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I I I I I I i i I I I I I I I I I I I MUSICK, WILLIAMSON, SCHWARTZ, LEAVENWORTH & COPE, P. C. 001729 Water Quality Control Commission June 27, 1980 Page Five mittent stream. The limited flow in Coal Creek will obviously affect the variety of life forms which can be present. It should be noted that irrigation diversions are the main source of the intermittent flow. Thus, any attempt to improve this flow may prove to be rather difficult. In addition, Dr. Lewis discusses the existing streambed characteristics of Coal Creek, namely, the sandy bottom and irri- gation ditch character of the stream. Such characteristics obviously represent a Class 2 fishery as opposed to a Class 1. III. Specific Ammonia Limitation for Coal Creek Presently, the Water Quality Control Division has proposed a 0.06 mg/l unionized ammonia level for Coal Creek. Louisville believes that as a Class 2-Warm Water Aquatic Life stream, the appropriate number to be placed on this stretch of Coal Creek is a number reflecting the present background ammonia levels. As the WQCD presently utilizes the "Basic Standards" to insert the 0.06 mg/l standard into NPDES permits, it is important to develop a specific ammonia number. The report submitted by Dr. Lewis indicates that instream standards for Coal Creek at the present time exceed the proposed 0.06 mg/l level even above the Louisville sewage treatment plant discharge. It should be noted there are no point source discharges above the Louisville discharge point. Thus, other factors are affecting the level of ammonia in the stream. One could only speculate to the extent that the higher ammonia levels are due to agricultural runoff and other non-point sources. Dr. Lewis' report also indicates that the ammonia concen- tration drops to a level of 0.03 mg/l prior to the confluence of Coal Creek with Boulder Creek. Thus, the natural biological processes are reducing the ammonia level, despite the existence of three sewage treatment plant discharges in this stretch of the stream (Louisville, Lafayette, and Erie). In addition, Dr. Lewis' report indicates that there is li ttle or no improvement in the fishery from the confluence to just below the Louisville discharge. (Louisville does not contend that the fishery below their discharge is the same as that above the discharge. Although similar in the nature of fish, there were virtually no fish below the Louisville discharge, but there were some fish above the discharge. )