Trapezoidal drains are often a source of water quality problems in headwater areas. Bank erosion can be common because the bank heights greatly exceed the bankfull depth. Even where the banks are stable, the channel is typically over-wide which promotes sediment deposition, increases temperatures, and causes turbidity during runoff events. Two-stage and multi-stage design options are effective ways to provide conveyance while improving water quality. Presented by Rob Myllyoja.