Boulder Rez Half Marathon, 10K & 5K Run 

Boulder Reservoir, Boulder, Colorado

June 6, 2021

The Spring Boulder Rez Half Marathon, 10K and 5K is quickly becoming a Boulder favorite! And, the incredible Colorado weather in the end of May couldn’t be better for hitting your new PR. Athletes travel from all over the US to run on this phenomenal course, with views of the Flatirons painted in the distance. Bring your friends and family to cheer you on, this is a spectator-friendly course. All participants will receive a glamorous finisher medal, cool shirts, and a goodie bag full of samples! We will host an awards ceremony and post-race party with beer, food, race expo and the chance to win prizes too!

Race Venue

Boulder Reservoir

5565 N 51st St. Boulder, CO 80303


Athletes and spectators must park in the gravel lot adjacent from the paved parking area. Please follow parking attendants, directing traffic inside the park. 

Half Marathon 13.1mi

10K 6.2 miles

5K 3.1 miles

Race at the Rez

This amazing run course around the Boulder Reservoir is astonishing and remains mostly on dirt roads and trails. The course is flat with only 200 feet of elevation gain. The route will take you around the the Boulder Reservoir, where you will experience iconic views of the mountain range to the west.

The Half Marathon will complete 2 loops, and the 10K will complete one loop. 5K runners will run counterclockwise for 1.55 miles and then head back to the finish line in the parking lot area.


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Aid Stations

Aid Stations will be stocked with water, gels and a hydration drink. Snacks, music and other goodies will be available at special aid stations. Fluids will be available in small disposable cups, though the aid stations will be happy to refill your own water bottle as well, should you chose to carry one. Please dispose of cups in designated drop areas. We are a green event that will recycle all cups after the race!



Aid Station Mile Markers along the course: 1.0, 2.0, 3.1, 4.2, and 5.

Remember, the Half Marathon course makes 2 laps around the Rez, so you will hit these aid stations multiple times during the Half Marathon.


Event Schedule

6:15am - 7:15am: Race Day Packet Pick-Up

7:15am: Start of the Half Marathon

7:20am: Start of the 10K

7:25am: Start of the 5K

8:05am: 5K Awards

8:45am: 10K Awards

9:30am: Half Marathon Awards

10:45am: Course Closes

Packet Pick-Up

Saturday, June 5, 2021

Boulder Running Company, 2775 Pearl St, Boulder, CO 80302

Sunday, June 6th, 2021

Finish Line Area, 5565 N 51st St. Boulder, CO 80301

Race Features
  • Scenic, USATF sanctioned course

  • Early & Race Day Packet Pick-Up Options

  • Accurately measured, clearly marked courses

  • Timing & Immediate Race Results

  • Post-Race Food

  • Participant Shirt

  • Finisher Medal

  • Digital Goodie Bag

  • Overall Awards & Age Group Awards

Race Entry Fees

 The top 3 overall men and women in each distance will receive an award. The top 3 men and women in each distance will be awarded in each age group. Age Group winners will receive an award.

  • 19 & Under

  • 20-29

  • 30-39

  • 40-49

  • 50-59

  • 60-69

  • 70-79

  • 80+


Volunteers of all ages are welcome! Volunteers under 13 years must have a parent or guardian accompanying them during their volunteer shift. Please email to inquire about volunteering. Include your name, age, day & time availability, and any special requests.

Past Race Results

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