WSP01843

• File Number: 5000.100
• Description: Flood Protection Section - Coal Creek Project
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 7/21/1980
• Author: City of Louisville
• Title: City of Louisville - Coal Creek Proposal
• Water Supply Pro - Doc Type: Report/Study

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001743

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mg/l, yet there are no fish. In other words, ammonia level s
and fish abundance do not coincide very well.

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There are two possibilities. First, ammonia may be a
major factor affecting fish due to ammonia spikes or to changes
with the seasons in the ability of the stream to metabolize
ammonia. This is purely speculative, however. A second and
very real possibility is that ammonia is never a major
cons iderat ion, but other factors are. Among the observed
factors, streambed condition and severe turbidity could
definitely contribute to degradation, but are not likely to
wipe out a fish fauna. Other factors which were not "observed
such as the presence of toxins in some of the point or nonpoint
sources or nocturnal oxygen depletion due to high BOD could be
involved. We have no information on these aspects of the
stream. For any of these factors, Louisville might contribute
in either a major or a minor way.

In summary J the poor cend it ions for fish in the lower
reaches of Coal Creek cannot be explained by the observed
ammonia levels in my opinion, but may be explained by high
ammonia levels during certain seasons or by other factors which
have not been studied.

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Summary and Recommendations. Coal Creek may lack the
characteristics of a class 1 stream throughout the warmwater
segment. In the upper reaches of the warmwater segment, Where
the arguments for classification of this type are strongest,
the very low flow at certain times of the year and complete
absence of game fish are disturbing. Beginning above the
Louisville effluent, the stream experiences degradation of
several kinds due to nonpoint sources. This is exacerbated
downstream to the extent that virtually no fish exist below the
City of Louisville at the present time. Although the specific
cause for the absence of fish below Louisville is not clear,
the causes of degradation are obviously several, including poor
streambed condition, low stream flow at certain times of the
year, very high turbidity, ammonia levels sufficient to have
nonlethal effects on fishes, and possibly other factors
that are presently unknown. In my opinion, all of these
problems would have to be dealt with in order to bring the
warmwater portion of Coal Creek into the class 1 definition.
This would imply regulation and control not only of the
Louisville effluent but also of the nonpoint sources upstream
and downstream from Louisville and of the two other point
sources on the stream. If all these measures were taken, the
stream would be greatly improved for freshwater life generally,
but I am skeptical that a game fish resource could be
establ ished in v iew of the apparent absence of game fish in the
best warmwater reaches of Coal Creek at the present time. Thus

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