Develop Solutions to Enhance Habitat and Reduce Flooding Along Butano Creek

A cbec-Stillwater Sciences team was contracted to develop solutions to enhance in channel and off channel habitat while also reducing the frequent flooding of Pescadero Creek Road at Butano Creek. The project encompassed portions of the Pescadero Marsh Natural Preserve, managed by California State Parks, as well as the reach of Butano Creek upstream of the Marsh that is privately owned. A number of listed species (e.g., coho salmon, steelhead, tidewater goby, red-legged frog and San Francisco garter snake) use the creek, marsh and lagoon areas, and successful solutions to the flooding must also enhance conditions for these species.

cbec’s tasks included topographic surveys, hydrodynamic and sediment transport modeling, scenario development and evaluation, as well as extensive stakeholder outreach and meeting facilitation. Cross-section data were collected along a 5-mile reach Butano Creek with RTK-GPS and total station surveying equipment to provide data that were not previously available. Sediment samples were also collected in this reach. A one-dimensional unsteady hydrodynamic and sediment transport model was developed using HEC-RAS to evaluate: 1) the flood benefits in the near-term and in the future (i.e., after 10 years of typical hydrology), 2) the resulting amount of aggradation and/or transport of sediment, and 3) the ecological benefit or impact resulting from a variety of proposed solutions.

Components of solutions evaluated included channel dredging, channel realignment, road/bridge modification, vegetation removal, floodplain lowering, floodplain reconnection and large wood addition. The project led to the implementation of several positive and successful actions, including the Butano Farms Floodplain Restoration Project, the Butano Creek Channel Reconnection Project (implementation began in 2018 and will be finished in 2019), and a feasibility study for an improved bridge, that was regrettably discontinued midway through the effort.