OCR Text |
Show i Colorado River Runoff Afoiv 726 Percent Above Normal The April through July runoff run-off from the Colorado River watershed above Lake Powell Is expected to reach 9.8 million mil-lion acre-feet, or 126 per cent of the longtime average, the Bureau of Reclamation announced today. The forecast Is based on the water content on April 1 of sixty-four snow courses within the watershed area. It presumes normal precipitation precipita-tion for the remainder of the runoff season. Lake Powell will rise from its present elevation, 3,646 feet, to about 3,675 feet above mean sea level. Releases from Glen Canyon Dam from April to September 1975 will be 5.6 million acre-feet with a water year total for 1975 of 9.3 million acre-feet. Lake Powell should remain above elevation, 3670 feet through the summer months and then drop slowly during the fall and winter. The lake elevation eleva-tion prior to the 1976 spring runoff should be about elevation eleva-tion 3,665 feet and have an ac tive content of 19.9 million acre-feet. The waters of Lake Powell are expected to reach a depth of 21 feet In the channel beneath be-neath Rainbow Bridge by the end of summer 1975. The National Park Service says boaters wishing to visit Rainbow Bridge may moor -their boats at a courtesy dock near the boundary of the National Na-tional Monument and then complete the visit by foot. To preserve the serenity of the natural environment In the vicinity of the Bridge, boats will be allowed to proceed no farther up the channel than the courtesy dock, even though the water will rise to higher elevations this season. About 1.3 million acre-feet of runoff should originate on the Green River watershed above Flaming Gorge Dam, or 116 per cent of normal. Of this amount, 175,000 acre-feet acre-feet will be stored In Fonten-elle Fonten-elle Reservoir. If the forecast fore-cast above Flaming Gorge Dam Is realized, the reservoir reser-voir should fill to elevation - 6,040 feet above mean sea level, le-vel, which Is Its maximum storage level, with a content of 3.75 MAF by August 1975. Blue Mesa Reservoir Is expected to receive about 980,000 acre-feet of Inflow, or 124 per cent of the long time average. The lake would therefore fill to elevation 7,-519 7,-519 above m.s.l. with a usable content of 830,000 acre-feet. Morrow Point Reservoir, immediately im-mediately downstream from Blue Mesa Dam, should remain re-main near full at 117,000. acre-feet throughout the year. On the San Juan River, Navajo Na-vajo Lake should receive a runoff equal to 130 per cent of normal. Releases from the lake are being Increased to 2,000 cubic feet per second on April 15. With the 900,000 acre-foot mean forecast and the 2,000 cf.s. release, the lake level should rise to elevation ele-vation 6,067 feet above mean sea level which will be within 18 vertical feet of being full. Lake Mead's present ele vat Ion Is 1,177 feet above m.sj. or about 3 feet higher i than a year ago. The reser- I voir is now 44 feet below the top of the raised spillway gates at Hoover Dam . At present pre-sent It contains 19.7 million acre-feet of available storage or 75 per cent of Its capacity. Based on the present forecast, Lake Mead Is expected to decline de-cline to about elevation 1,173 feet above m.s.l. by the end of May and then rise to about elevation 1,181 feet above m.s.l. by the end of Septa m-ber. |