In Part 2 of this series, we covered the Basin Setting information and how to utilize that data. In this part, we look more closely at the quantitative data that determines whether or not a GSA is effectively managing their service territory towards sustainability.
Sustainable Management Criteria
The sustainable management criteria section of the GSP is designed to utilize the data provided in the previous sections to characterize what the undesirable results are for the basin, measures used to ensure basin operates within its sustainable yield, and an how the GSA plans to reach the sustainability goal in 20 years.
Sustainability Goals and Sustainability Indicators
Sustainability goals are tied to sustainability indicators. There are six sustainability indicators that become undesirable results if there are significant and unreasonable impacts to the sustainability indicator.
- Chronic lowering of groundwater levels indicating a significant unreasonable depletion of supply if continued over the planning implementation horizon.
- Significant and unreasonable reduction of groundwater storage
- Significant and unreasonable seawater intrusion
- Significant and unreasonable degraded water quality, including the migration of contaminant plumes that impair water supplies
- Significant and unreasonable land subsidence that substantially interferes with surface land uses
- Depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water
These indicators are specific to a point, but it is up to the GSP to further define how to measure and determine the significance and unreasonableness. The quantitative indicators will inform important decisions impacting agriculture like groundwater pumping restrictions and pesticide usage. Also of interest, are the milestones that are measured in increments of 5, 10, 15, and 20 years allowing for a baseline to make adjustments to GSA pumping restrictions and other regulations.
Minimum Thresholds and Metrics
|Sustainability Indicators||Metrics Required by SGMA*|
|Lowered Groundwater Levels||Groundwater Elevation|
|Reduction of Storage||Total Volume|
|Seawater Intrusion||Chloride Concentration Isocontour|
|Degraded Water Quality||Migrations of Plumes, Number of Supply
Wells, Volume, Location of Isocontour
|Land Subsidence||Rate and Extent of Land Subsidence|
|Surface Water Depletion||Volume or Rate of Surface Water
*Groundwater may be used as a proxy as discussed late in this article
Important metrics to review include: hydrographs, subsidence areas, and supply well information. Wells will typically be chosen to monitor for a broader area and are representative of that area. What is one of the more interesting measurements to note is groundwater elevation.
Groundwater elevation may be used as a proxy for any of the minimum thresholds for the sustainability indicators if the GSP demonstrates a correlation between groundwater levels and any of the other metrics.See 23 CCR §§ 354.30(d), 354.36(b)
In addition to the minimum thresholds for the GSA, the GSP requires observance of adjacent GSAs’ minimum thresholds due to the natural movement of water, and potentially contaminants, from one GSA service area to another. Understanding where your organizations portfolio or client’s land is in relation to neighboring GSAs can assist in better understanding whether a neighboring GSA’s GSP create a negative impact.
AQUAOSO tracks groundwater elevation in our research tool to assist in understanding the health of a groundwater basin and the specific parcel overlying that basin.
An “undesirable result” occurs when there is a significant and unreasonable condition measured by any of the six sustainability indicators explained in the above section. However, one exceedance at one monitoring well is not sufficient to be an undesirable result. Also, undesirable results may differ depending on management area or region of a GSA. It is important to identify where exactly in the GSA a portfolio or single property is located to understand the criteria for undesirable results.
Remember, remedying the undesirable result is a marathon, not a race. GSAs have 20 years to correct the undesirable result. While there are annual reporting requirements and milestones every 5 years, there is an expectation SGMA regulations that this process will take some time. Keeping an eye on changes to the GSP and the annual reports will provide an understanding of the general direction of the GSA and how likely an increase or decrease in groundwater pumping regulation will impact your organization.
The following are key takeaways for understanding GSP Sustainable Management Criteria and Metrics:
- There are 6 indicators for determining whether a basin has reached sustainability
- There are various metrics to measure the 6 indicators, of which groundwater levels may be used as a proxy as long as it is correlated with measurement of the indicator.
- Exceedance of an indicator creates an undesirable result.
- Undesirable results must be corrected at the end of the 20 year period that the GSP covers.
- Understanding how the metrics and indicators impact your organization is critical.
The GSPs are the tip of the groundwater data iceberg as more public information is available on level, quality, and availability of groundwater. Keeping track of the data is not an easy task. Making sense of it and applying that to actionable steps for your organization is an even more challenging task. At AQUAOSO Technologies, we work on these hard problems every day so you don’t have to.
Join us in building a water resilient future through advanced technologies today!