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• 2001 Annual Hydrologic Report Page 4 wells since monitoring began in 1984. Table G01-1 was prepared to show average water levels in the spring and fall to correspond to high and low water levels in the adjacent creeks respectively. Piezometers CRDA-01 thru 06 at the Cameo Refuse Disposal Areas (CRDA) No. i and No.2 continued to be monitored quarterly. Data page GC-10 includes measurements for this Year. A graphical representation of the water level elevations in CRDA-01 is shown on Diagram G01-4. Water levels increased slightly this Year. Most of the original CRDA-# piezometers and the PZ-# piezometers showed only slight variation during the Year. The results of water level measurements at the unit train loadout this Year are listed on Data page GB-2. Diagrams G01-5 and 6 are graphical representations of water level elevations in these piezometers. Table G01-2 was prepared to show statistics on these water levels corresponding to high and low flows in the adjacent river. Quality information is presented on page GD-13. A former mine dewatering hole (N-1) located at the North Decline area of the mine is • used to monitor the water level in the abandoned portions of the Roadside South Portal In order to characterize the Rollins Sandstone two surface and two underground wells were installed during June 1997. The surface wells were installed at the north decline and the unit train loadout. The underground wells were installed in the North and South Portals. Depth to water ranged from 56.5 feet below grade in the North Decline well to artesian in the North Portal well. Monitoring of these wells will continue in accordance with permit requirements. Rollins-1 and 4 located underground in the North and South Portals respectively were sealed during the year. Depth to water data is presented on data page GE-1. Quality information is presented on pages GE-10 and GE-11. The water level must be maintained between elevation 4755 and 4762 to assure the siphon continues to function. This 7-foot elevation range equates to about 2.3 million gallons per foot or about 16.1 million gallons (ref. Table M01-1). The discharge from the siphon is increased or decreased, by adjusting a valve, depending on water level measurements in well N-1. Changes in the elevation of the Northwest Intake Pool are gradual because each foot of increase or decrease represents 2.3 million gallons, The results of monitoring N-1 are presented in Table M01-2.