History of Ground Water Law 

California ground water law is complicated. Ground water is classified as either percolating ground water or as a subterranean stream.

Ground water not flowing as a subterranean stream is classified as percolating ground water.

When the flow of ground water is confined to a known and defined subsurface channel it is a subterranean stream.

The California Supreme Court established the doctrine of correlative water rights in 1903 that stated overlying users of percolating ground water and riparian users of subterranean streams must share the available supply. If a shortage exists, each overlying or riparian right holder must cut their use to some degree. Overlying and riparian users have priority over appropriators who may take only surplus water.

Percolating ground water is subject to different laws (known as ground water law) and recognizes two general types of rights, overlying and appropriative. Subterranean streams are subject to surface water law that recognizes two general types of rights:

• Riparian: inherent with ownership of overlying land.
• Appropriative: based on the concept of 'first in time, first in right' with a priority date that determines the seniority of the right.

Ground water also can be appropriated and diverted outside of ground water basins by cities, water districts, and other users whose lands do not overlie a ground water basin. In 1914, California created a water right permit process governing the appropriation of surface water and subterranean streams.

Appropriations of subterranean streams require a permit from the State Water Resources Control Board. The method for appropriating percolating ground water is to simply pump the water and put it to reasonable beneficial use. No state permit is required.

Ground Water Overdraft
Long term overpumping of ground water that exceeds natural or artificial replenishment has long been a concern. Known as ground water overdraft, many areas affected in the past have been corrected, but others still exist today. Overdrafting occurs primarily in the San Joaquin Valley and in coastal areas. Although not a serious ongoing problem in Sonoma County, overdrafting has occurred in the vicinity of Rohnert Park and areas of the county where replenishment or ground water movement is slow.

Overdrafting a ground water supply is costly and may result in increased pumping, deepening or drilling new wells, poorer water quality; and reduced aquifer capacity.

Quality
Surface water may become polluted more quickly and readily, but it is better equipped to handle pollution. Exposure to air and sunlight of a swift-moving stream causes some pollutants to evaporate, be consumed or rapidly diluted by aerobic (oxygen-using) bacteria.

Ground water lacks the natural self-cleansing abilities of streams and rivers. Under the aquifer’s anaerobic conditions, the environment is relatively bacteria-free and the temperature fairly constant. The lack of turbulence in slowly moving ground water allows the transport of pollutants through the system as a "plume" rather than dispersing and diluting contaminants. With the introduction of new chemical compounds into the environment and major advances in detection technology, traces of unfiltered chemicals are discovered in wells nationwide.

Seawater Intrusion
When ground water is pumped from a coastal aquifer faster than it can be replenished from surface sources, seawater intrudes and contaminates the aquifer. Areas in Sonoma Valley and Petaluma Valley adjacent to San Pablo Bay have experienced growing saline contamination.

Nitrate
Nitrate is widely used as a fertilizer and occurs in animal manure and septic system effluent. Nitrate is not filtered out by the soil and percolating water can transport nitrate from these sources to ground water. It also may migrate with the water into poorly constructed wells. High nitrate levels can cause a potentially fatal condition in infants called methemoglobinemia, or 'blue-baby" syndrome. Areas in eastern Petaluma are contaminated with nitrogen compounds from previous poultry operations.

Industrial and Agricultural Chemicals
The number of household, industrial, and agricultural chemicals has risen dramatically since World War II. More new substances are introduced into the environment each year as we seek to increase the productivity of agriculture and make our lives more comfortable.

Various areas in Sonoma County have groundwater contaminated with hazardous materials or chemicals. In some cases, pollution is relatively stable and does not spread beyond the contamination site. In other circumstances, pollution travels for significant distances in ground water, increasing the problems as it goes.

Top of Page

Back To Water Quality