Fish Passage Improvements
Resting pools help fish and add visual interest. |
San Lorenzo Creek was a historical migration route and habitat for steelhead trout and coho salmon. As recently as 1975, rainbow trout lived in Don Castro Reservoir and migrated upstream to spawn. Fish still regularly swim up through the earthen levees area into the concrete-lined flood control channel where they encounter barriers, low water flow and a lack of resting pools. Many of the trees and the vegetation that would naturally hang over the creek and cool the water have been removed. As a result, the water temperature is too high for coldwater fish such as steelhead.
For fish passage improvements to be feasible, they must also maintain or improve the current channel water flow capacity and be low-maintenance (not trap debris or sediment).
The District is developing concepts that could enhance fish passage and the surrounding riparian habitat, such as:
- A series of resting pools in the concrete channel where fish could stay waiting for high water flows, as shown in the conceptual drawing.
- Pool-weir fishway to help spawning fish migrate from the concrete channel to the natural area above Foothill Boulevard.
- Planting native trees and vegetation to shade the water.
- A low-flow channel in Don Castro Reservoir that would release cooler water from the bottom of the reservoir, rather than the warmer top water (this would also help reduce silt buildup).
- Increase creek stewardship and monitoring of water quality and trash.
- Use bioengineering methods rather than hardscapes to stabilize creek banks.
