Shamrock 5k Fun Run and Walk

“Beginning July 1, 2024, the “Honest Pricing Law” or “Hidden Fees Statute,” SB 478, makes it illegal for businesses to advertise or list a price for a good or service that does not include all required fees or charges other than certain government taxes and shipping costs.”

RACE INFO: We are so excited to celebrate the 42nd annual Lake Chabot Trail Challenge Half Marathon and 5K. This race is well regarded amongst serious trail runners in the outlying areas. The race begins at 8am for the Half Marathon and 8:30am for the 5K. Please arrive early so that you may find parking, pick up your bibs, use restrooms facilities, and be properly prepared to race before the start. Race takes place rain or shine and there are no refunds.

RACE COURSE: The half marathon course is a scenic, hilly loop, mainly on dirt fire roads. The ridge-line views look down upon scenic Lake Chabot, surrounding grassy slopes, and eucalyptus groves. Mt. Diablo and San Francisco Bay are visible along the route. There are water stations with first aid and radio support; we recommend bringing your own hydration as well. The half marathon has a time limit of 3.5 hours. The 5k (3.1 miles) course is an out and back that has gentle rolling hills and consists mostly of paved surfaces. This route includes one water station with first aid and radio support.

RACE FEE: Pre-registered runners will be guaranteed a t-shirt if registered by Sunday, May 10th, 2026. The price for the 5K is $40 and Half Marathon $65. You must register by Saturday, June 6th. We will accept race day registration; however, the price for the 5K is $45 and Half Marathon $70. If you register on race day, we can only accept cash, check or Venmo.

There is a nominal fee (~$5) for Chabot parking lot. Free parking on Lake Chabot Rd and nearby streets.

RACE PACKET & BIB PICK-UP: We will have race packet and bib pick-up on Sunday, June 7th starting at 7am at the Willow picnic site which is also the finish line area. We will not be mailing out any race packets or bibs. Both races are chip-timed.

T-SHIRT: Entry fee includes short sleeve, high quality t-shirts for registrations by May 10th so sign-up early. There are no guarantee of t-shirts for runners registered after that date and on race day. We ask for those who did not get a shirt to check in after the race. Please ensure that you select the appropriate t-shirt size. We will not be doing any size exchanges from your original request.

AWARDS: Finisher's medals to those who complete their race. Age division medals given to the top 3 in each of 12 age divisions in the half marathon and 9 age divisions in the 5K.

Photos: Race photos are being provided by Darrell Lavin of Darrell Lavin Photography. You will receive an email post-race for instructions on how to access and purchase official race photos.

QUESTIONS: If you have any questions, please contact Rachel Lunt at [email protected].

DIRECTIONS: The entrance closest to the event's parking lot is: 17404 Lake Chabot Road, Castro Valley, CA 94546. On Google Maps, this will appear as "Entry of Lake Chabot Parking Space." The registration area and start lines are just a few minutes walk from the lot ( just follow the signs).

Rising up from the depths of Lake Chabot, the Bad Bass (a strangely kilt-wearing, bagpipe-playing Scottish bass with teeth) shows itself once again on July 18th 2026! Why is he Scottish? What is he doing in Castro Valley? How can he play bagpipes with his fin? We have no idea how to answer those questions. Why is he so bad-to-the-fishbone? Maybe he just knows how awesome the trails of Lake Chabot really are!

Whatever the Bad Bass is doing here, we hope you'll join us at the beautiful Lake Chabot Marina in Castro Valley for the scenic Bad Bass 5K, 10K or Half Marathon!