California’s most ubiquitous and widely used resource is groundwater, which is massively misused and misunderstood. Water and contaminant are collected and stored by aquifers in large areas over decades to serve many activities of the citizens and the ecosystems. Therefore, finding groundwater in California and preserving it has become a notice of utmost importance.
Groundwater is significant in many ways for California. Approximately 30% of California's water supplies come directly from groundwater, with much more in years of drought. Urban and rural areas depend solely on this resource of water. California public 85% of times depend on groundwater for the drinking purpose.
The groundwater storage capacity of the State is more than 10 times of all the reservoirs present. Groundwater extracts some but not all sources of toxins from drinking water. Gradually, groundwater also adds contaminants, predominantly salts and nitrate. Groundwater pumping capacity is about 2% of the electricity consumption in California. Several native species, assisted by high groundwater tables, rely on stream flows and wetlands fed by springs. Multi-faceted reliance on groundwater in California contributes to numerous disputes and misconceptions.
Groundwater arises from surface water, recharging the natural landscape and providing water for irrigation. When pumping surpasses recharge, the capacity of the aquifer will be exhausted. Recharge from streams happens when the level of groundwater is below the surface. The natural landscape and water recycling for irrigation take place as wasted water seeps into the plant and crop root zone.
Percolation is important for habitats and crops. The root zone can accumulate salinity without some amount of percolation, which ultimately kills plant life. In some places, injection wells, recharge basins, and irrigation systems are used to actively recharge groundwater during rainy years or winters for long-term storage and use during dry periods or summer.
Groundwater pumping in much of California has drastically lowered groundwater echelons, which frequently increases stream recharge. Enlarged losses from streams to groundwater (unless controlled by upstream dams) can reduce downstream flows and disturb ecosystems. Eventually, almost all the groundwater used for irrigation and drinking water would have become stream flow unless it is properly regulated by the drainage system.
Today, overdraft occurs in many parts of the Central Valley, California, especially the Tulare Lake Basin, accompanied by some southern and coastal California basins with small reservoirs of water sources and intensive agriculture. Some overdraft temporarily reverses during the period of the rainy session, which resulted in more surface water deliveries.
Overdraft has been reduced in much of the Sacramento Valley due to increased filtration from streams caused by lower groundwater tables. A major regional and statewide problem is the long reliance of the Tulare Lake Basin on the Delta and the overdraft for about 60% of its water supplies. The Tulare Lake Basin consumes more water than any other region in the California area (about 8 million acre-feet per year).
Nitrate contamination is one of the most serious groundwater issues worldwide, specifically in California, as it is impacting the availability of drinking water in many rural or traditionally agricultural areas. While it affects even big cities like Fresno, nitrate pollution is most costly for small rural water supplies including over 200,000 people in the small household in the Salinas basins and Tulare.
Most nitrate pollution is caused by agricultural fertilizers, septic tanks, etc. Some agricultural areas should anticipate nitrate contamination in drinking water. Due to the large extent of contamination and traveling in groundwater, source control of nitrate discharge is only a partial long term solution.
Providing solutions for drinking water sand compensation in today’s time and the foreseeable future is an inevitable and urgently needed response.
Drinking water nitrate problems are often compounded by naturally occurring chromium, arsenic, uranium and other contaminants in the groundwater.
Another long-term threat to groundwater quality is Salinity Accumulation. Salt accumulation is mainly challenging on the west side of the Tulare Lake and San Joaquin basins, lacking the capacity to extract salt from local soil or imported water, impacting approximately 500,000 acres of agricultural land.
In many states of California, salt accumulation in groundwater threatens the viability of urban groundwater usage, due to wastewater protocols related to higher salinity in urban wastewater releases. Water irrigation, Natural soils and aquifers, animal farming, and industrial waste are the major sources of salt across the state. Salt in irrigation water and wastewater that are sprinkled on crops or urban sceneries are absorbed by plants, leaving behind the salt as residue. Accumulation of salinity has a tradition of ending agricultural production, especially in arid regions.
In some places, especially in the Tulare Lake and San Joaquin basins, the land subsidence resulting from groundwater use has been substantial. In the middle of the 20th century, land subsidence fluctuated from a few feet to over 30 feet. It is persistent due to declining levels of groundwater and remains a problem in these regions. Even though, insufficient investigation of the occurrence and subsides implications and finances of the long-term lucrative costs has been carried out. Regional subsidence on canal and drainage systems can, however, incur potentially large costs from floods and inadequate slopes.
