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I I I I I I I I I I I I I I I I I I I 2.3 Diversion Operations Flows in the Hartland Ditch are monitored at a gaging station located approximately 245 feet downstream of the spill channel. The gaging station consists of a concrete flume and staff gage. A rating table of stage versus flow was provided to Tetra Tech, Inc. by the State Engineers Office and is found in Appendix F. Gage records for the Hartland Ditch are available from 1970 to present. Based on conversations with HIC, the spill channel flows, upstream of the gage, are typically 10 cfs (HIC 2000). Flows through the gage average 40 cfs with peak days of 60 to 70 cfs. The highest peak on record is 90 cfs, diverted on October 31, 1979. Since the gage is downstream of the spill channel, the flows diverted out of the Gunnison River at the headgate are typically 10 cfs higher than those recorded at the gage. The period of operation of the diversion is typically from early April through October, although the records indicate that in some years the diversion has been operated all year long (CDSS 2000). The diversion supplies water for irrigation of approximately 2385 acres of crops, including alfalfa, corn grain, grass pasture and spring grain. The diversion also supplies water for stock watering (CDSS 2000). HIC indicated that there has been one instance, approximately ten years ago, that they were unable to divert sufficient flows due to low flow conditions in the Gunnison. This was resolved by minor earthwork in the main river. Otherwise, in general, the ditch headgates are used to restrict the inflow to the rates noted above (HIC 2000). HIC has also indicated that under current operation conditions, fish (native and non- native) and trash are entrained in the Hartland Ditch. Trash, especially large debris, is often removed by the ditch rider near the headgate area. Fish, however are typically removed manually near and around the individual points of diversion and disposed of (HIC 2000). 4