Over the years, many types of chemicals have gotten into our waterways—and they
continue to do so today. Chemical water pollution typically occurs because …

• the chemicals were dumped into the water intentionally;
• the chemicals seeped into groundwater, streams, or rivers because of failing pipes or storage tanks;
• the chemicals catastrophically contaminated waterways because of industrial accidents;
• the pollution settled out of polluted air (or was precipitated out of polluted air); or
  chemicals were leached out of contaminated soil.

The above types of chemical contamination are considered “point sources” of water
pollution. Non-point-source chemical pollution also occurs via pesticide runoff from
farm fields and homeowners’ lawns, as well as runoff of automotive fluids and other
chemicals from roads, parking lots, driveways, and other surfaces.

It’s beyond the scope of this article to document the effect of every chemical that
has ever polluted water, but it’s easy enough to point out a few things:

- Severe chemical spills and leaks into surfaces waters usually have an immediate
effect on aquatic life (fish kills, etc.).

- Chronic lower-level chemical pollution has more subtle effects, with problems
manifesting over a long period of time and sometimes being difficult picture of dead
fish in polluted water to tie directly to the water pollution.

-The human effects of chemical pollution in water can generally be viewed the same
as any other form of chemical contamination—water is just the delivery mechanism.

There are a few broad categories of water pollution effects related to chemicals

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