Laserfiche WebLink
<br />~ <br />c <br />c.~ <br />- <br />c <br />c <br /> <br />Surface Water Supply <br /> <br />18. The drainage area of the Little Colorado River system above <br />Penzance Dam occupies over 12,000 square miles. The northern and <br />eastern tributaries consisting of Puerco River, Zuni River, Carrizo <br />Wash, and Leroux Wash, flow intermittently, mainly as a result of <br />rains. Their streambeds throughout most of their length permit <br />heavy channel losses . Rainstorms, particularly during late summer <br />and early fall, cause heavy and often flashy flows. At other times <br />their streambeds may be completely dry and they contribute nothing <br />to the streamflow of the river. The upper reaches of the main stem <br />of the river and Silver Creek, its principal southern tributary above <br />the project area, are perennial streams as both rise in well main- <br />tained, forested mountain areas. The dependable flow of the upper <br />reaches of the Little Colorado River" however, is stored or diverted <br />for irrigation use in the upper areas. Although much of the water of <br />Silver Creek and its chief tributary, Showlow Creek, is stored and <br />diverted for irrigation, it contributes some flow to the main stem <br />most of the time. The net result of the combined flow characteristics <br />of the various tributaries is an extremely fluctuating discharge in the <br />Little Colorado River at Penzance. <br /> <br />19. No streamflow records are available for the Little Colorado <br />River at Penzance Dam. Discharge at this point was estimated from <br />daily streamflow records of the Geological Survey for the Little <br />Colorado River near Woodruff, Arizona, which is about 15 miles <br />above Penzance, and for the Puerco River near Adamana, Arizona, <br />about 27 miles above Penzance, adjusted for estimated downstream <br />channel losses. The estimated annual discharges for the period 1940 <br />through 1947 varied from about 20,000 acre-feet in 1944 to 280,000 <br />acre-feet in 1941, a year in which 40 percent of the total discharge <br />for the entire period occurred. The average annual flow for the <br />eight years was about 86,000 acre-feet while for the seven years <br />excluding 1941 it was only 51,000 acre-feet. Monthly streamflow <br />during the period also fluctuated widely, from nothing in some months <br />to a discharge of 65,000 acre-feet in August 1947. Because of the <br />erratic streamflow characteristics of the Little Colorado River, <br />there is no very definite or fixed pattern of discharge. In general, <br />however, the river recedes after the spring runoff, the flows becoming <br />extremely low or nonexistent during April through June, then increas- <br />ing again to the high flows resulting from summer rainstorms usually <br />beginning in July, <br /> <br />.,,: <br /> <br />20. The water supply for the Joseph City area is obtained by <br />diversion of the unregulated river flow which is supplemented by about <br />2.3 second-feet of flow from artesian wells. The estimated average <br />water requirement is only 3,070 acre-feet annually. There is usually <br />an ample supply prior to and during the early part of the irrigation <br />season and in the latter part of the season. During the critical period <br />April through June the streamflow is usually inadequate to meet <br />irrigation requirements, with no flow at all in June during 6 of the <br />8 years of the period studied. <br /> <br />~ <br /> <br />" <br />;:. <br /> <br />7 <br />