1988-04-11_PERMIT FILE - C1981008A

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Site SW-N3 is located on Tuttle Draw downstream of mining as shown on Exhibit 7-1. Discharge measurements have routinely been collected from this . site since April , 1980. Flow at SW-N3 is artifically controlled for the most part of the year from irrigation return flow from the lower Second Park lateral irrigation ditch. During the irrigation season, a significant portion of the flow at SW-N3 is contributed by NPDES 001 pond located just upstream of SW-N3 on the West Return Ditch (see Exhibit 7-1). Measured discharge at Site SW-N3 range from .019 cfs up to 9.35 cfs (see Table 7-40). During the irrigation season, the means of measured discharge range between about .5 cfs and 4.67 cfs. Measured high flows for this period range between .665 (April) and 9.35 cfs (September). During the non-irrigation season, discharge measurements ranged between .019 and 2.09 cfs. It should be stressed that discharge measurements at surface water monitoring sites at both the Nucla Mine and Nucla East mining area were not necessarily collected on the same day. Measured high and low flows previously and subsequently discussed for up- and downstream sites established in one drainage may not reflect "same-day" measurements. West Return Ditch. The West Return Ditch is a tributary to Tuttle Draw and is commonly used for conveying irrigation tail water to Tuttle Draw (see Exhibit 7-1). Flow in this ditch generally recedes to zero in the lower reaches after the end of the irrigation season. Site SW-N7 is located above Site SW-N6, just above the northern permit boundary for the Nucla Mine. SW-N6 is established about k mile below SW-N7 on the West Return Ditch. Measured discharge at SW-N6 has been routinely collected since August of 1980. Table 7-41 presents means and ranges of discharge measurements collected at surface water monitoring Sites SW-N6 and SW-N7. Flow generally recedes to zero during the non-irrigation season. Of the 44 monitoring visits made at SW-N6 for the period of record during the non-irrigation period (November through April), flow larger than one-hundreth of a cfs have been measured only six times. For the irrigation season, flows at SW-N6 has been commonly observed, ranging from zero up to a high of 1.34 cfs. SW-N7 was established as a surface water monitoring site in March of 1987. This site was established by Peabody for obtaining baseline data in the case that mining in the "triangle area" might begin in early 1987. The triangle area is a small strip of land located below existing Site SW-N7, bordered by the County Road 2650 on the west and the county landfill on the east (see Exhibit 12-1, Tab 12). Although plans for mining the 7-116 Revised 04/11/88