Total precipitation during the 1988 water year was about 86 percent of normal in western Washington and about 83 percent of normal in eastern Washington. The total precipitation for the water year ranged between about 75 and 92 percent of normal throughout the State. Precipitation during October was the farthest below normal for a month when the monthly total was less than 10 percent of normal in both western Washington and eastern Washington. Monthly precipitation was the farthest above normal during May in western Washington, and during December in eastern Washington, when monthly totals exceeded 185 and 150 percent of normal, respectively.

Rainfall in western Washington was less than 75 percent of normal during the months of October, November, January, February, and August. It was near normal during December, June, July, and September, and was more than 125 percent of normal during March, April, and May.

In eastern Washington, precipitation was less than 75 percent of normal during the months of October, November, January, February, July, and August. It was near normal during March, May, and September, and was more than 125 percent of normal during December, April, and June.

The annual mean runoff in both western and eastern Washington during the 1988 water year was below normal.

The most significant floodflows of the 1988 water year occurred during December 9, 10 in western Washington streams. Peak flows at gaging stations had recurrence intervals generally ranging from two to five years. (A peak flow that has a recurrence interval of five years can be expected to be exceeded once in five years on the average.) The annual peak flows at most gaging stations in eastern Washington had recurrence intervals of one to two years.

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