Boulder Rez Marathon, 3/4 Marathon, Half Marathon, 10K & Relay
August 14th 2021
Boulder Reservoir, Boulder, Colorado
Race Distances

Marathon 26.2mi (4 laps)

3/4 Marathon 19.65mi ( 3 laps)

Half Marathon 13.1mi (2 laps)

10K 6.2 miles

This amazing run course will take you alongside the Boulder Reservoir, remaining mostly on dirt roads and trails. The course is flat with only 200 feet of gain, and will provide views of the Boulder Reservoir and Rocky Mountains.


  • Scenic, mountain and water course views 

  • ​Run entirely around the Boulder Reservoir

  • Spectator-friendly course

  • BolderBOULDER qualifier

  • Age Group awards for all distances

logos_nuunhydration_tshirt .jpg
El Dorado.png
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 Stations will be located approximately every 1-2 miles. Remember, all distances will run the 6.2mi loop around the Rez, so you will hit these aid stations multiple times during the Half, 3/4 and Full Marathon.


Event Schedule

6:00am - 7:15am: Packet Pick Up & Registration

7:15am: Start of Marathon

7:20am: Start of the 3/4 Marathon

7:25am: Start of the Half Marathon

7:30am: Start of 10K

8:45am: 10K Overall Awards

9:30am*: Half Marathon Awards

10:30am*: 3/4 Marathon Awards

11:30am*: Full Marathon Awards

2:00pm: Course Closes

*Award times are approximate

Packet Pick Up

Friday, August 13th, 2021

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

Saturday, August 14th, 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

  • Reliable, Accurate Results

  • Post-Race Food

  • Participant Shirt

  • Finisher Medal

  • Digital Goodie Bag

  • Overall AwardsAge Group & Relay 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 a commemorative certificate.

  • 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 Results & Photos

Contact Us

  • Black Instagram Icon
  • Black Facebook Icon

Copyright © 2020  All Rights Reserved   BBSC Endurance Sports, LLC