WSP06617 - Laserfiche WebLink

Home Browse Search

OlJ33!5 CHAPTER II LA1ID AND WATER RESOURCES . water period of 1931-40. The runoff for this 25-year period averages about 87 percent of that for the 42-year period, 1914 through 1955. It is there- fore considered to be a conservative basis for estimating the dependability of future flows that would be available for project use. Source of Hater SuppJ-Y The major source of water supply for the project is the Piedra River at a point 10.5 river miles upstream from Bridge Ranger Station. Water also would be obtained from Big and Little Pagosa Creeks and other minor tributary streams that could be intercepted by the inlet canal to Perry Draw Reservoir site. '!he source of supply for the hydroelectric power plan presented in this report is the Piedra River at the First Box Dam site located 8.5 river miles downstream from Bridge Ranger Station and 9.5 river miles upstreac from Piedra. The flow at that point would be partially regulated by a potential reservoir on Weroinuche Creek. Streamflow Records and Estimates . The water suppl~' a-vailable to the 0 'Neal Park project was estimated from streamflow records obtained by the Geological Survey at various gag- ing stations on Piedra f,iver, its tributaries, and adjacent streams. Data on these records are summarized in the table on the following page. The runoff record of Piedra River near Piedra was extended to cover the study period (1928-52) by correlation with Los Pinos River near Bayfield. Records of Wero1nuche Creek, Williams Creek, and Piedra River, all near Bridge Ranger Station, were in turn extended to cover the same period by correlation with Piedra River near Piedra. The mean monthly runoff of Piedra River, Big and Little Pagosa Creeks, and other tributary streams at points of diversion to the project for a 10-year base period (1951-40) Was estimated on the basis of altitude-runoff relationships. These relationships were developed from records obtained at 16 npresentative gaging stations in the eastern part of the San Juan River Basin. The mean monthly runoi'i' at each point of diversion was correlatect with the corresponding mean monthly runoff of Piedra River at Piedra to obtain the monthly runoff for the period of study. The estimated monthly flows at each point of diversion were then adjusted to total the recorded or previously estimated monthly r.moff at the nearest downstream gage. . The tables on pagES 13 and 14 show the estimated monthly runoi'i' for the period 1928 through 1952 at the points of diversion for the adopted irrigation plan, 'Ihe table on page 15 shows the corresponding runoff available for the adopted hydroelectric power plan with no allowance for future upstream development. 11