Overview of drought and hydrologic conditions in the United States and southern Canada, water years 1986-90

This report describes the drought and hydrologic conditions in the United States and southern Canada during the 1986-90 water years. This drought, which spread from the Eastern United States, where it was referred to as 'the drought of the century,' through the Midwest to the West Coast, brought to mind the Dust Bowl era of the 1930's. However, generally localized floods were numerous, but only one hurricane (Hugo) was of any consequence to the United States, Puerto Rico, and the Virgin Islands during a coincident period of anomalously low hurricane activity. The drought began in early 1984 as an 'agricultural drought,' which is a precipitation deficiency that results in a lack of soil moisture that is detrimental to agricultural production. This condition did not affect streamflow until about March or April 1986. A 'hydrological drought,' which is far more serious and widespread than an agricultural drought, was apparent from the low streamflow conditions that occurred after April 1986. To illustrate the changing nature of the drought, maps and synopses of monthly hydrologic conditions for the water years 1986-90 are presented.