July 2026: Mill Valley StreamKeepers Funds New Study of Old Mill Creek

Recently, Mill Valley StreamKeepers funded a new study conducted by renowned fish expert Ross Taylor (with help from Marin RCD's Sarah Phillips and GeoMorph's Matt Smeltzer) which shows that there is a good presence of salmonids including Steelhead and Rainbow Trout in Old Mill Creek. The study also identifies the fish passage barrier at the bridge at Cascade Drive as the best prospect for removal and improvement in the Arroyo de Corte Madera del Presidio (ACMdP) watershed.

Click here for the report.

Also, here's an exciting video taken by a neighbor on Sycamore Avenue in ACMdP in April 2026.

Ross Taylor says that is definitely a steelhead (based on timing and that square tail), and a female steelhead based by her short rounded snout and she looks full of eggs. There is a smaller resident fish that's closely following the female steelhead, it's a likely male resident coastal rainbow trout who wants to spawn with her.

Finally, here are some pictures of the Cascade Drive bridge and its fish barrier/dam, along with a photo from November 2024 when several 3 foot long salmon got stuck just downstream of the barrier.

Cascade Drive Bridge in Old Mill Park

This is one of the fish barriers near the bridge.

One of the salmon prevented from moving upstream beyond the bridge in November 2024.