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1 1 1 1 1 1 1 1 1 Annual Eye'-ology Report April 22, 1988 Page 22 spring runoff. Dewatering procedures take usually less than one day with the exception of MB-5 which is responsive to a high spring groundwater table and sometimes has to be dewatered more often. Ponds t~ffi-3 and MB-4 have not discharged during 1987 and records indicate they have not discharged since they were constructed. MB-4 sometimes catches hydraulic oil spills from the Unit Train Loadout and is pumped by a licensed contract hauler or the WDOC vacuum truck which deposits the oil in the shop waste oil tank which is in turn pumped by a licensed waste oil recycling firm. This is a standazd procedure. f Flowmeters have been installed on all discharge points from sediment ponds which dischazge intermittently to continuously record flows. The Quarterly Hydrology Reports contain information on flows, sampling points, and quality of water discharge from the mine site sediment ponds in 1986. All water discharged was in compliance with NPDFS permit effluent limitations. During spring runoff conditions as well as some precipitation events quality of water in the North Fork of the Gunnison is much worse than the quality of discharges from F1FX]C sediment ponds and well outside NPDFS effluent limitations. During winter baseflow and summer conditions water quality in the North Fork is better and is within NPDFS effluent limitations, however, this is the time of year when WECC's ponds are rarely discharged. Flow amounts from WECC sediment ponds are low in comparison to the North Fork of the Gunnison flows. Ewen during low flow conditions on the North Fork P7EgC dischazges represent an imperceptible difference in stream quality. It is apparent from the analyses that sediment pond discharges have had no adverse impact on the North Fork of the Gunnison River. The quality of discharges usually exceeds the quality of the North fork; and discharge flows are so small that incremental changes in concentrations in the North Fork are imperceptible. Discharges of surface runoff is 1987 are expected to be similaz to 1986.