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 were received apart from the comments discussed during the technical meetings with members of the San Timoteo GSA.

H. Local Support

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

On May 14, 2018, the San Timoteo Sustainable Groundwater Management Agency held a meeting at San Gorgonio Pass Water Agency during which the basin boundary modification for the San Timoteo Groundwater Basin was discussed. On May 23, 2018, EMWD discussed technical issues with the members of the San Timoteo GSA for the San Timoteo Groundwater Basin boundary modification request.

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.

EMWD's Board of Directors adopted a Resolution (2018-083) initiating the San Timoteo Groundwater Basin boundary modification.

Attachment(s):

• Attachment H1 - Resolution 2018-083.pdf (328.1kB) Uploaded on 06/29/2018 at 06:59AM

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

None submitted.

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 San Timoteo Formation is composed primarily of sandstone, conglomerate, siltstone, and mudstone (Rewis, et al., 2007). The igneous and metamorphic rocks form the crystalline basement rocks in the area (Bloyd, 1971). The unconsolidated Quaternary alluvium, and the upper portion of the underlying San Timoteo Formation, constitutes the water-bearing aquifer of the Beaumont Basin (Rewis, et al., 2007). The San Timoteo barrier separates the lower San Timoteo Canyon area from the main part of the San Timoteo-Beaumont basin (USGS, 1972). There are three significant drainage systems that overlie the Beaumont Basin: the San Timoteo Creek drainage which is tributary to the Santa Ana River; the Potrero Creek drainage system in the San Jacinto watershed; and the Smith Creek drainage system tributary to the White Water River which is part of the Salton Sea drainage basin. Surface water flows originate in the San Bernardino Mountains to the north of the Basin (ALDA, 2013). Attachment I1 - Ground-Water Outflow, San Timoteo-Smiley Heights Area Upper Santa Ana Valley, Southern California 1927 through 1968. February 9, 1972. Attachment I2 - DWR Bulletin 118 Upper Santa Ana Valley Groundwater Basin, San Timoteo Subbain Attachment I3 - Existing San Timoteo Subbasin Geologic Map Attachment I4 - Engineer's Report No. 3 2008-2011 Attachment I5 - Second Report Of Recharge Parties Pursuant To RWQCB Resolution No. R8-2008-0019 Cooperative Agreement To Protect Water Quality And Encourage The Conjunctive Uses Of Imported Water In The Santa Ana River Basin, Yucaipa And San Timoteo Management Zones

Attachment(s):

• Attachment I1 - Ground-Water Outflow.pdf (643.1kB) Uploaded on 06/27/2018 at 03:55PM
• Attachment I2 - 8-2.08.pdf (33.1kB) Uploaded on 06/29/2018 at 10:55AM
• Attachment I3 - Figure_3_-_Existing_San_Timoteo_Basin_Geologic_Map.pdf (2.5MB) Uploaded on 06/29/2018 at 10:55AM
• Attachment I4 - Engineer's Report No. 3 2008-2011.pdf (8.5MB) Uploaded on 06/29/2018 at 10:55AM
• Attachment I5 - 120718_FINAL-Rech-Coop-Agrmnt_Yucaipa_SanTimoteo.pdf (18.2MB) Uploaded on 06/29/2018 at 10:55AM

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.

Attachment J1 - San Timoteo Basin 8-002.08 Geologic Map Attachment J2 - Proposed New San Timoteo Basin 8-002.08 Boundary Geologic Map

Attachment(s):

• Attachment J1 - Figure_3_-_Existing_San_Timoteo_Basin_Geologic_Map.pdf (2.5MB) Uploaded on 06/28/2018 at 02:13PM
• Attachment J2 - Figure_4_-_Proposed_San_Timoteo_Basin_Geologic_Map.pdf (2MB) Uploaded on 07/13/2018 at 09:15AM

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.

The hydrogeology of the Basin was analyzed by reviewing data presented in the technical documents listed below and included in Section I. Justification for the modification is presented in Attachments J3 and J4. Attachment J3 - San Timoteo Groundwater Basin Boundary Modification Justification Attachment J4 - San Timoteo Groundwater Basin Boundary Modification Justification Maps Attachment J5 - Conceptual Understanding and Groundwater Quality of Selected Basin-Fill Aquifers Attachment J6 - 2013 Reevaluation of the Beaumont Basin Safe Yield

Attachment(s):

• Attachment J6 - 2013 Reevaluation of the Beaumont Basin Safe Yield.pdf (16.6MB) Uploaded on 06/29/2018 at 11:19AM
• Attachment J5 -Conceptual Understanding and Groundwater Quality of Selected Basin-Fill Aquifers.pdf (8.1MB) Uploaded on 06/29/2018 at 11:19AM
• Attachment J4 - San Timoteo Groundwater Basin Boundary Modification Justification Maps.pdf (29.3MB) Uploaded on 07/13/2018 at 09:16AM
• Attachment J3 - SanTimoteo Groundwater Basin Boundary Modification Justification.pdf (132.8kB) Uploaded on 06/29/2018 at 11:04AM