Chronic Lowering of GW Levels
Chronic Lowering of GW Levels
Chronic Lowering of GW Levels
Chronic Lowering of Groundwater Levels
- Click for Summary Analysis
The GSP established 17 RMPs throughout the Basin to track this sustainability indicator. The basin is not experiencing undesirable results under this indicator. Progress can be seen from 2016 to 2020 in that the number of RMPs achieving their MO increased from 1 to 3. However, one of those RMPs dropped back below its MO in 2024 after dry conditions were experienced in the Basin from 2020 through 2022. Conditions in WY2025 improved slightly with an additional well reaching its MO.
Seawater Intrusion
-
Click for Summary Analysis
The GSP identified protective groundwater elevations along the coast to help prevent further seawater intrusion (SWI). Elevations are currently monitored at 19 RMPs to track progress on meeting these criteria. The Basin is experiencing undesirable results due to 8 RMPs being below their MTs. However, progress can be seen since 2016 with the number of wells below their MT dropping from 12 to 8. Additionally, the number of wells achieving their MO has increased from 3 up to 6.
- Click for Summary Analysis
In addition to protective groundwater levels, the GSP also established maximum concentrations of chloride, which is typically an indicator of advancing seawater intrusion, in groundwater along the coast. These chloride criteria are measured at 36 RMPs along the coast, with data collected on a quarterly basis to track progress in meeting these criteria. The Basin is experiencing undesirable results due to 2 the RMPs being below their MTs. From 2016 to 2025, the number of RMPs achieving their MO has reduced and the number of RMPs below their MT has increased from 0 to 3. This issue is currently isolated to the Seascape area in the Basin and is under further investigation.
See the Projects and Management Actions page to find more information on what our Basin is doing to prevent and reverse the effects of seawater intrusion.
Reduction of Groundwater in Storage
Interconnected Surface Water Depletions
- Click for Summary Analysis
The GSP established protective shallow groundwater elevations near streams to prevent depletion of streams further than they existed prior to the passage of SGMA in 2014. Currently RMPs are established at 5 locations. The Basin is experiencing undesirable results due to 1 RMP being below its MT. However, progress can be seen from 2016 to 2020 with 1 RMP achieving its MO. There was no change in WY2025.
In 2022 and 2023, MGA constructed several new shallow monitoring wells in the Basin. As more data become available for these wells, groundwater elevation criteria will be established for these locations for additional RMPs.
Water Quality
- Click for Summary Analysis
The Water Year (WY) 2025 Water Quality Table shows sustainable management criteria (SMC) compared to WY 2025 maximum concentrations at representative monitoring points (RMPs) for the degraded groundwater quality indicator. SMC are met when concentrations are at or below criteria. Minimum thresholds (MTs) are based on drinking water standards for each constituent. Maximum concentrations at RMPs are also compared to measurable objectives (MOs) specific to each well based on average WY 2013-2017 concentrations. Where MOs are being met, the table is shaded green. Exceedances of MTs (red shading in the table) for chloride and total dissolved solids are related to seawater intrusion and addressed by that indicator.
In WY 2025, iron and manganese concentrations at several RMPs are greater than their respective MTs, but there were no significant changes from the previous year. These MT exceedances are not considered undesirable results because these were pre-existing naturally occurring conditions that have not changed from previous results.
Also in WY 2025, there was a nitrate exceedance at SC-A3C. In the October 2024 sample from SC-A3C, nitrate was reported at a concentration of 10.6 milligrams per liter (mg/L); the primary drinking water maximum contaminant level (MCL) is 10 mg/L. This is not an undesirable result because it was not caused by groundwater pumping or managed aquifer recharge. Previous nitrate MCL exceedances at SC-A3C occurred in 1997, 2000-2002, 2004-2009, 2011, and 2013. This shallow monitoring well is located in an unsewered residential area (La Selva Beach) where legacy nitrate issues were described in the GSP.
There were no detections of organic compounds in any active municipal extraction wells in the Basin.
Tracking SGMA Sustainability Indicators
For each RMP, the MGA is required to develop a minimum threshold (MT) and a measurable objective (MO). The MT is established such that, if not met, could indicate the Basin is experiencing undesirable results. The MO, on the other hand, represents an ideal level for each specific indicator at which the Basin could have prolonged drought conditions and still maintain sustainability. Under SGMA, the MGA has to meet MTs to avoid undesirable results, but there is no legal requirement to achieve the MO targets. In other words, the State defines a sustainable Basin as one without undesirable results.
This Sustainability Dashboard tracks each sustainability indicator with respect to both the MTs (achieving compliance with the law) and the MOs (achieving ideal sustainability). Each indicator is color coded as shown here.
While all RMPs are not required to be green to be in compliance with SGMA, this is the aspirational goal to provide the highest level of ensuring long-term sustainable groundwater in the Basin.
-
One or more measured values for an indicator are not meeting an MT.
-
The Basin is not currently experiencing undesirable results, but one or more MOs are not being achieved.
-
All MOs are met for a sustainability indicator.