6 running, swimming, and triathlon events in Saint Peters, Missouri

Join MSE Racing and Coach Sally Drake for an open water swim session/clinic at beautiful 370 Lakeside Park in Saint Peters.

We will kick off 370 Lakeside Triathlon and Expo weekend with an optional swim clinic to help newbies prepare and gain helpful tips for open water swimming and race day strategies. For those with experience, just swim and enjoy! We will have a couple of buoys for use at the clinic session, but not full access to the triathlon swim courses because the park will be open to the public that day.

This event is open to anyone at any level. We offer a special discounted rate for athletes participating in the Lakeside 370 Triathlon if you bundle and purchase the Open Water Swim Clinic Session when you register for the 370 Lakeside Triathlon.

During the session lifeguards and volunteers will be in the water to ensure the safety of the participants, there will also be buoys setup in the water to practice sighting. After the swim, please stick around for the MSE Lakeside 370 Triathlon Expo.

For more information please visit - https://www.mseracing.com/370-lakeside-open-water-swim

Join us for the 6th annual USAT sanctioned 370 Lakeside Triathlon! Enjoy the flattest, fastest course starting in beautiful 370 Lakeside Park! Enjoy a beach start, amazing country roads in St. Charles County, and a run that includes the park trails. We offer a variety of race options from a 5k run, super sprint or sprint for newbies, up to half distance along with duathlon, aquabike and aquathlon options!

For more information including course maps, schedule of events, race options, volunteer signup, etc. Please visit - https://www.mseracing.com/370-lakeside-triathlon

All athletes MUST show a Photo ID and pick up their own race packet, NO EXCEPTIONS.

***St. Louis Track Club members will automatically receive a $10 discount (use the same email address that you use for your member registration). Not a member? Click here to join. ***

St. Louis Track Club is excited to invite everyone to join the Corps of Discovery Trail Races, held on the Lewis & Clark Trails in the beautiful Weldon Spring Conservation Area on August 29, 2026.

Course Description:

The half-marathon course covers approximately 13.1 miles and begin from the Lewis & Clark trailhead in the Weldon Spring Conservation Area off Hwy 94 in Defiance, MO. Half marathon participants will first run the 8-mile Lewis Trail and then the 5-mile Clark Trail. The course will travel counter-clockwise and will not be closed to outside use. There will be markings along the course and a volunteer where the trails split.

The 5-mile distance will cover one loop of the Clark trail and the 8-mile option will cover one loop of the Lewis trail. The trail winds itself along the bluffs of the Missouri River down the hardwood-lined ridges and into the hollows so all participants will have something to enjoy.

All distances start at 8:00 a.m.

Half Marathon Course Map

8 mile Course Map

5 mile race Course Map

Sign up before August 15th to guarantee swag! All runners registered before this date will receive swag and a finisher's medal.

Thank you to our sponsor Tailwind Nutrition!

Race Day Details:

CUP FREE: This race is a CUP FREE event. This means that there will be NO paper cups at any of the aid stations. Please carry a water receptacle and fill up as needed with water and/or Tailwind, both of which will be available throughout the course.

PARKING: Parking is in the secondary lot at the Weldon Spring Interpretive Site (7295 RT-94, St. Charles, MO). Please follow the signs and park where guided so as to leave room on the main lot for other trail patrons.

PACKET PICK-UP: All racers can pick up their packets near the parking lot and race start line on race morning starting at 6:30 am.

CUT-OFF TIMES: The cutoff time is 12 p.m., or 4 hours. This is approximately an 18-minute pace per mile. The half marathon course brings runners to the Lewis and Clark trailhead at 8ish miles before heading out to do the final 5-mile loop on Clark. Runners must start their 5-mile loop by 10:30am.

DROP BAGS: We will have a drop bag collection area at the start/finish area. Please mark the bag with your name in case someone has the same one.

RACE START: All distances will start and finish at the Lewis and Clark trailhead. The 5 mile runners will start in quick waves starting at 8 AM and the Half Marathon and 8 milers will start in quick waves at 8:05AM. Since parking is across the roadway at the Weldon Spring site, we will have cones set up to warn drivers and give runners a safe way to be along the roadway. Be sure to pay close attention to the roadway and take caution as you cross.

AID STATIONS: 5 Mile: One manned aid station at mile 3 (water, electrolyte drink, and snacks), plus water and support at the finish line. 8 Mile: An unmanned water-only station around mile 4, and a manned aid station at mile 6.5 (water, electrolyte drink, and snacks). Half Marathon: Runners complete the Lewis loop first, with access to those same stations. They then pass through the start/finish area around mile 8.2 (fully stocked), followed by a final manned station near mile 12 (water, electrolyte drink, and snacks) before returning to the finish.

Join us for the annual Candy Cane Course 5k/10k/15k! A fun, Christmas-themed event that is perfect for the whole family.

The fun includes -

• Great Swag - designer shirt & custom medal

• Chip-timing with live results and awards

• Free photos

• Delicious Treats waiting at the finish line

• Plenty of fun!

Grab your friends and family, you are not going to want to miss this one!

Can't make the race? No problem! We offer a virtual race option where you can run anywhere, at any time, and still earn the fun swag!

*Youth-based pricing for the 5k/10k, 12 & Under are only $22!

• 5k/10k/15k registration includes a custom bib, designer shirt, and an awesome finisher medal!

• 1 Mile registration is untimed and includes a custom bib, designer shirt, and an awesome finisher medal!

• The kid's dash is a fun, untimed dash for our kiddos ages 10 and under. Registration includes a mini bib, youth-sized shirt, and a specifically crafted medal for our kids' dash event! (If your child wants to run the kid's dash, and doesn't want the SWAG, they are welcome to run with us on race day for free!)

*Register by midnight on Thursday, two Thursdays before race day, to guarantee your shirt!