The Lower Bear Tributary Water Quality Improvements project included constructing a stormwater treatment train in a fully developed urbanized setting. BHI developed an innovative stormwater treatment train concept that progressively captures finer material moving downstream. As the stormwater runoff moves through this arroyo, it passes through a series of BMPs, referred to as Treatment Cars, each designed to remove additional pollutants from the stormwater to help protect the water quality of the Rio Grande and the aquifer. The treatment train addresses both stormwater quantity as well as quality. Lessons learned from this treatment train pilot project through performance monitoring will be formulated into a template for other projects in the region.