Sediment Approach

•  Toxics have varying solubility in water which affects their movement.

•   Water soluble toxics (such as, diazinon, atrazine, & some heavy metals) can be transported in surface water or ground water

•  Less soluble toxics can bind to soil particles (such as, Pyrethroids, DDT & PCBs )

•  Erosion and transport of soil to waterbodies can carry soil-bound toxic chemicals

•  But, certain types and delivery of sediment is important for proper stream function

Episodic Sediment Delivery: Benefits

•  Sediment delivery to bodies of water is a key part of natural ecosystems

•   Slides on forested lands deliver key components to aquatic ecosystems

•   Large woody debris (LWD)

•   Gravel and cobbles

•   Slides from mature or burned forests are rare occurrences

•   Once every ~300 years in larger streams, less often in smaller streams

•   Short-term negative impacts with long-term gains in ecosystem productivity

Chronic Sources of Fine Sediment: Potentially Harmful

•  Chronic sources like road runoff create constant stress on aquatic ecosystems

•   These sources lack the legacy that creates long-term benefits (no LWD or gravel)

Sediment Delivery and Toxics

•  Nonpoint Sources of fine sediment and toxics:

•   Roads (Heavy metals, PAHs, other petroleum products)

•   Urban Stormwater

•   Agricultural lands (Pesticides, petroleum products)

•   Private forest operations (Pesticides, road runoff)