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s._:- :..- , .~ ~ .. - FLOW MEASUREMENT AND OPERATING RECORDS DATA MEMORANDUM December 20, 1988 Introduction j The purpose of this memorandum is to summarize the procedures used llnd information ~t"in~~ fr~: t~~::. ~~~~ent and. operatin~ re.cords programs unQertake. n for the San Iguel Pro e II . . The primary objectives of the flow measurement program were to develop discharge rating curves for use in the operating records program:and to assess the capacity of the Gurley Intake Ditch. The primary objective of the operating records program was to obtain more detailed information regarding operating procedures for all of the ditch companies. Each of these data collection efforts will be addressed sep~rately:' . ., Flow Measurements A flow measurement program was undertaken in the study area the week of May 9, '1988 to obtain data necessary to develop discharge rating curves for the inflow gages ai Lone Cone and Gurley Reservoirs and for the Lilylands bifurcation structure and to assess the capacity of the Gurley Intake Ditch. All flow measurement locations referenced in this memorandum are shown on Figure 1. Due to below average snowpacks in the San Juan Mountains and low spring precipitation, runoff rates during the 1988 season were low. Flow measurements were made during a period corresponding to the rising portion of the runoff hydrograph, but approximately one week before the peak occurred. The flows quickly dropped from their peak rates over a period of two days to rates similar to those measured, precluding a second round of measurements. Flows were measured following standard current metering procedures recommended by the USGS and approved by the CWCS. A Price pygmy meter was used to measure the velocity of low flows (depth < 1.0 ft or velocities < 2.5 fps) and a Price type AA current meter was used to measure the velocity of higher flows. The current meters and their calibration curves were supplied by the CWCS. All measurements were made using a wading rod. Velocities were measured at several locations across the stream at a depth of six-tenths of the flow depth to obtain an average value at each location. Flow areas for each segment were calculated using the fiow depth and the width between the mid-points of successive velocity measurements. Partial discharges were calculated for each segment by multiplying flow velocity by flow area. The partial discharges were summed over the width of the stream to obtain total flows. All current metering data and flow calculations were performed on forms I provided by the CWCS. An example of the form used can be found in Appendix A, Data Forms.