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Mr. Jack Haines February 13, 1976 Page Five Gravel mining adjacent to the channel can have an adverse effect on potential flooding. It is normal for the river channel to shift and meander during periods of high flow. Removal of material may leave an adverse effect by causing the relocation of ti,e river to an area where it would normally not have shifted. Aerial photographs of the 1973 flooding show nearly the entire area of the low land pasture are to be within the 100 year floodplain. [ligher ground immediately north of the mining site, however, should prevent a main relocation of the river channel to the east. Should there be a relocation of the river channel the operators may have to put the channel back in its original place. It is expected that the area ~ncavated during mining will eventually be filled again after a major Llood. WATER nUALITY f~ater quality in the South Platte River near the site is generally poor. This reach of the river }ras been classified b•.+ the State as C a:rd Dl indicating the water is suitable for irrigation and industrial uses. Tests conducted by the Colorado Department o`, Health in January through August of 1975 at Henderson indicate that average temperature, pH and dissolved oxygen levels are generally conducive to certain species of fish life. Dissolved nutrient. levels were quite high, however, indicating a condition detrimental to fish but beneficial to the use of the water for irrigation. The many municipal waste water and industrial discharges into the river have an adverse impact on the quality of water in this reach of the river. Three major irrigation systems in this reach hrive combined average annual diversions from the river of approximately 40,000 acre feet. Return flows of water following irrigation also contribute to the poor quality of water in this reach. It is nc.t anticipated that the mining operations will dis- charge water directly to the South Platte River. Any water pumped from excavations at the site would be at least equal in quality to that of the river at the present time. Upon completion of the reclamation plan, water in excavated areas would be part of the regional ground water table and would reach the river only after flowing through sands and gravels.