Boulder Reservoir Loop, Boulder Reservoir, Boulder - Denver - Golden - Fort Collins - Lyons, Colorado

Boulder Reservoir Loop - 5.25 miles

Boulder Reservoir

The Boulder Reservoir

The Boulder Reservoir

Round-Trip Length: 5.25 miles
Start-End Elevation: 5,260' - 5,260' (5,383' max elevation)
Elevation Change: +123' net elevation gain (+210' total roundtrip elevation gain)
Skill Level: Easy
Dogs Allowed: Yes
Bikes Allowed: Yes
Horses Allowed: No
Related Trails:

Boulder Reservoir Loop - 5.25 Miles Round-Trip

The Boulder Reservoir is a 700-acre multi-use recreation area and water-storage unit. It's surrounded by short grass prairie and wetlands framed by the Boulder foothills. The Boulder Reservoir supplies 20% of Boulder's drinking water, 80-90% of which comes from the Boulder Feeder Canal and 10-20% from seasonal creeks and ditches.

Trail Map | Photo Gallery

It typically fills by June and draws down to half its 13,270 acre-feet capacity by September. The facility includes beach volleyball courts, boat rentals, a seasonal swim beach, restrooms, showers, horseshoe pits, 13 picnic tables and ramp access for boats.

A series of paved, dirt and gravel road-trails form a contiguous 5.25 mile loop around the reservoir, deservedly one of Boulder's most popular running, cycling and bird watching destinations. Connections with the Eagle Trail and Coot Lake extend routing options through this biologically rich area.

There are four access points to the Boulder Reservoir Loop - the following description begins at the 51st Street - West Portal Entrance and travels clockwise:

The trail begins on a rolling, graded dirt road with one steep hill to the Eagle Trailhead lot (.8 miles : 5,258').

Sunflowers and thistle line this section, an area busy with prairie dogs, snakes, rabbit, coyote and raptors. The road continues northeast through wetlands (east) and open space (west) up to the 55th Street Trailhead (1.75 miles : 5,232').

Enter the lot and bear east on a narrow gravel path set just above the reservoir. Look for osprey, herons, egrets, ducks and pelicans in the nearby marsh. The trail steepens (2.1 miles) on a short switchback that levels over the main canal (2.35 miles : 5,245').

It widens on a dirt road with three access points to Coot Lake before curling west (2.9 miles : 5,228') to the reservoir's North Dam.

Here it turns sharply south (3.25 miles : 5,220') along the flat dam wall, a fast-moving section with panoramas across the reservoir, foothills and back range. The road-trail turns southwest over the South Dam wall (3.85 miles : 5,222'), another fast section with comparable views.

It merges with a hilly paved road on the reservoir's south shore (4.45 miles : 5,234') that rolls past the marina, boat house and swimming beach to complete the loop at the West Portal Entrance Station (5.25 miles).

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Interactive GPS Topo Map

Key GPS Coordinates - DATUM WGS84

  • N40 04.290 W105 14.094 — 0.0 miles : Boulder Reservoir - West Portal Trailhead
  • N40 04.814 W105 14.113 — .8 miles : Eagle Trailhead
  • N40 05.234 W105 13.578 — 1.75 miles : 55th Street Trailhead
  • N40 05.178 W105 13.053 — 2.35 miles : Cross over canal
  • N40 05.068 W105 12.652 — 3.25 miles : Begin travel over north dam
  • N40 04.590 W105 12.741 — 3.85 miles : Begin travel over south dam
  • N40 04.218 W105 13.192 — 4.45 miles : Begin paved travel on south shore
  • N40 04.290 W105 14.094 — 5.25 miles : West Portal Trailhead

Worth Noting

  • There is little shade on the Boulder Reservoir Loop; sun protection is recommended year round. Expect strong winds, especially in the spring.

  • A food-snack concession is located in the main building above the swimming beach. The concession is open during beach hours between Memorial Day and Labor Day. There are also restrooms, showers and changing facilities.

  • Miles of connecting roads, swimmable waters and adjacent acreage make the Boulder Reservoir an ideal host for athletic events such as The Canine Classic, Title 9 Sports, CWW Mini Triathlon, CWW Swim, 5430 Sprint Triathlon, 5430 Boulder Peak Triathlon, Boulder Kids Triathlon, Boulder Trail Triathlon, Boulder Marathon and Annual Polar Bear Plunge.

Fishing Information

  • Fishing is permitted with a valid Colorado fishing license. Fishing guidelines for the Boulder Reservoir can be found on the Colorado DOW website. Visitors are responsible for knowing applicable laws. The reservoir is regularly patrolled and laws are strictly enforced.

  • Species (2009 survey): Walleye, Smallmouth Bass, Channel Catfish, Crappie, Yellow Perch, Bluegill, Gizzard Shad, Common Carp, Green Sunfish, Largemouth Bass and White Sucker.

  • All watercraft including canoes, kayaks, wind and kite-surfers require a valid Boulder Reservoir boating permit. Permits are available at the reservoir during regular business hours. All boaters are responsible for knowing and obeying applicable laws.

  • Watercraft permits are available at the boat house for $10 per craft. Water craft may only be launched from the south shore of the reservoir (within the front gate). Kayaks, belly boats or other water craft may no longer be launched from the north shore of the reservoir to ensure compliance with reservoir policies regarding proper cleaning and disinfecting of vessels.

  • To prevent the introduction of aquatic nuisance species and improve boater safety, the sale of one-day power boating permits has been suspended until adequate standards to prevent the spread of aquatic nuisance species by day-use boaters can be developed.

Rules and Regulations

Operating Hours

  • Monday - Friday 6:30 am - 4 pm for incoming traffic, 6:30 am - 4 pm for outgoing traffic.

  • Saturday and Sunday 10 a.m. to 4 p.m. for incoming traffic, 10 am to 4 pm for outgoing traffic.

Fees (collected for each person entering the reservoir including runners, walkers and cyclists)

  • Adult: $7

  • Child (3-12): $4

  • Teen: (13-18): $4

  • Senior (60+): $5

  • Call 303.441.3461 for season pass information

Dogs, Horses, Camping

  • Dogs are allowed outside the south shore area on established trails and roads year round. Dogs are not allowed through the gates or anywhere along the south shore May 15 - Labor Day. Dogs are permitted on the south shore Labor Day - May 14. Leash laws apply.

  • Horses are not permitted at the Boulder Reservoir.

  • Camping is not permitted at the Boulder Reservoir.

  • Fires, personal charcoal and wood burning grills are prohibited. Glass containers and bottles are prohibited.

Beach Hours and Swimming:

  • Swimming is permitted only within designated areas while lifeguards are on duty. Groups of 10 or more require a reservation to ensure staffing levels are adequate.

  • Open-water swim permits are available Wednesday mornings at 7am for $10.

  • May 26 - Sept. 5 daily, 9 am - 7 pm (the beach will close Thursdays at 5:45 pm for Stroke and Stride events).

  • Sept. 6 - 21 weekends only, 9 am -7 pm.

Directions to Trailhead

The Boulder Reservoir is located on 51st street in Boulder, Colorado.

The West Portal Entrance is located 1.45 miles north of Jay Road. The turnoff for 51st street from Jay Road is located 1.3 miles east of Highway 36, or .1 miles west from the Diagonal Highway exit.

Contact Information

Boulder Reservoir
General Information and Front Gate: 303.441.3461
Reservoir Fax Line: 303.441.1807

Boat House and Boat Rentals: 303.441.3468
Sports, Events and Rainout information: 303.441.3410

Reservoir Manager: 303.413.7278
Reservoir Programmer: 303.441.1806

Boulder Parks and Recreation
3198 Broadway
Boulder, CO 80302

Trip Reports

There are no trip reports on this trail.


"Just so others know, except for the North side the entire loop is on the road. There is no trail inside the park, so you have to run on/next to the road. And the entrance fees have gone up, Adults are $7, Kids are $4 and Seniors are $5 to get in. They only charge from Memorial day to Labor day. "
Colorado  -   -  Date Posted: January 11, 2017
"The rattlesnakes are out! Just hopped over one today on the Eagle Trail near the main Reservoir Loop. Stay alert, especially on singletrack and through areas of tall grass. "
ProTrails Admin  -   -  Date Posted: April 29, 2015
"Watercraft permits are $40 per small watercraft, not $10"
Jen M  -  United States  -  Date Posted: October 22, 2014
"Dogs are not allowed inside the boulder reservoir while in season, so most of the summer. "
katie  -   -  Date Posted: June 6, 2014


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