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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001738

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indicates reduction of ammonia levels by biological processes.
Reduction downstream might be less marked in the winter, but we
do not know this.

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Although one of the documents supplied to me (Weuthele
1976) indicated that Coal Creek degrades Boulder Creek with
respect to ammonia, I do not find this well supported by the
data for summer of 1980, as the unionized ammonia levels on
the two sampling occasions were as low or lower than expected
in Boulder Creek from the STORET data. Weuthele's data were
taken in winter, however, when the situation may have been
different.

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Conclusions Concerning the Aquatic Fauna of Coal Creek.
Since the ammmonia standard is based almost exclusively on
ammonia tolerance of fishes, and since no information seems to
exist on tIle invertebrates of Coal Creek, the conclusions here
apply to the fish fauna only. It is generally believed that
the unionized ammonia of running waters is more dangerous to
fish than to any other component of the fauna (EIFAC 1973),
although this has not been studied very carefully.

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The informat ion I have on fish is from three sources:
(1) information from the U.S, Water and Power Resources
Service gathered in fall of 1979 at various locations along
Coal Creek, (2) State of Colorado, Stream Classification
Survey Forms for Boulder Creek and Coal Creek, and (3)
electroshocking on 11 June 1980 above and below the Louisville
discharge for the specific purpose of obtaining current
information on the fish composition in Coal Creek around
Louisville (see attachment 2). Wherever fish are found in Coal
Creek or in Boulder Creek near its confluence with Coal Creek,
the fish fauna is typically dominated by three species: (1)
the creek chub (Semotilus atromaculatus), (2) the fathead
minnow (Pimephales promelas), and (3) the stoneroller
(Campostoma anomalum). In selected locations the longnose dace
(Rhinichthys cataractae) and the white sucker (Catostomus
commersoni) appear in reasonably large numbers. The green
sunfish (Lepomis cyanellus) appears in very limited numbers, as
do a few other species, Boulder Creek beyond 75th Street
and Coal Creek throughout most of its length are too warm for
trout except perhaps if the stream is impounded.

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Although a rather unified picture of species composition
is given by the three different fish collections, the
collections, and particularly most recent sample on Coal
Creek, SllOW some radical difference between sites in the
abundance of fish. Beginning at a point several kilometers
above the Louisville discharge (see attachment 2), fish are
abundant and show evidence of being healthy and in good

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