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GLIN==>> Many Contaminants Found in Nation's Streams, But Few Drinking-Water Standards Exceeded, USGS Report Shows

Posted on behalf of Gail Wendt <gwendt@usgs.gov>

News Release
U.S. Department of the Interior
U.S. Geological Survey
Water Resources Division
439 National Center
Reston, VA 20192

NAWQA Contact: Tim Miller

General Contact: Gail Wendt

For release: June 28, 1999


        In a look at water-quality conditions of 20 of the country's largest
and most important river basins,  the U.S. Geological Survey announced today
(June 28, 1999) that streams in areas with significant agricultural or urban
development almost always contain complex mixtures of nutrients and

        The complex nature of those chemical mixtures and the lack of
current human and aquatic health criteria to determine risk of exposure,
make addressing these issues a top national priority.

        Secretary of the Interior Bruce Babbitt said, "Over the last two
decades, our nation has made great progress in improving water quality and,
yet, as the USGS report points out, major challenges remain in protecting
our aquatic resources.

        "The widespread occurrence of pesticides and nutrients in water
documented in the USGS report underscores the need to devote more attention
to the quality of our waterways and the life that depends on them," Babbitt

        The good news is that concentrations of individual pesticides in
from wells and as annual averages in streams were almost always lower than
current U.S. Environmental Protection Agency drinking-water standards and

        The USGS assessment results suggest that aquatic life may be more at
than humans from these contaminants.  More than one-half of agricultural and
urban streams sampled had concentrations of at least one pesticide that
exceeded a guideline for the protection of aquatic life.

        The potential risk to people and to aquatic life can only be
partially addressed, based on available standards and guidelines.  The
health picture is made more complex by the lack of standards or guidelines
for many pesticides and their "breakdown" products or metabolites.  Adding
to the complexity is the fact that existing standards and guidelines were
developed for individual chemicals and do not take into account exposure to
mixtures of chemicals and seasonal pulses of high concentrations.

        USGS analysis of almost every stream sample and about one-half of
the well samples detected the presence of two or more pesticides.  The
ability of the USGS to "detect" these chemicals in water samples does not
automatically translate into impacts on human or aquatic health.  (The level
of accuracy demanded by the USGS to assess the effects on water quality is a
minute amount -- sometimes parts per trillion -- that is well below the
threshold used for setting standards and guidelines.)

        In addition, potential effects on reproductive, nervous and immune
systems, as well as on chemically sensitive individuals, are not yet well
understood.  For example, some of the most frequently detected pesticides
are suspected endocrine disrupters that have potential to affect
reproduction or development of aquatic organisms or wildlife by interfering
with natural hormones.

        "Despite considerable progress in the four decades since Rachel
Carson warned the nation of the risks posed by environmental contaminants, a
large range of nutrients and other contaminants continue to enter our
waterways, said Mark Schaefer, deputy assistant secretary for water and
science at the Interior Department, in commenting on the report.

        "The President's Clean Water Action Plan lays out a blueprint for
addressing the nation's water-quality problems," Schaefer said.  "The
challenge is to find ways to work cooperatively to reduce urban and
agricultural contaminants on a watershed-by-watershed basis.

        Schaefer pointed to the report's implication that understanding
patterns of
contamination in relation to land use, pesticide use and the natural
characteristics of hydrologic systems can help reduce the amounts of
pesticides that reach streams and ground water.  Of the urban streams
studied by the USGS, nearly every one had concentrations of insecticides
that exceed guidelines for protection of aquatic life, which shows this is
not just an agricultural problem.

       Turning to nutrients, the USGS report said that nitrate generally
does not pose a health risk for people whose drinking water comes from
streams or from aquifers (water-bearing rock formations) buried relatively
deep beneath the land.

        Protection of human health is more difficult in rural agricultural
areas where shallow ground water is used for domestic water supply.  High
levels of nitrate in shallow ground water also may serve as an "early
warning" of possible future contamination of older underlying ground water,
which is a common source for public water supply.

        Looking at the aquatic environment, concentrations of nitrogen and
phosphorus commonly exceed levels that can contribute to excessive growth of
algae and other nuisance plants in streams.  Such growth can clog water
intake pipes and filters and interfere with recreational activities, such as
fishing, swimming and boating.  The subsequent decay of the algae can result
in foul odors, bad taste in drinking water and low dissolved oxygen in
aquatic habitats -- oxygen that is necessary for fish and other aquatic life
to survive.

       The USGS report is based on analysis of data collected from 20 major
river basins and aquifer systems across the country.  The report, The
Quality of Our Nation's Waters--Nutrients and Pesticides, published as USGS
Circular 1225 is available on the World Wide Web as downloadable portable
document files (PDF) at: <http://water.usgs.gov/pubs/circ/circ1225/> or in
printed form (single copies of the report are at no cost) from: Branch of
Information Services, P.O. Box 25286, Denver, CO  80225, or by fax request
to:  303-202-4693.  Please specify USGS report C-1225.

        As the nation's largest water, earth and biological science and
mapping agency, the USGS works in cooperation with more than 2,000
organizations across the country to provide reliable, impartial, scientific
information to resource managers, planners, and other customers. This
information is gathered in every state by USGS scientists to minimize the
loss of life and property from natural disasters, contribute to the sound
conservation, economic and physical development of the nation's natural
resources, and enhance the quality of life by monitoring water, biological,
energy and mineral resources.


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        (Note to Editors: See attached "highlights" for further information
on the
USGS water- quality report.)

        Selected highlights and implications of the USGS water-quality

*  IT'S ALL RELATIVE--The types and relative levels of concentrations of
nutrients and pesticides found in streams and ground water are closely
linked to land use and the chemicals applied in each setting.  Some of the
highest concentrations of nitrogen and herbicides, including those most
heavily used (such as atrazine, metolachlor, alachlor and cyanazine) were
detected in USGS samples collected from streams and shallow ground water in
agricultural areas.  Some of the highest concentrations of phosphorus and
insecticides (including diazinon, carbaryl and malathion) were found in
urban streams.

*  LINGERING LEGACY--The mixtures of contaminants found in the USGS study
include chemicals that are no longer in use, such as DDT, which was banned
in the early 1970's.  These persistent insecticides still are found at
elevated levels in fish and streambed sediment in many urban and
agricultural streams across the Nation. But there is good news in that there
has been a national reduction in concentrations of these organochrlorine
insecticides (DDT, dieldren and chlordane) in whole fish.  Concentrations of
DDT in sediments also have decreased, as indicated in sediment-core samples
from urban and agricultural reservoirs and lakes.

*  TIMING IS EVERYTHING--Seasonal patterns in water quality of streams
emerged in most basins in the USGS study.  The patterns reflect many
factors, but mainly the timing and amount of chemical use.  Other influences
are the frequency and magnitude of runoff from rainstorms or snowmelt.
Specific land-management practices, such as irrigation and tile drainage
also affect water quality.  Concentrations of nutrients and pesticides are
highest during runoff following chemical applications.  The seasonal nature
of these factors dictate the timing of elevated concentrations in
drinking-water sources and aquatic habitats and serve as a guide in
developing water management strategies.

* LAY OF THE LAND MATTERS--Local geography and natural features, including
topography, geology, soils, hydrology and climate, affect the occurrence of
nutrients and pesticides in water.  Add the influence of land-management
practices like tile drainage, irrigation and conservation strategies, and it
matters a great deal as to where you are in the country
as to what the impacts are on water quality, the USGS report said.

* * * USGS * * *