Peace and Myakka River Water Quality Summary 2002 - Southwest ...

2.2 RAINFALL AND STREAMFLOWThe amount of rain that falls on a watershed in a given year can have important effectson streamflow and water quality. In the Peace and Myakka River watersheds, annualrainfall and streamflow levels varied dramatically during water years 1998-2001. Totalannual rainfall and average annual streamflow at three monitoring stations are shown inFig. 2.A strong El Niño event occurred during the 1998 water year, and total annual rainfall inthat year was substantially higher than the long-term (1950–2001) mean value at eachstation. Annual mean streamflows were also quite high during the 1998 water year,exceeding 200% of the long-term (1950-2001) values at each station (Fig. 2).Rainfall returned to near-average or below-average levels in water years 1999-2001,and annual mean streamflow declined in response to the lower rainfall (Fig. 2). Annualstreamflow at the Peace River-Bartow station remained far below its long-term meanduring water years 1999-2001, falling to less than 25% of its long-term value in 2001.Annual flows at the other stations — the Peace River at Arcadia and Myakka River nearSarasota — fell to between 30% and 60% of their long-term means during water year2000, but rebounded in 2001 to levels near or above the long-term means.8