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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OD1737

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Boulder Creek; no State informat ion is available for points on
Coal Creek above Louisville except for one sampling for which
data could not be located. Louisville has provided samples on
2 different dates for the effluent and for one point on Coal
Creek above Louisville and several points below (Attachment 1).

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One final deficiency is the apparent unavailability of
streamflow records for Coal Creek both above and below the City
of Louisville. This information is important for stream
class i f icat ion and as a bas is for judgment of the impac t of the
Louisville discharge on Coal Creek. Similarly, no objective
information is available concerning streambed characteristics,
which are central to the State classification system. I am
offering a little streambed information derived from the
electroshocking on 11 June (Attachment 2).

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The following conclusions must be somewhat tentative in
view of the deficiencies in existing information. These
deficiencies could and should be corrected before long-term
decisions are made concernlng the future status of Coal Creek
below Louisville.

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Conclusions Concerning the Ammonia Levels in Coal Creek.
Although the information on ammonia levels above Louisville is
scanty, the available information definitely indicates that the
ammonia levels above Louisville do on at least some occasions
substantially exceed the proposed .06 mg/l standard for
unionized ammonia. Of the two readings we have above the
Louisville effluent, one is near (0.054 mg/l) and the other
almost double (0.11) the .06 level. Since there are no point
sources above Louisville, it would appear that nonpoint sources
are causing the water reaching the louisville discharge point
to exceed the proposed .06 mg/l standard. It should be noted
that these samples, although above the Louisville discharge,
were not in the uppermost reaches of the stream. No samples
are available from the uppermost reaches.

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It is clear from the existing data and is a matter of
record that the effluent from the Louisville treatment plant
does exceed the .06 mg/l proposed standard. The existing
information indicates that the effluent is of the order of 2-5
times higher in unionized ammonia than the proposed 0.06 mg/l
standard (see attachment 1).

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The two available sample sets show surprisingly rapid
decline of ammonia levels below Louisville, despite the
existence of two sewage treatment plants that also are not
treating for ammonia. On both of the 1980 summer sampling
occasions, the arrnnonia levels had fa(len below the 0.03 mg/l
level by the time the water reached Boulder Creek. This

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