Groundwater Monitoring Shows Stable Conditions
Decades of agricultural measurements at Cadiz inform groundwater planning, while the Mojave Groundwater Bank’s management plan provides ongoing monitoring and enforceable safeguards.
Cadiz’s agricultural monitoring provides decades of water-level, water-quality, pumping and land-elevation data for planning the Mojave Groundwater Bank. A 2019–2023 report found no significant adverse impacts from agricultural pumping. That record supports project modeling and management, with continued monitoring, technical review and corrective action under the County-approved plan.
Summary
- Cadiz’s agricultural monitoring program grew from County requirements in the 1993 environmental review and a groundwater monitoring plan approved in 1997.
- The 2019–2023 agricultural report found groundwater levels within seasonal pumping and recovery ranges and no significant changes in groundwater quality.
- Agricultural elevation surveys in 2021–2023 found no evidence of subsidence relative to the 1997 baseline.
- The Mojave Groundwater Bank’s management plan builds on the agricultural record with pre-operational monitoring, technical review and enforceable corrective measures.
Decades of Measurements Support Groundwater Planning
Cadiz’s agricultural monitoring program tracks groundwater levels, water quality, pumping and land-surface elevations under County requirements established in the 1993 environmental review. The County approved the agricultural groundwater monitoring plan in 1997. The reporting history includes five-year summaries, a groundwater assessment accepted as the third report in 2012, and subsequent reports covering 2013–2018 and 2019–2023.
The Fifth Five-Year Monitoring Report, prepared by Geoscience Support Services, documents that history and the transition toward the project’s Groundwater Management, Monitoring and Mitigation Plan. It records submission of a draft implementation work plan to the Technical Review Panel in June 2024 and describes expansion of the agricultural monitoring network for project operations.
Historical measurements also provide a basis for groundwater modeling. The environmental review describes how modelers compared simulated water levels with measured well levels from 1986–1997, adjusting model parameters to match the historical record. This is a practical use of field data: testing whether a model reproduces observed conditions before using it to assess planned operations.
Groundwater Levels Remained Within Seasonal Ranges
Groundwater levels at Cadiz’s irrigation wells declined slightly as pumping increased, but variations remained within normal seasonal pumping and recovery ranges. Monitoring wells outside the wellfield’s pumping influence showed no significant long-term fluctuations, according to the 2019–2023 report.
Irrigated acreage increased from 795 to 1,145 acres over the reporting period. Annual production rose through 2022, reaching 8,068 acre-feet, then decreased to 6,134 acre-feet in 2023. The report describes the effect on static water levels immediately surrounding the wellfield at approximately 8,000 acre-feet annually as negligible.
The report also inferred no overall change in groundwater storage during the reporting period from the water-level records outside the wellfield, particularly in and north of the Fenner Gap. Its overall conclusion was that agricultural pumping had caused no significant changes or adverse impacts to groundwater levels, storage, quality or land-surface stability during 2019–2023.
Monitoring Found Stable Groundwater Quality
The 2019–2023 monitoring report found no significant changes in groundwater quality over the five-year reporting period. Total dissolved solids, a measure of dissolved material in water, were generally stable in the wells nearest the agricultural wellfield. Repeated sampling provides a record of water quality as agricultural operations continue.
Earlier hydrology and water-quality analysis provides regional context. The 2011 environmental review described groundwater in the Fenner Gap and Fenner Valley area as relatively good quality, with total dissolved solids typically ranging from 300 to 400 milligrams per liter. The historical regional findings and ongoing well sampling help characterize the freshwater supply and guide water management.
Elevation Surveys Found No Evidence of Subsidence
Land-surface surveys in 2021, 2022, and 2023 found elevations similar to earlier surveys, with no evidence of subsidence relative to the 1997 baseline. Subsidence means the lowering of the ground surface; comparing surveyed elevations over time helps identify whether that movement is occurring.
The 1997 survey established reference elevations at irrigation and monitoring wells. Later surveys extended the record, and additional control points expanded the subsidence network. These reference points allow land elevations to be compared over decades.
Agricultural Monitoring Carries Forward Into Project Safeguards
The County-approved management plan sets requirements for monitoring before, during and after project operations. It covers groundwater levels, water quality, springs, subsidence, vegetation and air quality, with corrective measures that include reducing or stopping pumping to protect resources.
Cadiz’s 2023 monitoring announcement describes more than 100 separate monitoring elements in the plan. Agricultural measurements contribute to the transition into that broader program, providing historical conditions against which subsequent measurements can be compared. The 2019–2023 report explains how the agricultural network would expand through additional production wells and survey points.
The 2019 peer review supported the management framework and recommended monitoring refinements. The separate Technical Review Panel reviews data and recommends responses. San Bernardino County retains final decision authority under the plan, and Santa Margarita Water District retains its own enforcement responsibilities.
The plan provides public access to annual reports upon written notification to the County and requires five-year reports to be available electronically.
A Long Monitoring Record Supports Groundwater Protection
Decades of agricultural measurements and data give the Mojave Groundwater Bank a foundation for groundwater modeling and management. The 2019–2023 report found seasonal water-level responses, generally stable water quality and no observed subsidence relative to the 1997 baseline. The County-approved management plan carries monitoring forward with technical review and enforceable corrective measures to protect groundwater and surrounding resources as the project develops.
Frequently Asked Questions
How Much Did Irrigated Acreage Increase During 2019–2023?
Irrigated acreage at the Cadiz agricultural development increased from 795 to 1,145 acres. The report associates the increase in groundwater production through 2022 with the expansion of farming acreage. Annual groundwater production for irrigation reached 8,068 acre-feet in 2022 and decreased to 6,134 acre-feet in 2023.
What Did Monitoring Find About Groundwater Quality?
The 2019–2023 report found no significant changes in groundwater quality over the reporting period. Total dissolved solids were generally stable in the wells nearest Cadiz’s agricultural wellfield. Repeated sampling provides information for managing the groundwater supply.
Did the Monitoring Report Find a Change in Overall Groundwater Storage?
The report inferred no overall storage change during 2019–2023 from monitoring-well records outside the wellfield. Those records showed no significant long-term water-level fluctuations, particularly in and north of the Fenner Gap.
How Does Agricultural Monitoring Support the Mojave Groundwater Bank?
Agricultural measurements provide historical water-level, water-quality, pumping and land-elevation data for groundwater modeling and project planning. The County-approved project plan builds on that record with pre-operational monitoring, technical review and enforceable corrective measures. The agricultural network would expand to support those project requirements.
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