Central Valley groundwater pollution

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Aerial view of Central Valley waterways. California Central Valley Aerial.jpg
Aerial view of Central Valley waterways.

Contaminated groundwater in the Central Valley of California is a growing problem due to contamination and overuse. [1] This problem is compounded by the overdrafting of underground aquifers. [1]

Contents

nitrates are the most abundant pollutants in the Central Valley due to the copious amounts of agricultural runoff from the farms. [2] The concentration of naturally occurring arsenic is also an issue. [3] This is a public health concern as groundwater is often the primary water source in the region. [1]

Near-term solutions to reduce pollution and overuse are often costly and hard to implement in a timely manner.[ citation needed ]

Background

At the heart of this industry lies the Central Valley, a vital agricultural hub for the state and country. Consisting of both the San Joaquin Valley and Sacramento Valley, the Central Valley has an estimated two-thirds of the state's cropland with 7 million acres. [4] California is also the leading dairy producer in the country, with 1.8 million mature cows in the Central Valley contributing to 80% of California's dairies. [5] [6] Water quantity and quality have been a leading concern in this crucial high-output agricultural region that often suffers from drought.

History

Map of the Central Valley region of California. Map of the Central Valley region of California.png
Map of the Central Valley region of California.

Groundwater has been pumped in the valley since 1850, when residents began to build pumps to help make up for the lack of surface water in the area. [2] At the turn of the 20th century, California became as a leading agricultural producer due to its technological advances in land management, irrigation and machinery. The Central Valley had ideal economic and climate conditions for many crops and drew in wealthy landowners.

Aquifers are critical because groundwater supplies much of the water needed for agricultural purposes and serves as the only source of water for several communities throughout the valley. [7] However, reciprocal rainfall is not always available to recharge the aquifers, and recent years have seen an increase in drying wells. This overdraft of groundwater causes numerous problems for farmers and is only made worse by climate change. [2] Throughout the early 1900s, technology for waste management did not advance at the same speed as the growth in agriculture. [8] Issues in groundwater contamination by nitrates come from 50 years of unregulated management of livestock waste disposal, septic systems and commercial fertilizers. The California Sustainable Groundwater Management Act of 2014 was the first to specify how to manage groundwater in a way that would not harm or endanger future access to clean groundwater. [2]

Before this act, no regulations governed groundwater management other than the federal Safe Drinking Water Act and Clean Water Act. These acts do not totally protect Central Valley residents. Consistent monitoring didn't begin until the 1950s, with only 13,000 tests completed in the 1980s compared to the over 133,329 tests in the Central Valley region conducted by the California Spatio Temporal Information on Nitrate in Groundwater (CASTING) database. [9] With advances in testing and research, organizations and residents of the Central Valley have increased efforts to reduce the impact of nitrate water pollution, expected to drastically increase in the next couple decades. [10]

Regulations and standards

Set by the California Department of Public Health,[ when? ] the maximum contaminant level for nitrates, in CCR §63341, is 45 milligrams per liter (mg/L) for nitrate as NO3 (equivalent to 10 mg/L for nitrate as nitrogen or “N”); 10 mg/L for nitrate plus nitrite as N; and 1 mg/L for nitrite as N. Public wells are required to test their water annually and submit the results to the Department of Health, but private wells are not required to do so. A documented 98% of the state has access to drinkable water, though some studies note that access disparities exist. [11]

Despite modern data and methods for agricultural safety, 92 water systems in the Central Valley were attached to wells containing illegal levels of nitrates between 2005 and 2008, impacting the 1,335,000 residents in the area. [11] Historically, programs to identify and address the impact nitrates have on communities and industries have run at around $1 million each. [12]

The Californian Sustainable Groundwater Management Act of 2014 was the first of its kind to specify how to manage groundwater in a way that would not harm or endanger future generations' access to clean groundwater. [1] Signed by Gov. Jerry Brown in 2014, this three-bill legislative package created a framework for preserving and managing groundwater at the local and state level. This creates a regulatory process mandating that Groundwater Sustainability Agencies (GSAs) to adopt Ground Water Sustainability Plans (GSPs) to manage supply. Before this act, regulations existed only at the federal level with the Safe Drinking Water Act and the Clean Water Act, which failed to protect Central Valley residents. Based on these laws, farms and oil drilling sites could not dump waste into the ground if it impacted clean drinking water;[ citation needed ] however, if the water was not suitable to drink, consumers and businesses could dump waste freely into the water, limiting access to drinking water by further contaminating sources already deemed undrinkable. [9]

Sources of nitrogen

Manure, fertilizer, and septic waste are the leading sources of nitrates in groundwater. Manure produces around 6.5 million tons of nitrogen, which, when not handled properly or with improper drainage methods, can contaminate soil and water sources.[ citation needed ] Nitrogen-based soil compounds produced by crops such as legumes, are consistently a minimal source. [13] Fertilizers add roughly 11.5 million tons of nitrogen annually in the United States. Nitrogen in fertilizers is converted to nitrates, which is the main form of nitrogen in wastewater. Nitrogen from fertilizers can also be released into the atmosphere as ammonia gas, commonly recognized as a greenhouse gas. In the U.S. 53% of nitrates originate from fertilizers, making this a priority for Californian officials.[ citation needed ]

Population impact

Several studies have investigated the impact of nitrogen-based wastes such as nitrates on human health. Some studies suggest that exposure to such wastes is correlated to an increased risk of cancer. The exposure period is a determining factor in increased risk consistent through all of the studies.[ citation needed ] In cases where the incidence of cancer was found to be significantly higher, the exposure period was at least five years, and in some cases up to ten years.

Women who consume water with nitrates over 5 mg/L are at a higher risk of thyroid cancer. [14] This 5 mg/L level is 5 mg below the federally accepted limit. When consumed, nitrate competes with iodine in the body to be taken up by the thyroid. When the thyroid intakes nitrogen instead of iodine, it begins to lose function.[ citation needed ] Only five years of this exposure significantly increases the risk of thyroid cancer. A higher risk of colon and rectal cancer also accompanies water consumption with nitrate levels above 5 mg/L. Exposure for 10+ years is associated with increased colon cancer risk in susceptible populations. [15] Populations affected may also lack access to fresh fruits and vegetables, and a lack of vitamin C is a major risk factor for colorectal cancers.

Drinking water and consuming dietary sources of nitrates/nitrites are speculated to cause increased cancer risks when the nitrate compounds react with amines and amides to form carcinogens. The exact process of how this happens is still being researched. [16]

Related Research Articles

<span class="mw-page-title-main">Nitrate</span> Polyatomic ion (NO₃, charge –1) found in explosives and fertilisers

Nitrate is a polyatomic ion with the chemical formula NO−
3. Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insoluble nitrate is bismuth oxynitrate.

<span class="mw-page-title-main">Fertilizer</span> Substance added to soils to supply plant nutrients for a better growth

A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Many sources of fertilizer exist, both natural and industrially produced. For most modern agricultural practices, fertilization focuses on three main macro nutrients: nitrogen (N), phosphorus (P), and potassium (K) with occasional addition of supplements like rock flour for micronutrients. Farmers apply these fertilizers in a variety of ways: through dry or pelletized or liquid application processes, using large agricultural equipment or hand-tool methods.

<span class="mw-page-title-main">Nitrogen cycle</span> Biogeochemical cycle by which nitrogen is converted into various chemical forms

The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is atmospheric nitrogen, making it the largest source of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems.

<span class="mw-page-title-main">Nitrate vulnerable zone</span> Conservation designation in the UK

A nitrate vulnerable zone is a conservation designation of the Environment Agency for areas of land that drain into nitrate polluted waters, or waterways that could become polluted by nitrates due to environmental and health threats. A nitrate vulnerable zone can be designated as a response to an increase in nitrate leaching or increased use of nitrate fertilizers.

<span class="mw-page-title-main">Sodium nitrate</span> Chemical compound

Sodium nitrate is the chemical compound with the formula NaNO
3. This alkali metal nitrate salt is also known as Chile saltpeter to distinguish it from ordinary saltpeter, potassium nitrate. The mineral form is also known as nitratine, nitratite or soda niter.

<span class="mw-page-title-main">Groundwater</span> Water located beneath the ground surface

Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps, and can form oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology.

<span class="mw-page-title-main">Water pollution</span> Contamination of water bodies

Water pollution is the contamination of water bodies, usually as a result of human activities, that has a negative impact on their uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water pollution results when contaminants mix with these water bodies. Contaminants can come from one of four main sources: sewage discharges, industrial activities, agricultural activities, and urban runoff including stormwater. Water pollution is either surface water pollution or groundwater pollution. This form of pollution can lead to many problems, such as the degradation of aquatic ecosystems or spreading water-borne diseases when people use polluted water for drinking or irrigation. Another problem is that water pollution reduces the ecosystem services that the water resource would otherwise provide.

The nitrite ion has the chemical formula NO−
2. Nitrite is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name nitrite also refers to organic compounds having the –ONO group, which are esters of nitrous acid.

<span class="mw-page-title-main">San Joaquin Valley</span> Area of the Central Valley in California

The San Joaquin Valley is the southern half of California's Central Valley. Famed as a major breadbasket, the San Joaquin Valley is an important source of food, producing a significant part of California's agricultural output.

<span class="mw-page-title-main">Perchlorate</span> Ion, and compounds containing the ion

A perchlorate is a chemical compound containing the perchlorate ion, ClO−4, the conjugate base of perchloric acid. As counterions, there can be metal cations, quaternary ammonium cations or other ions, for example, nitronium cation.

<span class="mw-page-title-main">Atrazine</span> Herbicide

Atrazine is a chlorinated herbicide of the triazine class. It is used to prevent pre-emergence broadleaf weeds in crops such as maize (corn), soybean and sugarcane and on turf, such as golf courses and residential lawns. Atrazine's primary manufacturer is Syngenta and it is one of the most widely used herbicides in the United States, Canadian, and Australian agriculture. Its use was banned in the European Union in 2004, when the EU found groundwater levels exceeding the limits set by regulators, and Syngenta could not show that this could be prevented nor that these levels were safe.

<span class="mw-page-title-main">Soil contamination</span> Pollution of land by human-made chemicals or other alteration

Soil contamination, soil pollution, or land pollution as a part of land degradation is caused by the presence of xenobiotic (human-made) chemicals or other alteration in the natural soil environment. It is typically caused by industrial activity, agricultural chemicals or improper disposal of waste. The most common chemicals involved are petroleum hydrocarbons, polynuclear aromatic hydrocarbons, solvents, pesticides, lead, and other heavy metals. Contamination is correlated with the degree of industrialization and intensity of chemical substance. The concern over soil contamination stems primarily from health risks, from direct contact with the contaminated soil, vapour from the contaminants, or from secondary contamination of water supplies within and underlying the soil. Mapping of contaminated soil sites and the resulting clean ups are time-consuming and expensive tasks, and require expertise in geology, hydrology, chemistry, computer modelling, and GIS in Environmental Contamination, as well as an appreciation of the history of industrial chemistry.

The Turlock Basin is a sub-basin of the San Joaquin Valley groundwater basin which occupies approximately 13,700 total square miles, making it the largest groundwater basin in California. The Turlock Basin makes up 542 square miles of this total. This aquifer is located within Merced and Stanislaus counties in the Central Valley bounded by the Tuolumne River to the north, the Merced River to the south and San Joaquin River to the west. The Sierra Nevada foothills bound the sub-basin to the east. Groundwater in the San Joaquin Valley occurs mostly in younger alluvial material. The Turlock Basin lies to the east of the city of Turlock. Groundwater in the Turlock Basin occurs in older alluvial deposits. Large portions of the San Joaquin Basin have experienced overdraft of water and infiltration of agricultural water pollutants, resulting in poor water quality.

<span class="mw-page-title-main">Nitrogen and Non-Protein Nitrogen's effects on Agriculture</span>

Nitrogen's effects on agriculture profoundly influence crop growth, soil fertility, and overall agricultural productivity, while also exerting significant impacts on the environment.

<span class="mw-page-title-main">Leaching (agriculture)</span> Loss of water-soluble plant nutrients from soil due to rain and irrigation

In agriculture, leaching is the loss of water-soluble plant nutrients from the soil, due to rain and irrigation. Soil structure, crop planting, type and application rates of fertilizers, and other factors are taken into account to avoid excessive nutrient loss. Leaching may also refer to the practice of applying a small amount of excess irrigation where the water has a high salt content to avoid salts from building up in the soil. Where this is practiced, drainage must also usually be employed, to carry away the excess water.

<span class="mw-page-title-main">Agricultural pollution</span> Type of pollution caused by agriculture

Agricultural pollution refers to biotic and abiotic byproducts of farming practices that result in contamination or degradation of the environment and surrounding ecosystems, and/or cause injury to humans and their economic interests. The pollution may come from a variety of sources, ranging from point source water pollution to more diffuse, landscape-level causes, also known as non-point source pollution and air pollution. Once in the environment these pollutants can have both direct effects in surrounding ecosystems, i.e. killing local wildlife or contaminating drinking water, and downstream effects such as dead zones caused by agricultural runoff is concentrated in large water bodies.

<span class="mw-page-title-main">Groundwater pollution</span> Ground released seep into groundwater

Groundwater pollution occurs when pollutants are released to the ground and make their way into groundwater. This type of water pollution can also occur naturally due to the presence of a minor and unwanted constituent, contaminant, or impurity in the groundwater, in which case it is more likely referred to as contamination rather than pollution. Groundwater pollution can occur from on-site sanitation systems, landfill leachate, effluent from wastewater treatment plants, leaking sewers, petrol filling stations, hydraulic fracturing (fracking) or from over application of fertilizers in agriculture. Pollution can also occur from naturally occurring contaminants, such as arsenic or fluoride. Using polluted groundwater causes hazards to public health through poisoning or the spread of disease.

<span class="mw-page-title-main">Reuse of human excreta</span> Safe, beneficial use of human excreta mainly in agriculture (after treatment)

Reuse of human excreta is the safe, beneficial use of treated human excreta after applying suitable treatment steps and risk management approaches that are customized for the intended reuse application. Beneficial uses of the treated excreta may focus on using the plant-available nutrients that are contained in the treated excreta. They may also make use of the organic matter and energy contained in the excreta. To a lesser extent, reuse of the excreta's water content might also take place, although this is better known as water reclamation from municipal wastewater. The intended reuse applications for the nutrient content may include: soil conditioner or fertilizer in agriculture or horticultural activities. Other reuse applications, which focus more on the organic matter content of the excreta, include use as a fuel source or as an energy source in the form of biogas.

Groundwater pollution, also referred to as groundwater contamination, is not as easily classified as surface water pollution. Groundwater aquifers are susceptible to contamination from sources that may not directly affect surface water bodies.

<span class="mw-page-title-main">Wellhead protection program</span> US groundwater contamination law

The Wellhead Protection Program in the 1986 amendments to the Safe Drinking Water Act requires states to protect underground sources of drinking water from contaminants that may adversely affect human health. Over half of the U.S. population relies on groundwater for drinking water However, residential, municipal, commercial, industrial, and agricultural activities can all contaminate groundwater. In the event of contamination, a community's drinking water supply can develop poor quality or be lost altogether. Groundwater contamination occurs from products such as oil, chemicals, gasoline, or other toxic substances to infiltrate groundwater. These products can travel through soil and seep into the groundwater; this process can occur through landfills, septic tanks, mining sites, fertilization, etc. Groundwater contamination might not be detected for a long period of time and health problems can occur from drinking contaminated water. Cleanup of a contaminated underground source of drinking water may be impossible or so difficult it costs thousands or millions of dollars. The U.S. Congress requiring Wellhead Protection Programs by 42 U.S.C. § 300h–7 in the Safe Drinking Water Act applied the concept that it is better to prevent groundwater contamination than try to remediate it. U.S. Congress by 42 U.S.C. § 300h–7 requires identification of the areas that need implementation of control measures in order to protect public water supply wells from contamination as "wellhead protection areas". Communities can use the police power established by the Tenth Amendment to the U.S. Constitution to enforce zoning and subdivision regulations to protect drinking water sources. Thereby communities can direct development away from areas that would pose a threat to drinking water sources.

References

  1. 1 2 3 4 Harter, Thomas (July 2015). "California's agricultural regions gear up to actively manage groundwater use and protection". California Agriculture. 69 (3): 193–201. doi: 10.3733/ca.e.v069n03p193 . ISSN   0008-0845.
  2. 1 2 3 4 "Groundwater Nitrate Sources and Contamination in the Central Valley". California WaterBlog. September 18, 2017. Retrieved May 10, 2018.
  3. ↑ Alexander, Kurtis (June 5, 2018). "Overpumping of Central Valley groundwater has side effect: too much arsenic". San Francisco Chronicle. Hearst Newspapers. Retrieved October 21, 2019.
  4. ↑ "California Agriculture". California Agriculture. 50 (1): 2. January 1996. doi: 10.3733/ca.v050n01p2 . ISSN   0008-0845.
  5. ↑ Idaikkadar, N.M. (1979), "Agricultural Production – Livestock and Livestock Products", Agricultural Statistics, Elsevier, pp.  53–68, doi:10.1016/b978-0-08-023388-8.50012-4, ISBN   9780080233888
  6. ↑ Shrestha, Anil; Luo, Wei (September 26, 2017). "Analysis of Groundwater Nitrate Contamination in the Central Valley: Comparison of the Geodetector Method, Principal Component Analysis and Geographically Weighted Regression". ISPRS International Journal of Geo-Information. 6 (10): 297. Bibcode:2017IJGI....6..297S. doi: 10.3390/ijgi6100297 . ISSN   2220-9964.
  7. ↑ "Groundwater in California - Public Policy Institute of California". Public Policy Institute of California. Retrieved May 10, 2018.
  8. ↑ Olmstead, Alan; Rhode, Paul W. (July 16, 2018), "Agriculture in American Economic History", The Oxford Handbook of American Economic History, vol. 1, Oxford University Press, pp. 158–182, doi:10.1093/oxfordhb/9780190882617.013.8, ISBN   9780190882617
  9. 1 2 Nelson, Timothy; Chou, Heidi; Zikalala, Prudentia; Lund, Jay; Hui, Rui; Medellín–Azuara, Josué (March 23, 2016). "Economic and Water Supply Effects of Ending Groundwater Overdraft in California's Central Valley". San Francisco Estuary and Watershed Science. 14 (1). doi: 10.15447/sfews.2016v14iss1art7 . ISSN   1546-2366.
  10. ↑ Aichele, Stephen S. (2004). "Arsenic, nitrate, and chloride in groundwater, Oakland County, Michigan". Fact Sheet. doi:10.3133/fs20043120. ISSN   2327-6932.
  11. 1 2 Balazs, Carolina; Morello-Frosch, Rachel; Hubbard, Alan; Ray, Isha (September 2011). "Social Disparities in Nitrate-Contaminated Drinking Water in California's San Joaquin Valley". Environmental Health Perspectives. 119 (9): 1272–1278. doi:10.1289/ehp.1002878. ISSN   0091-6765. PMC   3230390 . PMID   21642046.
  12. ↑ Sheehy, Robert D. (2006). "Stale-Dated Check Fraud: How Much Has Your City Lost?". doi:10.1037/e559052006-004.{{cite journal}}: Cite journal requires |journal= (help)
  13. ↑ "Nonpoint and Point Sources of Nitrogen in Major Watersheds of the United States". 1994. doi: 10.3133/wri944001 . hdl: 2346/64037 .{{cite journal}}: Cite journal requires |journal= (help)
  14. ↑ Ward, Mary H.; Kilfoy, Briseis A.; Weyer, Peter J.; Anderson, Kristin E.; Folsom, Aaron R.; Cerhan, James R. (May 2010). "Nitrate Intake and the Risk of Thyroid Cancer and Thyroid Disease". Epidemiology. 21 (3): 389–395. doi:10.1097/EDE.0b013e3181d6201d. ISSN   1044-3983. PMC   2879161 . PMID   20335813.
  15. ↑ De Roos, Anneclaire J.; Ward, Mary H.; Lynch, Charles F.; Cantor, Kenneth P. (November 2003). "Nitrate in Public Water Supplies and the Risk of Colon and Rectum Cancers". Epidemiology. 14 (6): 640–649. doi: 10.1097/01.ede.0000091605.01334.d3 . ISSN   1044-3983. PMID   14569178. S2CID   37319996.
  16. ↑ Ward, M. H.; Mark, S. D.; Cantor, K. P.; Weisenburger, D. D.; Correa-Villaseñor, A.; Zahm, S. H. (September 1996). "Drinking water nitrate and the risk of non-Hodgkin's lymphoma". Epidemiology. 7 (5): 465–471. doi: 10.1097/00001648-199609000-00003 . ISSN   1044-3983. PMID   8862975. S2CID   42375910.
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