PUB00111

• Year: 1996
• Title: Layperson's Guide to Water Pollution
• CWCB Section: Interstate & Federal
• Author: California Water Education Foundation
• Description: Layperson's Guide to Water Pollution
• Publications - Doc Type: Other

farms. Similarly, treated sewage and eroded soils
can have the same consequence on streams, lakes
and bays - loading water with phosphorus and
nitrogen that feeds algae and consumes oxygen as
organic matter decomposes.

Despite these complexities, the sum
of these problems is more discern-
ible. EPA officials believe nonpoint
pollution is the single biggest reason
that California and the nation have
not met water quality standards. In a
comprehensive nationwide study
sponsored by EPA and completed in
1986, nonpoint source pollution was
found to compromise the beneficial
uses of 65 percent of streams,
76 percent of lakes and 45 percent
of estuaries. More recent state
studies blame nonpoint pollution
for 50 percent to 80 percent of
California's remaining water pollution
problems.

But unlike well-defined municipal and industrial
discharges, the character and concentration of
nonpoint sources can vary from year to year and
storm to storm. It often is harder for researchers to
track and prove the consequences associated with
nonpoint sources - such as the chronic effect of
metals on fish reproduction, or the acute but short-
lived toxicity of pesticides washed into streams by
heavy storms. These complexities complicate efforts
to regulate effective solutions.

Scientists are only
beginning to fully
understand the dynamics
of lIonpoiflt source
pollution.

Agriculture is one of
the largest land users in
California and/ant/fields are
a major source (~f/ertilizer,
pesticides and Nher chemicals
found in the state's rivers,
lakes and streams.

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In California, as throughout the West, the dry climate
and episodic character of precipitation also shape
the consequences of non point pollution. Only one
in four miles of rivers in California flow year-round,
and the first storm after a long dry spell can wash
more pollutants into streams than a similarly sized
storm in the middle of a wel winter.

Much of the water that does not run off the land
soaks into it, carrying contaminants on the surface
and in the soil down into groundwater aquifers.
Agricultural and industrial chemicals, animal wastes,
landfills, old mines, 28,000 underground tanks that
are known to be leaking, and an unknown number
of failing septic systems, all have the potential to
contaminate groundwater that is tapped to meet the
state's urban and agricultural water needs. In some
places, polluted groundwater makes
its way into streams, such as indus-
trial solvents that have been detected
in the American River. But because
most aquifers are more confined than
rivers, eliminating the pollution
quickly can require active treatment
efforts - an enormously expensive
process of extracting and cleaning
the most contaminated water.