SALEM, Ore. (AP) – Environmental regulators say pesticide levels in some Oregon waterways have dropped to fractions of former concentrations due to voluntary changes by farmers.

The Capital Press reported Wednesday that the state Department of Environmental Quality found that growers who altered spray regimens helped achieve the water quality improvements.

Officials say about 50% of waterway sites tested under an interagency “pesticide stewardship partnership” program showed progress in pesticide detections and concentrations.

Areas with reductions included the Walla Walla watershed and Waco basin.

The tests compared results between 2015 and 2017 to the previous two years.

Officials say about 27% of tested sites showed declines in water quality from pesticides, while 23% showed no change.

Officials say the monitoring targets streams where pesticides have been detected, while waterways without occurrences were dropped.

Information from: Capital Press,