To improve groundwater management we need to focus on more than the quantity our aquifers can supply. We also need to focus on quality.
Groundwater levels have been dropping in many of the state’s major aquifers, especially in parts of the Central Valley. This chronic issue was made worse by increased pumping during the latest drought. Lower water tables have resulted in increased pumping costs, the need for deeper wells, land subsidence, and salt-water intrusion into groundwater.
But groundwater supply is also harmed by pollutants, particularly nitrate and salt. Nitrate is widespread in many rural areas. Its major source is nitrogen fertilizer and manure. Salt, one of the most common pollutants, is in fertilizers, manure, and treated urban wastewater, and also occurs naturally. Both pollutants can compromise and ultimately reduce drinking water supplies. Salty groundwater is damaging to crops. In some areas, other contaminants such as naturally occurring arsenic also pose problems for drinking water.
Recently passed regulations seek to address both aquifer depletion and contamination issues with the goal of protecting groundwater resources for the long run. A suite of policies extended existing water quality protections to groundwater: the Central Valley Dairy Order, the Irrigated Lands Regulatory Program (ILRP), and the Central Valley Salinity Alternative for Long-Term Sustainability (CV-SALTS). More broadly, the Sustainable Groundwater Management Act (SGMA) directs agencies in charge of addressing groundwater depletion also avoid degrading water quality.
These regulations mark a historic shift in how groundwater is managed in California. They each provide distinct frameworks for addressing quality and quantity challenges. To reap the most benefits from their implementation, it will be important to coordinate management activities.
Under SGMA, more than 250 newly formed groundwater sustainability agencies will be in charge of managing groundwater resources. The jurisdiction and size of these agencies vary, and most groundwater basins have multiple groundwater sustainability agencies. The ILRP, which regulates runoff from irrigated lands, includes 12 coalitions statewide and thousands of farmers with individual waste discharge permits. The most effective solutions will require coordination and collaboration beyond the boundaries of these individual entities.
For instance, one way to address groundwater depletion is through intentional groundwater recharge. Because groundwater doesn’t respect property lines, recharge is best managed at a larger scale than most farms―ideally at the scale of an entire basin. Groundwater recharge can also affect water quality.
Depending on the soil type and crop choices, intentional recharge can improve or degrade the underlying water quality. Recharging in ways that benefit groundwater quality will entail coordinating cropping patterns, irrigation systems, and agronomic practices. The ILRP coalitions have already taken steps to assess areas that could be vulnerable to groundwater quality problems, promote farm practices that reduce pollution, and improve water quality monitoring. There are likely to be opportunities for GSAs to benefit from sharing resources on monitoring and planning with entities that manage water quality, such as ILRP coalitions. Forming partnerships in the early stages of drafting groundwater sustainability plans would be a good next step.
Coordinated management has the potential to address some tough, persistent water quality and quantity challenges, but it will generally take years before the benefits become apparent. Since groundwater depletion and quality degradation affect poor rural communities most acutely, more expeditious approaches are also needed. The state has been working on solutions to address the urgent public health issues these communities face. The SGMA also brings new opportunities to coordinate with local institutions to distribute and prioritize available resources.