| dc.description.abstract | Recent initiatives by the U.S. Environmental Protection Agency will
bring stormwater runoff from large metropolitan areas under the purview of
state water quality agencies. Yet, there is little information concerning the
toxicological effects of stormwater runoff on aquatic biota on which to base
new regulations. This study addressed acute and short-term chronic effects
of stormwater runoff to aquatic biota in an urban stream, Lincoln Creek, in
Milwaukee, Wisconsin. Samples of stormwater and baseflow for acute and
short-term chronic tests were collected during runoff events and baseflow
beginning with snowmelt March-October, 1 993. Stormwater samples were
collected with a stream gauge-actuated automatic sampler programmed to
collect up to eight sequential samples from the stream during each runoff
event. Baseflow samples were a grab collected every other week from the
drop structure located at 47th Street and Congress Avenue. A total of 24
runoff events and 1 2 biweekly baseflow samples were tested. A total of
316 laboratory toxicity tests were performed on serial dilutions of the
stormwater runoff with Ceriodaphnia dubia, Daphnia magna and Pimephales
promelas. In addition, 34 in-situ toxicity tests, fish and macroinvertebrate
assemblages indigenous to Wisconsin were exposed in flow-through aquaria
housed in a U.S. Geological Survey gauging station adjacent to Lincoln
Creek.
The short-term (less than 8 days) toxicity tests used in this study
appear to have underestimated toxic effects of Lincoln Creek stormwater.
The short term, acute or 7-day chronic toxic effects, which could be solely
attributed to stormwater runoff, were identified with the three laboratory
test species. In-situ acute tests with 23 families of macroinvertebrates (2-
day) and 10 species of fish (7-day) detected only slight toxicity for some
species. Significant mortality in Rhinichthyes atratulus, possible caused by
stormwater or baseflow water quality, occurred in one of 26 tests with
indigenous fish. Significant mortality in the caddisfly family Hydropsychidae
occurred in one of 8 tests. It appears conventional short-term toxicity tests
which include the 7-day Ceriodaphnia dubia reproductive test lack the
sensitivity to detect the type of biological degradation seen in Lincoln Creek.
Test organisms were exposed to a variety of metal contaminants in
stormwater and baseflow samples at levels that exceeded Acute Toxicity
Criteria and Chronic Toxicity Criteria values for metals established by
Wisconsin Department of Natural Resources. Polycyclic aromatic
hydrocarbon concentrations in stormwater runoff were much greater than at
baseflow for samples collected from Lincoln Creek and were found at
concentrations that are reported toxic to aquatic life. Although little acute
mortality was recorded, there was evidence that longer exposure produced
extensive mortality that could in part explain the paucity of aquatic biota in
Lincoln Creek. Juvenile and adult Pimephales promelas exposed on-site to
Lincoln Creek water for greater than 14 days suffered substantial mortality.
Chronic (greater than 14 days) toxicity tests are more sensitive and appear
better suited to identify biological impairment caused by stormwater runoff. | en_US |
