
Enumclaw, United States of America · Saturday 30 May 2026
May 30, 2026 – The Full Marathon Returns! We’re excited to announce that the Full Marathon is coming back on May 30, 2026, and will also be part of our September event. Start planning now for your next Boston Qualifier on this beautiful, fully paved downhill course, no tunnel, no dirt, no BQ penalty. There’s no excuse not to do the dam thing! Marathon The marathon course begins at Mud Mountain Dam (elevation 1,400′). Runners will follow a fully paved route through picturesque farmlands and forested areas, tracing the path of the Carbon River. The race finishes in front of the historic McMillin Bridge (elevation 200′), with a total net elevation loss of approximately 1,200′. Half Marathon The Half Marathon begins in the scenic town of South Prairie (elevation 467′) and follows a gradual downhill route along the paved Foothills Rail Trail. Runners will enjoy a picturesque journey through farmland and forest, winding alongside the Carbon River and finishing in front of the historic McMillin Bridge (elevation 128′). The course features a net elevation loss of 339 feet.
Adjusted Time
1:39:47
Time difference: -5.2 minutes compared to a flat, road, temperate course.
Spring - Mud Mountain Dam Marathon & Half Marathon is a half marathon held in Enumclaw, United States of America, scheduled for Saturday 30 May 2026. The course is run on road surface with 0m of total elevation gain, reaching a maximum altitude of 0m above sea level. For registration and full race details, visit the official Spring - Mud Mountain Dam Marathon & Half Marathon website.
This is a very flat course with only 0m of total elevation gain across the full distance. The course ranges from 0m to 0m above sea level — a 0m elevation range that makes it one of the flatter races available. Runners targeting a personal best will appreciate the minimal climbing.
Based on historical weather data for May, the expected race day conditions are as follows. Near-ideal running temperatures are expected, ranging from 9°C to 16°C. This temperature range is widely considered optimal for marathon performance, allowing efficient heat dissipation without cold-related issues. There is a low chance of rain (5%), so dry conditions are likely.
Spring - Mud Mountain Dam Marathon & Half Marathon is run on road surfaces, which provide the fastest and most predictable conditions for marathon running. Road courses allow for consistent pacing and are typically the best choice for runners targeting a personal best time.
Our difficulty rating for Spring - Mud Mountain Dam Marathon & Half Marathon is calculated using a model that combines elevation gain, temperature impact, and surface type. Use the difficulty calculator above to enter your target finish time and see exactly how many minutes this course would add or subtract compared to a perfectly flat, cool, road-based half marathon. Faster runners and slower runners are affected differently by the same course conditions, so the difficulty is personalised to your pace.
Looking for an easier marathon or a tougher challenge? You can also compare Spring - Mud Mountain Dam Marathon & Half Marathon against other half marathons to find the right race for your goals.
San Diego, United States of America
Kailua, United States of America
Irving, United States of America
Long Beach, United States of America
Charlottesville, United States of America
Wilmington, United States of America