Senior Stormwater Systems Scientist Craftwater Engineering, Inc.
Some of the most daunting problems facing a watershed manager focused on providing protections for receiving waters from stormwater runoff are to determine what types of stormwater control measures (SCMs) are needed, how many will provide the watershed with adequate protections from stormwater runoff, and where they should go to provide the most impactful capture and treatment. While the design of individual SCMs to treat runoff from a single drainage area is well understood, the coordination of multiple SCMs across a watershed to impart positive changes in receiving waters is still a developing science. Effective planning and implementation of SCMs at this scale is subject to a complex set of constraints and conditions that must all be addressed under a common goal or protective measure for the receiving waters being managed. This requires developing a foundational understanding of the watershed’s SCM needs on a spatial scale and rectifying this with a watershed’s limitations on feasibility or cost-effectiveness in regards to SCM implementation. This presentation will focus on some of the most important factors influencing coordinated watershed-wide stormwater management planning efforts to highlight what needs to be considered in this type of approach, how that varies spatially based upon overall watershed protection goals, the realities of cost and engineering constraints, and how different objectives can shift recommended solutions and SCM distribution across a watershed. These sensitivities and tradeoffs will be demonstrated with examples from extensive modeling studies and planning efforts from the Los Angeles region with comparisons to how these results would differ in regions beyond so that these lessons can be applied wherever managers are taking on this type of watershed-wide approach.
