Until the 1980s, the Mt. Diablo Creek watershed supported a steelhead trout population. In the 1980s, earth moving related to subterranean pipelines near the mouth of Mt. Diablo Creek at Suisun Bay blocked access to the entire watershed. A debris gate in the middle watershed, modified in 2002, may block passage at some flows. For the past 70 years, steelhead access has been denied to pristine habitat in the upper reaches of Mitchell Creek (a main tributary) by two dams and a culvert. This proposal seeks funding to plan, design, and implement the necessary fish passage projects through out the watershed to restore steelhead access to 15 miles of stream habitat. An existing watershed inventory identifies removal of these barriers as critical to steelhead repopulation. The watershed assessment produced in coordination with the stakeholder-driven planning process identifies the potential for restoring steelhead to the watershed and called for detailed studies to restore passage.
Reliable reports of steelhead trout in Mt. Diablo Creek date as recent at 1988 and as early as 1855. The lower barrier occurs in the between freshwater and tidal wetlands. Earth that covers 3 subterranean pipelines blocks the channel. Water ponds behind the barrier creating flooding, mosquito habitat, and prevents transport of sediment to the subsiding tidal marsh immediately downstream. The middle barrier is a debris gate modified around 2002 at the boundary of the Concord Naval Weapons Station. The upper barriers are approximately 6-8 feet in height each. Though they no longer provide the intended benefits, they maintain the grade of the creek and appropriate actions may either be full removal, a reduction in height, and/or placement of boulders or other fish ladder-type structures to make the area passable to fish. A culvert, immediately upstream, provides a stream crossing for a fire road in the park. It is perched 4 feet above the thalweg of the channel blocking passage.
This project will complete the necessary planning, technical studies, design work and physical modifications to implement steelhead trout passage through out Mt. Diablo Creek watershed. At the completion of the project, we will restore steelhead passage to 15 miles of excellent steelhead habitat. In addition to passage, this project will eliminate a public health nuisance, a flooding problem, an impediment to operations of the Mokelumne Aqueduct, and restore necessary sediment inputs into a subsiding tidal marsh. It will avoid the redundancy and inefficiency of separate fish passage planning projects, coordinate between involved parties and landowners, avoid unnecessary impacts to adjacent habitats.
Watershed Management, Fish Passage, Funding/Financing, Creeks, Habitat Protection, Steelhead, Stakeholders
Ecosystem Restoration,
Environmental and habitat protection and improvement,
Flood management,
Watershed planning,
Wetlands enhancement and creation
