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Lake Chabot

Bad Bass Half Marathon, 10K & 5K

July 19, 2025
Castro Valley
Trail
Distances
Half-Marathon, 10k, 5k
Starting Time

8:30 AM

Fees

$92+

Perfect For
100-500
Some Hills
Lakefront
High: 80°
/ Low: 60°
Overview
Runners follow an out-and-back course for the the “Bad Bass” Half Marathon along a combination of paved and natural-surface trails along the shoreline of California’s Lake Chabot, which doubles both as a drinking water reservoir for the East Bay area and as a recreational park, filled with more than 20 miles of hiking trails as well as the 315-acre lake that draws visitors year-round for fishing and boating. All three races in the event start and finish at the Lake Chalbot Marina, which lies at the southernmost tip of the lake just off Fairmont Drive. From there, runners in the half marathon follow a counter-clockwise out-and-back loop route that takes them first northward around the eastern side of the lake, along which runners can expect both paved trails and later natural trails through the woods along the lakeshore. (Organizers say that over the course of the half marathon, the surface is roughly half paved and half natural trails.)

The 5K is entirely on paved trails.  The 10K is about 50% paved trails and 50% fire trails.  The half marathon is approximately 25% paved trails and 75% fire trails.

The 5K and 10K will essentially be out and back courses, while the half marathon is a loop.

All courses include rolling hills that are mostly runnable — except for the climb up Live Oak for the half marathon and 10K that is best power-hiked!

Bad Bass Half Marathon, 10K & 5K Course Map

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