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Appendix B <br />Page 51 of 56 <br />Permit No.: C00032115 <br />11. "Discharge" - when used without qualification, means the "discharge of a pollutant." See 5 CCR 1002-61.2(22). <br />12. "Discharge of a pollutant" - the introduction or addition of a pollutant into state waters. See 25-8-103(3) C.R.S. <br />13. "Dissolved (D) metals fraction" is defined in the Basic Standards and Methodologies for Surface Water 1002-31, as <br />that portion of a water and suspended sediment sample which passed through a 0.40 or 0.45 UM (micron) <br />membrane filter. Determinations of "dissolved" constituents are made using the filtrate. This may include some <br />very small (colloidal) suspended particles which passed through the membrane filter as well as the amount of <br />substance present in true chemical solution. <br />14. "Good Engineering, Hydrologic and Pollution Control Practices' - methods, procedures, and practices that a) are <br />based on basic scientific fact(s); b) reflect best industry practices and standards; c) are appropriate for the <br />conditions and pollutant sources; and d) provide appropriate solutions to meet the associated permit requirements, <br />including all effluent limitations. <br />15. "Grab" sample, is a single "dip and take" sample so as to be representative of the parameter being monitored. <br />16. "IC25" or "Inhibition Concentration" is a point estimate of the toxicant concentration that would cause a given <br />percent reduction in a non -lethal biological measurement (e.g. growth or reproduction) calculated from a <br />continuous model (i.e. interpolation method). IC25 is a point estimate of the toxic concentration that would cause <br />a 25 -percent reduction in a non -lethal biological measurement. <br />17. "Industrial Activity" - the 10 categories of industrial activities included in the definition of "stormwater discharges <br />associated with industrial activity' as defined in 5 CCR 1002-61.3(2). <br />18. "Industrial Stormwater" - stormwater runoff from industrial activity. <br />19. "In-situ" measurement is defined as a single reading, observation or measurement taken in the field at the point of <br />discharge. <br />20. "Instantaneous" measurement is a single reading, observation, or measurement performed on site using existing <br />monitoring facilities. <br />21. "LC50" or "Lethal Concentration" is the toxic or effluent concentration that would cause death in 50 percent of the <br />test organisms over a specified period of time. <br />22. "Maximum Weekly Average Temperature (MWAT)" is defined in the Basic Standards and Methodologies for Surface <br />Water 1002-31, as an implementation statistic that is calculated from field monitoring data. The MWAT is <br />calculated as the largest mathematical mean of multiple, equally spaced, daily temperatures over a seven-day <br />consecutive period, with a minimum of three data points spaced equally through the day. For lakes and reservoirs, <br />the MWAT is assumed to be equivalent to the maximum WAT from at least three profiles distributed throughout the <br />growing season (generally July -September). <br />The MWAT is calculated by averaging all temperature data points collected during a calendar day, and then <br />averaging the daily average temperatures for 7 consecutive days. This 7 day averaging period is a rolling average, <br />i.e. on the 8th day, the MWAT will be the averages of the daily averages of days 2-8. The value to be reported on <br />the DMR is the highest of all the rolling 7 -day averages throughout the month. For those days that are at the <br />end/beginning of the month, the data shall be 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 It 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 />