Oliver Turner, an English Channel swimmer and a 3-time Manhattan Island Marathon Swim finisher, founded the Horsetooth Open Water Swim in 1999.  While he was a graduate student at Colorado State University, he came up with the idea of a long distance swim that would challenge the swimmers and also be a fundraiser for the Wingshadow Foundation. His vision had the swimmers navigate the length of the reservoir (~10 km) where in alternating years it would be swum either north to south or south to north. The first year, there were 15 brave souls that swam the reservoir north to south.

A four-year dam repair and strengthening project began in 2000 that virtually drained the reservoir. This caused the swim to be temporarily moved to nearby Carter Lake in 2000 where a 4.8-mile out-and-back course was implemented.

In 2001, an alternate out-and-back 10 km course was identified in Horsetooth Reservoir.  Starting about midway, at the Sail and Saddle Club, swimmers went to the north end and back.

In its drained state,  Horsetooth Reservoir resembled two bodies of water with a channel between them that the swimmers needed to swim through.  In 2002, a weird situation occurred where the southernmost section was  16°C (60°F) while the northernmost  section was 21°C (70°F). The swimming from cold water into warm water and then back into cold water proved to be unique and particularly challenging to quite a few swimmers.

In 2003 the 2.4 and 1.2 mile swims were added. By 2004, Horsetooth Reservoir dam rework was complete and the swim was able to return to the original format of swimming the full length of the lake. The number of participants grew and with the addition of the shorter races, the direction of the swim changed.   Swimmers started at the south end and swam  north to finish in Satanka Cove.

In 2006, several exciting things happened with the race. First, the Horsetooth Swim 10K was awarded the U.S. Masters Swimming Long Distance Open Water Championship for the 6+ mile distance.  It also was the first year of youth (age group )(1000 yard, 250 yard) swims.

In 2007, with the closing of the Wingshadow Foundation, the beneficiary changed to Team Wellness and Prevention whose mission is promoting healthy lifestyles through the prevention of substance abuse.

In 2011, Larimer County Parks completed a beautiful pavilion at the South Bay beach area. This provided a perfect, beautiful venue for hosting the shorter races and the finish line for the 10 km marathon swim.  The 10 km swim changed back to north –  south swim. The side effect of this change is the South Bay beach area is short of the full length of the lake by about 500 m. Several approaches have been made to address this.

In 2011, the 10 km marathon swimmers swam past the finish line about 250 mm and then back in to add the distance. In 2012, the water level was extremely low due to a severe drought such that there was not enough lake past the finish line to make the full 10 km distance. The decision was made to just swim point-to-point the length of what was left of the lake, resulting in a distance of 9.4 km (5.85 miles). In 2013 the water level returned to a more normal level and the decision was made to direct the swimmers into a cove near the start to add distance to make a full 10 km marathon swim.

Some highlights and lowlights over the years:

1999:       Inaugural event!

2000:       Horsetooth dam reconstruction begun; swim held at Carter Lake.

2001:       Lucien Harkart, from Belgium, swims the 10k all breaststroke.

2002:       Water temp was in the mid-50s and several swimmers DNF with near hypothermia.

2003:       2.4 mile swim wet suit and non-wet suit events added to the race.

2004:       The “dam work” done, participation jumps dramatically.

2005:       Rain and fog on race morning, visibility so low paddlers can’t find swimmers.

2006:       Horsetooth Swim Open Water Swim was the USMS 10k National Championship.  Age group events added; these & 2.4 mile swims were held at Carter Lake.

2007:       Full slate of events at Horsetooth: 10k, 2.4 mile, 1 mile, 1000 yards, 250 yards

2008:       As close to normal year as we get at the Horsetooth Open Water Swim!

2009        Strong south/southeast wind made for good swimming and difficult paddling.

2010        Another successful year.  Some rough seas made the times a little slower.

2011        The new South Bay beach and pavilion are open, the 10k course returns to a north-to-south travel plan with the biggest field of swimmers ever.  The 2.4 and 1.2 mile, 1000 and 250 yard swims start and finish at the South Bay beach boat ramp.

2012:       Course not quite 10k due to drought-induced low water levels.  High Park Fire burn scars can be seen from the reservoir.

2013:       Joe Bakel swims the 10k all butterfly.  Course enters Soldier Canyon Cove to ensure full distance; quite a few collisions ensue.  Race start is delayed because Coast Guard boat won’t start.

2014:      Highest water level ever for the Horsetooth Swim at 99.9% full

2015:      Added the 1.2M wetsuit.  John Batchelder swims 10k all butterfly.

2016:     Kilometer maker buoys for the first time.

2017:     Moved swim to after Labor Day. Lowest water levels since 2003.


Horsetooth 10k Open Water Swim Winners

Year No. Finish/ No. Start Water Temp °F Male Winner Time Female Winner Time
1999 15/15 68 Norman Schultz 2:27:06 Erin O’Mara 2:47:37
2000 24/24 65 Eric Johnson 1:50:54a Laura Hansen 1:55:05a
2001 20/20 70 Joe Bakel 2:21:55b Laura (Hansen) Borgelt 2:19:50b
2002 18/23 < 60 Richard Pease 2:31:14b Laura Borgelt 2:33:58b
2003 22/24 68 Richard Pease 2:20:22b Voni Oerman 2:30:30b
2004 50/50 69 Todd Bryan 2:22:38 Bridgette Lacy 2:20:35
2005 48/48 68 Brooks Felton 2:11:13 Taylor Felton 2:35.29
2006 79/83 72 Brooks Felton 2:09:31 Alicia Kendig 2:27:09
2007 56/56 72 Todd Bryan 2:23:24 Alicia Kendig 2:27:15
2008 42/44 72 Thomas Taylor 2:29:40 Sarah Vincent 2:26:50
2009 70/70 70 Todd Bryan 2:16:54 Sarah (Vincent) Thomas 2:20:06
2010 63/64 73 NK Martin 2:30:40 Sarah Thomas 2:31:43
2011 80/86 73 Kurt Dickson 2:19:42 Shauna Nelson 2:18:23
2012 60/60 69 Kurt Dickson 2:11:16c Shauna Nelson 2:09:35c
2013 80/80 69 Kurt Dickson 2:20:00 Joy Stover 2:25:42
2014 64/64 72 Alon Mandel 2:19:52 Joy Stover 2:29:56
2015 74/79 70 Alon Mandel 2:17:14 Kristin Hultgren

(Astrid Itrube)d



2016 72/77 70 Daniel Hendricks 2:21:40 Kristen Hultgren 2:30:22
2017 73/76 68 Karl Kingery 2:25:56 Bailey Pons 2:30:00

a      Carter Lake, approximately 4.8 miles / 7.7 km

b     Out and back course from Sail and Saddle Club, approximately 6.2 miles / 10 km

c   Water level low, course estimated at 5.86 miles / 9.4 km

d   Exhibition swim