1986-03-03_REPORT - C1981013 (4)

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flume. The hydrograph exhibits a dual peak with initial runoff from the lower drainage in the first peak and a secondary peak as runoff travels from the upper reaches of the drainage. Following a review of the data collected to date, MLR approval to decommission the station was obtained in August and monitoring ceased on August 27, 1985. Station ACF-1 is located in Apache Canyon approximately one-half mile from the Purgatoire River. drainage area of the canyon is 7566 acres with cover comprised mostly of woodland. Grazing and wildlife are the major land uses. Mining is also a land use with two shafts and a power substation located in the canyon. The spring and seep survey conducted in 1984 and 1985 (Appendix 4) monitored two seeps and one USGS spring, none of which were major contributions to stream flow. The flume station was monitored quaterly for water quality, however, no flow was encountered (Table 1-9 of Appendix 1). Flow was measured by the flume (Table 1-11 of Appendix 1). Of the 239 days the station was monitored, mean 24-hour discharge was 0.001 cfs or 0.72 ac-ft annually. The 1985 hydrograph for the station is presented in Figure 5 as 24-hour mean flow. Flow ranged from 0.001 to 9.7 cfs (Table 1-11 of Appendix 1). Figure 7 presents the typical storm water runoff hydrograph at the flume which exhibits a spike of flow for only those intense showers producing significant runoff. This single spike of short duration may be a function of land uses in the canyon. Since grazing is the major land use, vegetation in the valley bottom is sparse which increases the runoff potential. Also, there are two on- stream impoundments in the upper drainage which impound surface flow. The mine inflow study conducted during 1985 (Appendix 3) identified the two shafts as contributing approximately 10 gpm of inflow which may be coming from the alluvial system. All of these factors contribute to the low runoff observed at the flume station. Following a review of the data collected to date, MLR approval to decommission the station was obtained in August and monitoring ceased on August 27, 1985. 3.2 Ground Water Six wells in the Purgatoire River alluvium and one well in each of Apache and Ciruela Canyons were monitored monthly during 1985. Generally, wells within the Purgatoire alluvium responded directly to the level of water in the river. Wells in the two canyons responded primarily to precipitation received in the drainage. All data is contained in Tables 2-1 through 2-8 of Appendix 1. -19-