Suspended sediments discharged from three rivers into Mayaguez Bay, Puerto Rico are estimated. Annual growth rates as determined from coral banding decreased significantly (r = 0.69) with increased sediment loading to the bay (tons/year). Evidence from remote sensing and hydrologic modeling suggests that sediment reaches the reef only during episodic, high-discharge events. During low to moderate discharge, sediments, both suspended within the river plume and resuspended sediments, are restricted to the near-shore regions by the prevailing circulation. Hence, a direct relationship between river runoff and coral growth rates was established in this study.