Sacramento River: Fremont Weir and the "Big Notch"

Time for a trip to the Sacramento River. This outing shifts from geology to the natural‑science dynamics of the Fremont Weir and Yolo Bypass—how engineered river structures interact with a living Central Valley landscape. We’ll walk west along the top of the weir to see how water, sediment, vegetation, and wildlife respond to seasonal flooding.
Hike is about 4 flat miles

🔍 What We’ll Explore

Flood hydraulics — How high water overtops the 32‑ft weir, slows in the bypass, and drops fine sediment that shapes the floodway (not likely to be anywhere near this high in October!).
Legacy flood features — Scour ponds, stilling basins, and old river meanders preserved within the floodway footprint.
Riparian vegetation zones — A clear moisture gradient from dry levee grasses to cottonwood–willow riparian canopy and tule wetlands.
Wildlife corridors — Perennial ponds supporting native fish (e.g., Chinook salmon, steelhead) and riparian habitat used by raptors like Swainson’s hawks.

📍 Why This Area Matters

The Fremont Weir is a rare place where you can directly see engineered water control, sediment deposition, wetland ecology, and wildlife movement all operating in one corridor.

📍 Logistics

$2 contribution requested to help with Meetup fees (hat passed at the start of the hike.
First 15 minutes is background info and waiting for late comers; we'll start hiking at about 10:15.
Bring binoculars if you have them; we'll likely be able to spot some nice birds.
Bring snacks/lunch. We'll have a 20-30 minute lunch break at the turn-around point.
Kids are welcome
No dogs.

📍 More details

The hike on AllTrails
DWR launches operations at Big Notch Project, expanding critical salmon habitat
A long video about the area; Big Notch is focused on around 46:30.