Ukiah Valley Groundwater Sustainability Plan

The Sustainable Groundwater Management Act (SGMA), passed by the California legislature in
2014, requires local entities to jointly assess groundwater conditions in their local areas and to
develop a Groundwater Sustainability Plan (GSP) by a specified deadline to ensure that sustainable
conditions are achieved within 20 years of GSP adoption. An effective and efficient groundwater
management plan is critical for the local economy and the health and welfare of the people, the
environment, and all other beneficial uses and users of groundwater in a local area.

The Ukiah Valley Basin (Basin) is a medium-priority groundwater basin located in Mendocino
County. The sole Groundwater Sustainability Agency for the Basin is the Ukiah Valley Groundwater
Sustainability Agency (UVBGSA or GSA). The GSA consists of the following local agencies:
the County of Mendocino (County), the City of Ukiah (City), the Upper Russian River Water Agency
(URRWA), and the Russian River Flood Control and Water Conservation and Improvement District
(RRFC). The GSA applied for and was awarded Proposition 1 and Proposition 68 grant funds to
develop the GSP and meet the SGMA-mandated schedule for submitting a GSA-approved GSP
to the California Department of Water Resources (DWR) by January 31, 2022. GSA will be funded
through member agency contributions during the first 5-year implementation period until a fee
structure is implemented to support and fund GSA activities. Additional funding opportunities will
continue to be explored, including grants. In late-2022, DWR will open round 2 solicitations under
the SGMA Grant Program, which will provide approximately $204 million to high and medium
priority subbasins to implement the GSP and its projects and management actions.

A variety of local interests are represented by the GSA and served on the technical advisory committee
(TAC), including municipal-residential water users, agricultural water users, public water
systems, local land use planning agencies, environmental users, surface water users, tribal governments,
disadvantaged communities, groundwater monitoring and reporting entities, holders of
overlying groundwater rights, adjacent Basins, industrial users, commercial users, remediation
pumpers, natural ecosystems, and the general public. Many of these local entities have a long
history with groundwater and surface water management in the Basin and are well equipped to
perform SGMA-required planning functions.

The GSA, TAC members, and the public have undertaken a thorough and timely review of past,
current, and projected future water resources needs and groundwater conditions to meet SGMA
requirements for GSP development. Throughout the development of the GSP, regular communication
and engagement activities were conducted to inform and receive input from local stakeholders
and the public. The GSP includes a comprehensive groundwater basin description, which was
used to develop a regional integrated hydrological model that quantifies current water budgets and
projects future conditions of the Basin. The GSP also includes an assessment of the impacts of
predicted future groundwater levels on beneficial users, including groundwater-dependent ecosystems,
shallow wells, and interconnected surface water using the best available data and science
available. Importantly, these assessments are used to develop measurable sustainable management
criteria that avoid significant and unreasonable impacts to these beneficial users, and that
can be monitored and adjusted throughout plan implementation.

The key finding of the GSP, based on a thorough analysis of the best available information, is
that the Basin will be sustainable over the next twenty years if planned projects and management
actions (PMAs) are implemented as needed with respect to climate change and changes in the
water system.

These PMAs will help maintain groundwater levels and storage volumes and protect ecosystems,
interconnected surface water, and shallow wells. Potential climate change impacts are not fully understood at this stage due to data gaps and the need for additional modeling and data collection.
The GSP will implement a more comprehensive data collection that improves modeling capabilities
and can provide a better assessment of climate change impacts in the future. The proposed PMAs
will promote adaptive management practices and long-term resiliency to varying climatic conditions,
such as more frequent, longer-lasting, and more intense droughts and less frequent and
wetter winters. As described in Chapter 2, the sustainable yield for the entire Basin is estimated to
be at least 6,500 acre-feet, based on historical, average groundwater pumping. The sustainable
yield of the Basin is defined based on avoidance of undesirable results. Because the Basin is not
overdrafted and the historical pumping average may not represent the actual sustainability yield of
the Basin.

A groundwater monitoring network comprised of selected wells will be used to track groundwater
levels and groundwater quality. Sustainable management criteria set at representative monitoring
wells in the network will be implemented to gage these conditions over time and ensure that groundwater
levels and quality remain within a range that avoids significant and unreasonable impacts
to beneficial uses and users of groundwater. Streamflow measurements are added to the monitoring
network to measure surface water depletion due to groundwater pumping in combination
with groundwater level measurements and integrated hydrological modeling simulations. Monitoring
and data collection efforts will continue through the first five years of GSP implementation to
further identify and prioritize project and management actions.

Once approved by the GSA, the activities identified throughout the GSP development process will
be implemented, including:

• Ongoing monitoring and annual reporting on conditions in the Basin;
• Ongoing public engagement and outreach;
• Coordination within the watershed and with neighboring basins and water management entities;
• Development and implementation of a shallow well protection and monitoring program;
• Coordination with land use agencies and water supply agencies to promote consistency with
the GSP;
• Coordination with regional agencies in the development of updated climate change projections;
• Implementing PMAs as deemed needed by the GSA to maintain and promote sustainability
of the Basin; and,
• Preparation of five-year updates to the GSP starting in 2027.

Due to file size, the GSP is divided into separate files.

Part 1, Part 2, Part 3, Part 4, Part 5, Part 6