Oceano Drainage Improvements

Since the 1950’s, the coastal community of Oceano experienced chronic flooding during storm events due to insufficient storm drain capacity. The flooding was compounded by the Arroyo Grande Creek’s reduced capacity over time from sedimentation and dense vegetation growth. The Oceano Drainage Improvement Project was implemented to solve roadway flooding.

Two locations in Oceano experienced the heaviest flooding: 13th Street at Highway 1 and 17th-19th Street at Highway 1. To alleviate these drainage issues, the County of San Luis Obispo selected Cannon to design and engineer new storm drain improvements. The design called for new storm drain facilities near and around the intersection of Highway 1 at 13th and Paso Robles Street, additional storm drain facilities within 15th street and the Paso Robles Street intersection, a concrete sedimentation basin in the RV Storage Lot near Arroyo Grande Creek, a box culvert through the Arroyo Grande Creek levee, and roadside infiltration systems within the existing residential community.

The project has now been fully constructed and tested through a rainy season. The improvements successfully alleviated flooding of Highway 1 during small storm events and rerouted stormwater flows away from Meadow Creek Lagoon into Arroyo Grande creek with the new underground storm drain system and detention basin.