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Jan 262011
 

By Tammy Gray-Searles –

Streamflows for the Little Colorado River near Woodruff are anticipated to be 75 percent of the usual amount, despite heavy precipitation in December.

According to the U.S. Department of Agriculture (USDA), the estimate is based on the “snow water equivalent,” or the amount of snowpack that will result in water runoff. A number of factors can change the amount of runoff created by snowpack, including the saturation level of the ground prior to the first snowfall and the density of the snow itself.

The runoff near Woodruff is expected to continue through May.

A report from the USDA notes that snowpack and expected runoff varies widely across the state this year, with snowpack at 86 percent of average for the Little Colorado headwaters, at 129 percent of average on the San Francisco Peaks, 97 percent of average on the Mogollon Rim and 68 percent of average on the upper Gila.

Reservoir levels are generally up, including exceptionally high levels in the Salt River system, which is at 86 percent capacity, above last year’s high and the 30-year average. Lyman Lake is currently at 18,000 acre-feet of water, compared to last year’s 10,700 acre-feet, and the 30-year average of 14,300 acre-feet. The lake can hold 30,000 acre-feet. Lake Powell is at about the same level as last year, and about 4,600 acre-feet lower than the 30-year average.

The USDA report notes that, like other basins in Northern Arizona, the Little Colorado River basin re-ceived more than 180 percent of the average precipitation amount in December. That brought the total pre-cipitation to about 120 percent of the average for the year.

Drier conditions in the months leading up to the heavy precipitation, however, affected snowpack and runoff levels. In October, the basin received about 80 percent of the average amount of precipitation, while in November it was even less, at about 70 percent of average.

A Jan. 18 short-term drought report from the Arizona Department of Water Resources indicates that drought conditions across the state have worsened in southern Arizona and improved slightly in northern Ari-zona. Much of Navajo County remains listed as abnormally dry, however, and the central part of the county is listed as still experiencing moderate drought.

According to the report, Navajo County was not one of the counties that benefited from massive storms that swept through in December.

“Two winter storms brought heavy rain and snow to central and northern Arizona, and some light showers across the southern counties. The heavy rain and snow in the north improved drought conditions in Mohave, Yavapai and western Coconino counties,” the report noted.

The short-term drought forecast also predicts that the remaining winter months will be dry.

“Any precipitation is beneficial as drier than normal conditions are forecast for the rest of the winter,” the report states.

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