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Contaminated groundwater in the Central Valley

Groundwater diagram picturing both the input and output of water.

Contaminated groundwater in the Central Valley is a growing problem in many of the agriculture-based communities based in the area. Combined with the overdraft of the underground aquifers, groundwater contamination is becoming increasingly worrisome as the amount of clean groundwater dwindles down. Near-term solutions to this growing problem are often costly and hard to implement in a timely manner while also clearing the water as safe to use. Currently nitrates are the most abundant of these pollutants in the Central Valley due to the copious amounts of agricultural runoff that comes from the numerous farms in the valley.

Background

The pumping of groundwater has been happening in the valley since 1850 when residents began to construct pumps to help make up for the lack of surface water in the area. From 1906 to 1920 alone, the number of wells jumped from 600 to nearly 11,000 and continued increasing dramatically with the invention of a deep-well turbine pump that allowed farmers to dig even deeper into the aquifer. The Central Valley contains an estimated 7 million of the state’s total 9 million acres² of cropland, many of which depend on groundwater to sustain its crops. Furthermore, over 80% of California’s dairies are located within the Central Valley with an estimated 1.8 million mature cows calling the area home. This makes these aquifers extremely important because groundwater supplies much of the water needed for agriculture to be grown and serves as the only source of water for several communities throughout the valley. However, there is not a reciprocal amount of water being used to recharge the aquifers and recent years have seen an increase in wells drying up. This overdraft of groundwater is causing numerous problems for farmers throughout the valley and is only made worse with the effects of climate change. The first bill that was passed regulating groundwater access, the Sustainable Groundwater Management Act, was the first of its kind to specify how to manage the groundwater in way that would not harm or endanger the future generation's access to clean, groundwater. Before this act, there was no regulations surrounding groundwater management other than the Safe Drinking Water Act and the Clean Water Act. Even these acts, however, do not totally protect Central Valley residents. For example, if aquifers are thought to already be contaminated, under the Safe Drinking Water Act, that aquifer can now accept wastewater from drilling projects because no residents should be receiving water from these wells. However, this results in low income communities potentially losing the majority of their water source

Pollution of Groundwater

File:Dairy2.jpg

Dairy cows eating. Central Valley contains about 80% of the state's dairies.

Nitrates are the leading pollutant of aquifers in the Central Valley. The nitrogen that leaches in the soil from fertilizers and the large number of dairies are the main causes of this abundance of nitrate in the area. However,other sources such as septic waste and natural sources have also been examined as possible sources of nitrate in groundwater.The source of pollution originates from a variety of these four sources (manure, fertilizers, septic waste, and natural sources) but it has been shown that the main source of nitrate is determined by proximity to the well. Areas with large amounts of dairies were shown to have high amounts of manure based nitrates whereas areas that applied fertilizer to their crops had an increased amount of fertilizer based nitrates entering the groundwater. Urban areas tended to have nitrate in the form of septic waste and natural sources of nitrate were found everywhere in small amounts .

Solutions

Efforts are on-going to treat polluted groundwater in way that is both efficient and effective. Through improved crop management, farmers are able to lessen the amount of fertilizer that is used on their crops and ultimately reduce the amount of nitrates entering their groundwater. Dairies are also now required to produce nutrient and waste management plans as well as report the manure tonnage and water quality of their well to help control the amounts of pollutants. The Central Valley Irrigated Lands Regulatory Program was originally created to monitor and regulate surface waters but has since expanded its scope to groundwater as well. The program regulates several tens of thousands of individual farms and oversee an estimated 7 million acres of irrigated lands and has required many districts to have now organized a Groundwater Assessment Report (GAR) to identify both historical and current trends in groundwater quality as well as to seek out areas that need improvement in terms of water quality. The GAR determines the different areas requirements and action plans because each area will have various levels of pollutants in their groundwater. The Sustainable Groundwater Management Act also allows the state to be more proactive when it comes to managing aquifers. The act gave some of the most stressed basins until the year 2020 to devise a plan to achieve groundwater sustainability over the next 20 years but the act still allows the State Water Board to step in if the basin is not meeting its target or requires help.