Although recent field studies have shown that concentrations of herbicides in streams are low following applications made when modern best management practices (BMPs), some data gaps have been identified. In particular, data showing duration of elevated herbicide concentrations immediately preceding and following storm events are lacking.
In addition, in previous studies, detection limits for some herbicides were above levels that are associated with effects on some non-target aquatic plants, making assessment of potential risks to those plants difficult. This study is taking advantage of currently instrumented watersheds on managed forestlands. Autosamplers and grab samples are being used to collect water samples prior to application, immediately post-application, and during and following the first two post-treatment rain events to quantify herbicide concentrations.
The resulting dataset will provide quantitative information on the effectiveness of BMPs.