Someone recently asked me about the Sustainable Groundwater Management Act (SGMA) and how it will affect our community. I didn’t have an immediate answer for that, since I am still learning about it. But it seemed like a good opportunity to dive into the world of groundwater management and review the history that has led us to the SGMA. I would still refer technical questions of sustainable groundwater management to the very knowledgeable folks over at the Carpinteria Valley Water District.
Groundwater is the water found below the Earth’s surface, stored in geologic formations called aquifers. This water comes from rainfall percolating into the ground. People have been relying upon groundwater for thousands of years for water supply, but in much smaller quantities. However, advances in technology allowed us greater access to groundwater in modern times.
Groundwater was still relatively underutilized as a resource until after World War II, when cheap energy and greater advances in pumping technology led to drawing water from aquifers at rates greater than it could be replenished or recharged. Also known as overdraft of the groundwater basin, our increasing reliance on groundwater led to unsustainable groundwater pumping in some areas, often due to a belief that groundwater was inexhaustible. Understanding the amount of groundwater available in a basin is important but not easy, since critical data is frequently unavailable.
When groundwater is pumped faster than it can recharge for many years, it can have negative impacts to other users, the environment and ecosystems. For example, the quality of the groundwater can degrade as the aquifer water stores are depleted and excessive depletion can even lead to land subsidence. In some areas, large expanses of wetlands have dried up as a result of overdraft. After many years of California’s groundwater resources being extracted without much oversight by the state, there was groundwater overdraft in many areas. SGMA was signed into law in 2014 to provide a mechanism whereby the state set certain minimum criteria for management of groundwater resources to be sustainable. Under this new law, the sustainable groundwater management activities for each groundwater basin was delegated to local agencies such as counties, cities and water districts.
It is important to note that while there are some basins in other areas of the state, these are considered critically overdrafted. The Carpinteria Groundwater Basin has been managed more carefully over the years and is not considered to be in overdraft.
Keeping groundwater sustainable is more than water conservation. While conservation is a critical part of long-term water management, diverting alternative water sources to infiltrate or be injected back into the groundwater basin can be an important tool for groundwater management. This does not mean diverting stream flows, which are important to maintain habitats, but instead taking advantage of underutilized resources such as storm flows, treated wastewater and even irrigation runoff.
Many urban environments were built with the goal of letting water pass through quickly (flood control) on its way to somewhere else. This disruption in the natural water cycle means that water that once was infiltrating into groundwater basins is now being swept to the nearest large body of water (in our case, the Pacific Ocean). Wastewater is another resource that is underutilized. Currently, we pump fresh water out of the ground and import water for potable use in the city, use it, send it to be treated and then discharge it to the ocean. If instead, we purify this “wastewater” to a safe level and store it in the groundwater basin for reuse, we improve the water quality condition of the groundwater basin as well as replenish the basin with water.
The SGMA will change the way local agencies manage groundwater resources for the next 50 years, requiring the agencies to improve their understanding of the groundwater basin, set goals for sustainability and prove to the state that the basin is managed sustainably.