 Nearly all municipal wastewater (98 percent) and 90 percent of industrial wastewater is discharged to rivers and creeks without any treatment.The highest priority for pollution abatement is estimated to be in the basins of the Río Acelhuate and Río Sucio, an area that supplies a third of the water supply of the Metropolitan area of San Salvador.Over the past 20 years the yield of a sample of springs declined by 30 percent due to deforestation.