Develop Solutions to Enhance Habitat and Reduce Flooding Reduction Along Butano Creek
cbec was contracted to develop solutions to enhance aquatic and wetland habitat while also reducing the frequent flooding of Pescadero Creek Road at Butano Creek.
The project encompasses 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 a successful solution to the flooding must also enhance conditions for these species. For example, it is currently believed that steelhead and coho salmon are not able to gain access to high quality habitat located in the Butano Creek watershed due to aggradation that has occurred in the channel.
cbec teamed with a biological firm to develop physical solutions to the sedimentation and resulting flooding problem, while concurrently enhancing habitat and access for listed species.
cbec’s tasks include field work, hydrodynamic and sediment transport modeling, scenario development and evaluation, as well as stakeholder 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.
An unsteady hydrodynamic and sediment transport model was developed using HEC-RAS to evaluate:
- Flood benefits in the near-term and in the future.
- Resulting rate of aggradation and/or transport.
- Ecological benefit or impact of previously proposed solutions.
In addition, new solutions were developed and are currently being evaluated. Components of solutions include channel dredging, channel realignment, road/bridge modification, vegetation removal, floodplain lowering, and large wood addition. Once a preferred solution has been selected, cbec will develop conceptual-level drawings.