⏵ Course guide · Diamond Valley Lake trail race
Bedrock Valley Trail Runs loops a relatively flat course around Diamond Valley Lake near Hemet, California, with a Trail Marathon, Half Marathon, 15K, 10K, and 5K all sharing the same lakefront terrain. I will walk you through the course first, then give you a pacing and fueling plan for a warm Southern California morning. There are free calculators along the way to dial in your own numbers.
These facts come from the official RunSignup registration page. Check the current year details, cutoffs, and aid stations before you commit. Race logistics change year to year.
Every distance shares the same Diamond Valley Lake setting. The marathon is two loops of the half marathon course, ending on double track, while the shorter distances run their own out-and-back and loop variations.
Elevation Culture describes the marathon as "a relatively flat loop around the lake ending with some beautiful double track," and calls it "ideal for all running levels." The half marathon is a beautiful out-and-back along the lakebed. This is a course built around distance and consistency, not technical climbing.
Diamond Valley Lake sits on ground where the most concentrated deposit of mastodon fossils in the region was uncovered during the lake's construction, alongside other Ice Age remains. You are literally running over that history on race day.
This is a cupless event: bring your own hydration vessel, since aid stations do not provide disposable cups. Course wristbands match your distance markings, a small but useful detail if you are running with runners doing a different distance.
Without major elevation change to manage, pacing here is more about heat and distance discipline than climbing strategy.
A flat course invites a fast start, but the marathon is still two full loops, and Southern California mornings can warm up quickly by the second lap. Hold a consistent pace rather than banking early speed you cannot sustain into the later miles.
The marathon has 6 hours from its 7:00 AM start to the shared 1:00 PM course closure. Use your first loop split to confirm you are comfortably inside that window before committing to the second loop at the same effort.
⏵ Free tools to pace this course
Early April in Riverside County can warm up fast once the sun is up, and a lake loop offers limited shade across most of the course.
Aim for roughly 60 to 90 grams of carbohydrate per hour on the marathon, and sodium in the 300 to 700 mg per liter range, leaning higher if the day warms up faster than expected. Remember to bring your own cup or bottle since this is a cupless event.
Because the marathon repeats the same loop twice, you get predictable aid access at consistent points. Use that predictability to plan exactly how much you carry between stops rather than guessing.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and a warm Southern California morning 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 Diamond Valley Lake profile, and your projected splits. Summit Line reads your real training, builds a plan for a warm flat marathon, and rehearses your fueling so race day is something you execute, not guess at.
Elevation Culture describes the Bedrock Valley marathon course as "a relatively flat loop around the lake ending with some beautiful double track," and does not publish an elevation gain figure. The shared 1:00 PM course closure gives marathon runners a 6 hour window from a 7:00 AM start, which is generous for a flat course. This reads as an approachable trail marathon rather than a mountain test, a good fit for runners building toward a harder objective.
Six run distances: a Trail Marathon (two loops of the half marathon course), a Trail Half Marathon, a 15K, a 10K, a 5K (billed as the Stampede 5K), a Stroller Trail 5K, and an Elevated Youth 1 Mile. A separate gravel bike ride follows the next day.
Early April in Hemet, California can run warm by mid-morning, especially on a relatively flat, exposed lake-loop course with limited shade. Aim for roughly 60 to 90 grams of carbohydrate per hour on the marathon, and sodium in the 300 to 700 mg per liter range. This is a cupless event, so bring your own hydration vessel since no disposable cups are provided at aid stations. Build your numbers with the free ultra fueling calculator before race day.
Every distance shares the same 1:00 PM course closure. That gives marathon runners 6 hours from their 7:00 AM start, half marathon runners 5.5 hours from 7:30 AM, and the shorter distances proportionally more room given their later starts.
The course loops around Diamond Valley Lake on a relatively flat route, with the marathon finishing on double track. The 15K mixes flat, fast double-track trail, while the 10K and 5K run as fast out-and-backs with lake views. It is a scenic but approachable profile rather than a technical mountain course. Diamond Valley Lake itself sits on ground where the largest concentration of mastodon fossils in the region was discovered during the lake's construction.
Yes. A relatively flat lake-loop course, a generous 6 hour cutoff, and well-stocked aid support make this a reasonable first trail marathon if you have some road marathon or shorter trail race experience. The double-track finish and lack of major elevation change mean the challenge is more about pacing a full marathon distance than surviving technical terrain.
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<a href="https://runsummitline.com/guides/bedrock-valley-trail-runs">The Bedrock Valley Trail Runs 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.