PROJ00026

• Contract/PO #: C153412
• Contractor Name: Louisville, City of
• Contract Type: Loan
• Water District: 6
• County: Boulder
• Bill Number: HB 83-1102
• Loan Projects - Doc Type: Feasibility Study

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be filled either from direct flow diversions from South Boulder Creek via the
Community Ditch and Louisville Lateral, direct flow diversions through a by-pass
from the E1dorado Springs pipeline, or deliveries from Marshall Lake. Only sporadic
water quality data was available for South Boulder Creek upstream of the Eldorado
Springs pipeline point of diversion, however Table 10 shows water quality data
for Marshall Lake.
Each of the proposed storage alternatives at Harper Lake would have an
average depth of 18 feet. Shallow reservoirs such as this are subject to periodic
turnover from aerobic to anaerobic conditions in the fall which can possibly
create taste, odor and potential bacterial or virus problems. However, anaero-
bic conditions could be avoided in the Harper Lake facility by periodically
treating the lake with copper sulfate and alum as is presently done in Louisville
Reservoir. As an additional measure to reduce the possibility of anaerobic
conditions, it is recommended that a by-pass be constructed from the Eldorado
Springs pipeline to the Harper Lake storage facility. This would allow for
year-round circulation of water in Harper Lake. Without the pipeline by-pass,
circulation would only occur during the irrigation season when deliveries are
being made through the Louisville Lateral.
By constructing the by-pass pipeline and periodically treating the water
in Harper Lake with copper sulfate, the water quality in Harper Lake would be
expected to be similar to that of Louisville Reservoir. Louisville Reservoir
is approximately 20 to25 feet deep at its deepest point and has an average depth
of 12.5 feet. In spite of its shallow depth, the overall water quality in Louis-
ville Reservoir is considered to be well within acceptable limits for municipal
raw water supplies, due primarily to periodic treatments with copper sulfate
and maintenance of circulation through the lake with water deliveries from the
Eldorado Springs pipeline.

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