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but heavily cultivated and developed watershed area in the upper portion of Calamity Draw, little <br />supplemental flow from precipitation and snowmelt runoff occurs <br />Surface water monitoring Site SW-N101 was established in Calamity Draw above the eastern <br />boundary of the New Horizon 2 Mining Area (see Map 2.04.7-1 ). SW-N101 was monitored for flow <br />since July of 1986, as part of the baseline monitoring program established for this mining area. <br />Peabody Appendix 7-5 contains instantaneous discharge measurement collected at this site since <br />1986. During the irrigation season, measured discharge ranged from .605 in April up to 13,4 cfs <br />during Jufy. Measured flows during the non-irrigation season ranged between 1.04 and 2.06 cfs. <br />Interestingly, the short record of discharge measurements may suggest that shallow ground water <br />discharge into Calamity from irrigated lands provided a fairly continuous source of baseflow to <br />Calamity Draw during the non-irrigation season. Monitoring of this site was discontinued after the <br />New Horizon 2 Mine became operational. It was replaced by two surface monitoring stations SW- <br />N108 and SW-N109. The upstream station, SW-N108 is located just west of Lincoln Street as it <br />flows from under the road. This station defines water quality and quantity before it enters the area <br />potentially influenced by the mine. SW-N109 is located on Calamity Draw west of the mine permit <br />boundary but east of the Nucla waste water lagoons. This station will define the water quality and <br />quantity as it leaves the site but before it is influenced by the waste water lagoons. <br />SW-N102 was established on a small tributary of Calamity Draw that returns irrigation tail waters <br />from irrigated fields to the main channel of Calamity Draw. Flow at this site was almost entirely <br />influenced by irrigation, although the limited discharge measurements made since July of 1986 <br />indicated that residual discharge of shallow ground water from the irrigated fields above the site <br />contributed some flow up through even January. During the irrigation period, measured flow <br />ranged from .088 cfs (October) to 2.18 cfs (August). During periods of no irrigation, flow <br />observations made at SW-N2 ranged from zero (February, March and early April) up to .031 cfs <br />(January). This site is now being monitored as NPDES OutfaA No. 007. <br />SW-N107 was located about a mile and a half below SW-N101 on Calamity Draw. Flow <br />measurements were only periodically collected at this site since July of 1986. A crest-stage gage <br />has been installed at this site for the purpose of recording high water marks of large runoff events <br />(rainfall or spring snowmelt runoff). These high water marks were used to determine the peak <br />discharge of large runoff events using indirect discharge measurement techniques. Since <br />(Revised 25 Jul 2002) 2.04.7-27 <br />