WMOD00423

• Title: Currents…Developing Technology for Tomorrow's Challenges
• Date: 1/1/1993
• Weather Modification - Doc Type: Report

mining drain into portions of the basin,
resulted in water quality degradation. One
of the most significant sites contributing
heavy metals to the river is the LMDT
(Leadville M.ine Drainage Twmel) located
near Leadville, Colorado. This discharge
was acquired by Reclamation in 1959 to
obtain the associated water rights. To bring
the discharge into compliance with the
Clean Water Act, water treatment plant
construction started in the spring of 1990.
This plant was operational by the spring of
1992.
As part of the monitoring plan for track-
ing the cleanup of the LMDT and the river,
macroinvertebrates above and below this
drain have been collected. Data from 1991,
before the completion of the treatment
plant, are presented in table 1 and demon-
strate the ability of biosurvey data to
discriminate between levels of impairment.
As the plant continues to operate and to
remove heavy metals, the macroinverte-
brate community below the drain is
expected to show improvement. As early
as July 1992, the community score at sta-
tion "C" had improved from 39 to 52
percent of the reference station.
The scores of these analyses are based
on work done with the various metric
indexing procedures by the EP A and
others.

Bioassays

In another study, bioassays were used to
evaluate impacts of rubber tires on water
quality. Recent studies by Reclamation
have quantified the value of tire reefs to
developing fisheries in canals. In the past,
the effects of tires on the aquatic environ-
ment have not been studied in detail
because of the obvious presence of fishes
and other aquatic organisms that make use
of these reefs. As part of the Reclamation
study, however, it was decided to deter-
mine whether toxicity might be associated
with tires and what the toxin, if present,
might be. Earlier chemical tests had indi-
cated that a wide array of organic and
inorganic chemicals were associated with
tires. TIE procedures were used in this
case to characterize toxicity.

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Initially, a tire leachate was prepared by
soaking tire plugs in water for 31 days.
Toxicity tests were then conducted using
both the C. dubia and the fathead min-
nows. Toxicity characterization consisted
of a baseline toxicity test with a series of
dilutions of tire leachate water, along with
aeration, filtration, SPE (solid phase extrac-
tion) tests, and pH adjusted samples to test
for volatiles, particulate bound toxicants,
nonpolar organic compounds, and changes
in metal bioavailibility, respectively. Sam-
ples were also treated with EDT A
(ethylenediaminetetraacetate) or sodium
thiosulfate to assess metals toxicity.
Results are presented in table 2. The
leachate was acutely toxic to the C. dubia
but not to the fathead minnows. Sample
toxicity reduction associated with charac-
terization tests, along with differences in
species susceptibility, indicated that metals
were present in toxic concentrations. Toxic-
ity was partially removed by sodium
thiosulfate and totally removed by EDT A,
indicating metal toxicity and a mixture of
metals. Toxicity was also partially re-
moved by SPE but this toxicity was not
eluted from SPE using methanol, which
provides additional evidence that metals
were the toxin. Later chemistry analyses
confinned the presence of zinc and copper
in concentrations that could be toxic.
This study does not impinge upon the
value of using tire reefs as habitat for
fishes, because the tested material was
highly concentrated. The study may, how-
ever, provide important information on
number of reefs that may be suitable for a
given area.
One important goal of the Strategic Plan
for Reclamation is to manage resources to
protect and provide for safe and reliable
water supplies for multiple uses. The use
of biomonitoring in assessing our water
resources is a valuable tool, and its impor-
tance will undoubtedly continue to be
demonstrated in the future.