Summary of major issues and findings
Are streams and ground water being contaminated by nutrients and
bacteria? (p. 6)
Nutrient concentrations in streams are higher in areas with greater
agricultural land use or downstream from wastewater-treatment plants
than in forested areas. These higher concentrations may result in
increased algal growth in streams.
Nutrient concentrations in ground water are higher in areas with
greater agricultural land use than in forested areas. These higher
concentrations seldom exceed drinking-water standards.
Bacteria concentrations in streams are higher in basins with greater
agricultural land use (mostly pasture). Fecal coliform bacteria
concentrations occasionally exceed State water-quality standards
for whole-body contact recreation.
Nutrient and bacteria concentrations are affected by hydrologic and
geologic factors. Stream discharge and the presence or absence of
confining geologic layers are two factors that are important in
Are pesticides and other organic compounds more prevalent in the water,
bed sediment, and fish or clam tissue from some land-use settings than
from other settings? (p. 10)
In streams and ground water, pesticides were more prevalent in
agricultural areas than in forested areas. Concentrations generally
were low and seldom exceeded U.S. Environmental Protection Agency
drinking-water criteria or standards, or criteria for the protection
of aquatic life.
In bed sediment, the greatest numbers of pesticides and other
organic compounds generally were detected at sites downstream from
urban areas. No concentrations exceeded U.S. Environmental Protection
Agency criteria for the protection of aquatic life.
In biological tissue, pesticides were detected at 5 of 26 stream
sites. Chlordane was detected downstream from Springfield, Mo. DDT,
DDE, or dieldrin was detected at four sites in agricultural basins.
Are historical or active mining sites affecting the quality of surface
water? (p. 12)
Concentrations of sulfate and some trace elements in water from
streams in areas of active or historical lead-zinc mining tend to be
higher than in areas where mining has not occurred. These trace
element concentrations decrease with increasing distance downstream
from the mining activity. Concentrations usually did not exceed
Federal standards or criteria for the protection of drinking water,
human health, or aquatic life.
Concentrations of lead and zinc in bed sediment and fish or clam
tissue are substantially higher at sites with mining activities
(historical or active) in the basin. Concentrations are high enough to
suggest potential adverse biological effects. The State of Missouri
has issued a fish consumption advisory for some streams.
Are naturally occurring radionuclides present in ground-water supplies?
Radium (a product formed by the radioactive decay of uranium) is
present in the confined part of the Ozark aquifer. However, the levels
of radium seldom exceeded the U.S. Environmental Protection Agency
Radon (a gas produced by the radioactive decay of radium) levels
exceeded a proposed (but withdrawn) U.S. Environmental Protection
Agency drinking-water standard in nearly one-half of the samples.
Radon can enter homes through their water systems. Homes served by
private domestic wells and small public waterworks using ground water
can be particularly vulnerable.
Radon levels are greater in the Springfield Plateau aquifer and the
unconfined part of the Ozark aquifer than in the confined part of the
What are some factors that affect aquatic (instream and riparian)
habitats of Ozark streams?
Several factors can affect aquatic habitats, which then affect
biological communities. Many habitat characteristics appeared to be
influenced more by basin size than by land use.
Small streams in agricultural areas generally have fewer trees and
other woody plants in the riparian zone than do small streams in
forested areas. This results in more sunlight reaching the streams in
the agricultural areas. More sunlight and the higher nutrient
concentrations probably result in faster growing attached algae in
Some other habitat characteristics were different between the
agricultural and forested sites studied. Of these characteristics,
some are not likely the result of agricultural practices, while
others (canopy angle, channel width, and sinuosity) may, at least in
part, result from agricultural practices. These characteristics can
affect biological communities.
Although the effects of instream gravel mining in the Ozarks were
not studied by the NAWQA Program, some studies suggest that gravel
mining has detrimental effects on instream habitat.
Are fish communities being affected by land-use activities?
Stonerollers make up a greater percentage of the fish at
agricultural sites than at forested sites. Stonerollers graze on algae
attached to rocks and other surfaces. More algae probably grow on
these surfaces because of the higher nutrient concentrations and
greater amounts of sunlight reaching these streams.
Sunfish (including the black basses) and darters make up a smaller
percentage of fish at agricultural sites than at forested sites.
Members of the sunfish family (particularly smallmouth bass) are
important game fish. Several species of darters that live in the
Ozarks exist nowhere else in the world.
Fish community composition appears to be related to stream size,
canopy angle, substrate, and water chemistry. Some of these factors
are affected by human activities.
Petersen, J.C., Adamski, J.C., Bell, Davis, J.V., Femmer, S.R., Freiwald, D.A., and Joseph, R.L., 1998, U.S. Geological Survey Circular 1158, on line at < URL: http://water.usgs.gov/pubs/circ1158>, updated April 3, 1998
This page is a subpage of <URL:http://water.usgs.gov/pubs/circ1158>
Email questions and comments to GS-W_NAWQA_Outreach@usgs.gov
Last modified: 4/3/98