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November 28, 1997 <br />Mr. John Hazdaway <br />page 3 <br />But, until the results of the ammonia study are available and the model is actually run, it <br />may be difficult to accurately assess this potential. <br />Examination of the data we already have -for AG2.0 and 0003, shows a median pH of <br />7.2 and a median temperature of 12.7°C at point AG2.0; and a median pH of 8.0 and a <br />median temperature of 7.3 °C at point 0003 for the period following June, 1995. <br />Neglecting diurnal or seasonal variation, these factors translate to an allowable instream <br />total ammonia concentration of 4.2 mg/I in Cripple Creek, and 6.5 mg/1 for Arequa <br />Gulch. <br />This difference does not appeaz great enough to overcome the effect of additional <br />dilution. However, it should again be noted that the influence of diurnal and seasonal <br />variation has been neglected, as well as any upstream total ammonia load in Cripple <br />Creek, and the instream decay of ammonia in Arequa Gulch. Also, the data for 0003 is <br />fairly limited. <br />As a result of the above considerations, it may be prudent for CC&V to periodically <br />examine pH, temperature and ammonia levels in Cripple Creek and compare them to the <br />readings for Arequa Gulch. Hopefully, it will be possible to make some reasonable <br />assessments as to the need for extending ammonia limitation development into Cripple <br />Creek. <br />If there is an indication that such extension is necessary, it would probably make sense to <br />treat Arequa Gulch as a discharge going into Cripple Creek, taking pH and temperature <br />readings in Arequa Gulch at its lowest point, and in Cripple Creek just above the <br />confluence with Arequa Gulch. It might also be necessary to assess whether or not the <br />diurnal variability in the two streams was different. Of course, if such additional analyses <br />are required, we should probably meet to discuss the details of additional data collection, <br />and how atwo-stage TMDL for ammonia and the associated CAM modeling required for <br />such a TMDL would be performed. <br />Thank you for your patience and continued cooperation. <br />