White Mountain Ranch Agricultural Well
Summary
SCH Number
2022050377
Public Agency
Mono County
Document Title
White Mountain Ranch Agricultural Well
Document Type
NOE - Notice of Exemption
Received
Posted
5/18/2022
Document Description
New 700' deep well for irrigation on an agricultural ranch in Hammil Valley, Mono County Ca. APN is 026-040-011. The permit is ministerial. See attached for more information about well location and seperation.
Contact Information
Name
April Sall
Agency Name
Mono County CDD
Job Title
Planning Analyst
Contact Types
Lead/Public Agency
Phone
Email
Name
Louis Molina
Agency Name
Mono County
Job Title
Environmental Health Director
Contact Types
Lead/Public Agency
Phone
Email
Location
Counties
Mono
Regions
Southern California
Parcel #
026-040-011
Other Location Info
Hammil Valley
Notice of Exemption
Exempt Status
Ministerial
Type, Section or Code
Sec. 21080(b)(1); 15268
Reasons for Exemption
Mapping resources indicate the property to the west (APN 026-040-088) has a well on the north end of the property which appears to be over 4000’ from the proposed well. According to Environmental Health records, the well on the property directly to the north (APN 026-040-009) is approximately 3000’ from the proposed well. Based on a review of the State Water Resources Control Board’s Low-Threat Underground Storage Tank Case Closure Policy, a 1,000-foot separation from active production wells to contamination plumes is considered to be sufficient separation to pose a low threat to human health, safety or the environment, and appropriate for no further action determination based on the groundwater-specific criteria specified. Further, this proposed well is within the key assumptions of modeling work by Santa Barbara County demonstrating that a new or replacement well located more than 1,000 feet from an existing well is not likely to interfere with the production of that well. The
modeling is based on hypothetical water well drawdown using conservative yet anticipated values for transmissivity, storage coefficient, and anticipated pumping yields to support field grown agriculture commodities.
According to the Owens Valley Groundwater Basin Final Groundwater Sustainability Plan of Dec. 9, 2021 (see Appendix A, p. 7): The hydrogeologic setting in the Fish Slough and Tri-Valley management area is dominated by volcanics and alluvial fan sediments which are typically not susceptible to subsidence. Groundwater levels in this area are showing chronic declines with rates observed to be about 0.15 feet/year (Fish Slough) and 0.49 – 1.86 feet/year (Tri-Valley) and are thought to be historic lows for this management area. The groundwater extractions in this management area are distributed throughout the area rather than being concentrated in small zones, so the effects of subsidence, if any, may be more area-wide. Despite one of the necessary factors being present, there is no direct instrumental evidence of subsidence in the management area. Consequently, the potential for subsidence is considered low.
County Clerk
Mono