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PART I <br /> Page 9 of 26 <br /> Permit No.:CO0000003 <br /> ii. If the sampling frequency is monthly or less frequent: For the period with the invalid sample results,leave the <br /> spaces on the corresponding DMR for reporting coliform results empty and attach to the DMR a letter noting that a <br /> result of TNTC was obtained for that period,and explain why another sample for that period had not been collected. <br /> If the sampling frequency is more frequent than monthly: Eliminate the result of TNTC from any further calculations,and <br /> use all the other results obtained within that month for reporting purposes. Attach a letter noting that a result of TNTC was <br /> obtained,and list all individual analytical results and corresponding sampling dates for that month. <br /> 9. "Grab" sample,is a single"dip and take"sample so as to be representative of the parameter being monitored. <br /> 10. "IC25"or"Inhibition Concentration"is a point estimate of the toxicant concentration that would cause a given percent <br /> reduction in a non-lethal biological measurement(e.g.growth or reproduction)calculated from a continuous model(i.e. <br /> interpolation method). IC25 is a point estimate of the toxic concentration that would cause a 25-percent reduction in a non- <br /> lethal biological measurement. <br /> 11. "In-situ" measurement is defined as a single reading,observation or measurement taken in the field at the point of discharge. <br /> 12. "Instantaneous" measurement is a single reading,observation,or measurement performed on site using existing monitoring <br /> facilities. <br /> 13. "LC50"or"Lethal Concentration"is the toxic or effluent concentration that would cause death in 50 percent of the test <br /> organisms over a specified period of time. <br /> 14. "Maximum Weekly Average Temperature(MWAT)"is defined in the Basic Standards and Methodologies for Surface Water <br /> 1002-31,as an implementation statistic that is calculated from field monitoring data. The MWAT is calculated as the largest <br /> mathematical mean of multiple,equally spaced,daily temperatures over a seven-day consecutive period,with a minimum of <br /> three data points spaced equally through the day. For lakes and reservoirs,the MWAT is assumed to be equivalent to the <br /> maximum WAT from at least three profiles distributed throughout the growing season(generally July-September). <br /> The MWAT is calculated by averaging all temperature data points collected during a calendar day,and then averaging the <br /> daily average temperatures for 7 consecutive days. This 7 day averaging period is a rolling average,i.e.on the 81'day,the <br /> MWAT will be the averages of the daily averages of days 2-8. The value to be reported on the DMR is the highest of all the <br /> rolling 7-day averages throughout the month. For those days that are at the end/beginning of the month,the data shall be <br /> reported for the month that contains 4 of the 7 days. <br /> Day 1: Average of all temperature data collected during the calendar day. <br /> Day 2: Average of all temperature data collected during the calendar day. <br /> Day 3: Average of all temperature data collected during the calendar day. <br /> Day 4: Average of all temperature data collected during the calendar day. <br /> Day 5: Average of all temperature data collected during the calendar day. <br /> Day 6: Average of all temperature data collected during the calendar day. <br /> Day 7: Average of all temperature data collected during the calendar day. <br /> 1"MWAT Calculation as average of previous 7 days <br /> Day 8: Average of all temperature data collected during the calendar day. <br /> 2nd MWAT Calculation as average of previous 7 days <br /> Day 9: Average of all temperature data collected during the calendar day. <br /> 3rd MWAT Calculation as average of previous 7 days <br /> 15. "NOEC"or"No-Observed-Effect-Concentration"is the highest concentration of toxicant to which organisms are exposed in <br /> a full life cycle or partial life cycle(short term)test,that causes no observable adverse effects on the test organisms(i.e.the <br /> highest concentration of toxicant in which the values for the observed responses are not statistically different from the <br /> controls). This value is used,along with other factors,to determine toxicity limits in permits. <br /> 16. "Potentially dissolved(PD)metals fraction"is defined in the Basic Standards and Methodologies for Surface Water 1002-31, <br /> as that portion of a constituent measured from the filtrate of a water and suspended sediment sample that was first treated <br /> with nitric acid to a pH of 2 or less and let stand for 8 to 96 hours prior to sample filtration using a 0.40 or 0.45-UM(micron) <br /> membrane filter. Note the"potentially dissolved" method cannot be used where nitric acid will interfere with the analytical <br /> procedure used for the constituent measured. <br />