Water Resources Collections and Archives

The Zone 7 Water Agency uses concrete V-ditches to manage stormwater runoff from access roads near creeks. We attempted to find a way to manage runoff that would filter the stormwater and cost less than concrete V-ditches. Using Tassajara Creek in Dublin, California, as a case study, we designed a low- maintenance vegetated strip that would be capable of filtering pollutants from runoff, even while conveying the expected Q100 flow of 0.451 cfs. Our vegetated strip would cost $5-$10 per linear foot, compared to $16 per linear foot for Tassajara Creek’s Vditches. Zone 7 could adopt this design without changing any of its guidelines for managing runoff from access roads. Because Zone 7 has more confidence in the performance of concrete channels during high flows, we recommend that Zone 7 implement our design on a trial basis and monitor its performance.