⏵ Course guide · East Bay watershed trails
Reservoir Dogs sends the 35K field on a full circumnavigation of Briones Reservoir, normally permit-only East Bay Municipal Utility District (EBMUD) land, on rolling fire roads and twisty singletrack near Orinda. I will walk you through the course first, then give you a pacing and fueling plan built for this cupless, gently rolling East Bay 35K. There are free calculators along the way to dial in your own numbers.
These facts come from the official Inside Trail Racing event page. Check the current year details, cutoffs, and aid stations before you commit. Race logistics change year to year.
Reservoir Dogs was the first trail race allowed to fully circumnavigate Briones Reservoir on EBMUD land, trails that are usually closed to the public. The 35K, Half, 10K, and 5K all start and finish at the San Pablo Reservoir Visitor Center.
The course runs gently rolling the entire way, mixing open fire roads with fun, twisty single and double-track trails through tree-covered sections and along the watershed. It is moderately technical in spots but nothing like the steep, punishing climbs found at some of Inside Trail's mountain races, which is exactly why the organizers call this one of their faster courses.
Expect a progression of classic East Bay environments: open rolling hills, tree-covered singletrack, and sweeping views of the watershed lands around Briones and San Pablo Reservoirs. It is a scenic, approachable course that rewards steady effort over technical skill.
This is a cupless event, so plan to carry at least one 20-ounce bottle or a reusable soft flask. Aid stations still carry a full spread: Gu gels and chews, Gu Stroop Waffles, trail mix, pretzels, chips, Oreos, PB&J, boiled potatoes with salt, Coke, Ginger Ale, water, and Skratch Labs hydration mix. Reusable cups and soft flasks are available for purchase at the event if you show up without one.
With about 2,500 feet of gain over 23 miles and a 6.5 hour cutoff, this course rewards even effort on the rolling terrain more than raw climbing strength.
The constant rolling terrain means your effort should stay steady even as your pace naturally varies between the climbs and the fast, fun descents. A grade-adjusted pace target gives you an honest number for the whole 23 miles, rather than one that only makes sense on the flats.
A vert-aware finish prediction, built off the roughly 2,500 feet of gain and the terrain mix, is a better guide than a road 35K time. Check it against the 6.5 hour cutoff early so you have room to adjust effort rather than scrambling in the final miles.
⏵ Free tools to pace this course
An 8:00 AM start on a 6.5 hour clock means most 35K finishers wrap up by early afternoon, but East Bay October days can still warm up fast once the fog burns off.
Aim for roughly 60 to 90 grams of carbohydrate per hour. The aid stations carry Gu gels and chews, Stroop Waffles, and real food like PB&J and boiled potatoes, so you have options whether you prefer gels or solid food. Since this is cupless, plan your bottle refills at each stop rather than assuming you can grab a quick cup and go.
Sodium in the 300 to 700 mg per liter range covers most runners here. Skratch Labs hydration mix at the aid stations runs about 800 mg sodium per liter, so lean on it if the day heats up once you are out on the exposed rolling sections.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and this cupless East Bay course with the free ultra fueling calculator. Browse the rest of the free running tools at the tools hub.
⏵ Train for it with Summit Line
Get a race-day plan built around YOUR fitness, this exact rolling reservoir course profile, and your projected splits. Summit Line reads your real training, builds a plan for rolling East Bay terrain, and rehearses your fueling so race day is something you execute, not guess at.
It is one of the friendlier entries in the Inside Trail Racing calendar, and the organizers say as much: the 10K, Half, and 35K are faster than other ITR races because they carry less elevation. That said, the 35K still climbs roughly 2,500 feet over 23 miles of rolling fire roads and twisty singletrack around Briones Reservoir, and the 6.5 hour cutoff means you cannot dawdle. Treat it as a good gateway 35K rather than a mountain test.
The 35K carries about 2,500 feet of gain over its 23 miles, the Half Marathon about 1,400 feet over 14 miles, the 10K about 425 feet over 6.2 miles, and the 5K about 200 feet over 3.1 miles. None of that is severe by East Bay standards. The course is described as gently rolling the entire way, with fire roads and fun twisty single and double-track rather than one defining climb.
This is a cupless event, so you need your own bottle or reusable cup, but the aid stations still carry a full spread: Gu Energy gels and chews, Gu Stroop Waffles, trail mix, pretzels, chips, PB&J, boiled potatoes with salt, Coke, Skratch Labs hydration mix, and salt tablets. For a 35K finishing inside 6.5 hours, aim for roughly 60 to 90 grams of carbohydrate per hour and sodium in the 300 to 700 mg per liter range, leaning higher if the October East Bay day runs warm. Build your numbers with the free ultra fueling calculator before race day.
The Half Marathon and 35K both carry a 6.5 hour time limit, and every runner must be off the course by 2:30 PM given the 8:00 AM start. The 10K and 5K, starting later at 8:30 and 8:45 AM, are not stated with a separate hard cutoff on the official page, but plan to finish well within the morning given the same course closure window.
The course circumnavigates Briones Reservoir on East Bay Municipal Utility District (EBMUD) watershed trails, normally permit-only land that this race opens up for a full loop. Expect moderately technical dirt trails and fire roads, gently rolling hills throughout, and a mix of tree-covered singletrack with sweeping views over the reservoir and surrounding hills.
Yes, the 35K is a reasonable first-ultra choice. The elevation is modest for the region (about 2,500 feet over 23 miles), the course is described as rolling rather than mountainous, and the 6.5 hour cutoff gives a well-prepared newcomer real room. The main adjustment for first-timers is the cupless format, so practice carrying your own water before race day.
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<a href="https://runsummitline.com/guides/reservoir-dogs-trail-run">The Reservoir Dogs Trail Run course guide</a>This guide is independent and for planning only. The course details, dates, cutoffs, and aid stations come from public sources and can change year to year, so confirm the current specifics with the official race before you register or run. The fueling and pacing advice is general and not medical advice.