Swimming in Boulder is really two calendars stacked on top of each other. From roughly Memorial Day through Labor Day the city opens its outdoor water and the reservoir, and lap swimmers spread out across 50 meters of sunlit lanes. The rest of the year — which is most of the year at 5,300 feet — everything funnels into a small number of indoor lanes, one stubbornly heated outdoor pool, and whatever masters practice you can get to before work. Knowing which pools are actually open in any given month matters more here than in cities where the water never moves indoors.
It also helps to know how access works before you show up with a towel. Some facilities take walk-in drop-ins at a posted counter rate. Others are reservation-only and will not let you on deck without a booking. Masters clubs sell punch cards and monthly memberships that ride on top of whatever the host pool charges. And Boulder’s pools go down for maintenance more often than swimmers would like — as of early September, the North Boulder lap pool is still in an extended shutdown. Here is where the water is, who runs it, and what each option actually costs.
The City’s Indoor Pools Carry the Winter
City of Boulder Aquatics runs three indoor pools, and they are the backbone of the off-season. The North Boulder Recreation Center at 3170 Broadway holds a 25-yard, eight-lane pool kept around 82 degrees, plus a leisure pool, hot tub and sauna, and normally runs 6 a.m. to 8:30 p.m. weekdays and 7 a.m. to 5:30 p.m. weekends. The East Boulder Community Center at 5660 Sioux Drive has a 25-yard indoor pool that sits closer to 80 degrees. The South Boulder Recreation Center at 1360 Gillaspie Drive rounds out the three. Adult drop-in at a recreation center is $15 for ages 18 to 59, $11 at 60 and up, and $9 for youth. One caveat right now: North Boulder’s lap pool and hot tub have been closed for extended maintenance since August 1, with a tentative return in October or November, so check the city’s schedule before you go. South Boulder takes a short annual maintenance shutdown at the end of August and is otherwise open.
Scott Carpenter Pool Is the Only 50-Meter Water in Town
Scott Carpenter Pool at 1505 30th Street is Boulder’s long-course option, and it is outdoor and seasonal only — closed through fall and winter. It converts between configurations during the season: the short-course 25-yard setup is in place from opening through Memorial Day, again on Fridays, Saturdays and Sundays through the summer, and from after Labor Day until the pool closes for the year. The rest of the time it swims as a 50-meter Olympic-length course, which is why distance and triathlon swimmers plan their spring and summer around it. For 2026 the long course has already come out and the pool is short-course only to a September 20 season close. Outdoor pool drop-in runs $15 for adults, $12 for older adults and $11 for youth. Spruce Pool at 2102 Spruce Street is the city’s other outdoor pool, and it runs a summer season only, closing for the year around Labor Day, so check the city’s pool schedules before building a week around either one.
Boulder Elks Pool Runs the Opposite Calendar
Boulder Elks Pool & Patio at 3975 28th Street is the answer to the question every transplant asks: can you swim outside here in February? Yes. The 25-meter, six-lane outdoor pool is heated to 82 degrees, and its reserved lap swimming and pool-running season runs mid-September through the end of May — precisely the window when the city’s outdoor pools are drained. It stays open in most weather and closes only when extreme cold or unexpected snow and ice make the deck unsafe. Access is by reservation only; there is no drop-in and no lifeguard, so swimmers are responsible for themselves. A single session is $12.50, a 12-swim pack is $130 and good for a year, and unlimited monthly access is $99 for non-members or $59 for Elks members. First swim is free. The pool nearly lost its winter in 2024, when a damaged boiler and a stalled insurance claim left the lodge renting temporary units at $14,000 a month; it stayed open after community pushback and a cost-sharing arrangement with a local swim club.
Boulder Aquatic Masters Follows the Pools Around Town
Boulder Aquatic Masters is a nonprofit U.S. Masters Swimming club for adults 18 and over, started in the 1990s as a partnership with the City of Boulder and now counting swimmers in the hundreds. What makes BAM useful is that it moves with the water: through early September the club is running workouts at the Elks pool, East Boulder and Scott Carpenter, and it shifts to the indoor pools and the Elks as the outdoor pools drain. Check the club’s booking schedule for current workout locations. Its workout listings use a star system that flags both intensity and how crowded a lane is likely to be, which is a small thing that saves a lot of frustration at 5:45 a.m. The club carries U.S. Masters Swimming’s Certified Coach designation, and it takes questions at coaching@bamswimming.org. In summer, BAM holds open-water sessions at the reservoir Tuesdays and Thursdays from 6:30 to 7:40 a.m.
Elevation Athletics Moved Its Winter Indoors
Elevation Athletics started in 2018 and runs both a USA Swimming youth program and a U.S. Masters Swimming Gold Club team for swimmers 18 and up, along with lessons for ages 5 and older, clinics and lifeguard certification. The group trains across most of the water in the county — the three city recreation centers, Scott Carpenter, Spruce, the Louisville rec center and the CU Boulder competition pool — which is how it has absorbed years of rotating closures. Through Scott Carpenter’s September 20 closing the masters group trains there most days, then moves to the indoor pools for the winter. Masters pricing is listed at $100 a month all-access, or punch cards in 1, 10, 15 and 20-punch tiers running $17 to $250, and masters swimmers are required to hold U.S. Masters Swimming membership. Masters coaching is led by Karina Plocek and Chris Lipson under owner-director Eric Stefanski. Elevation Athletics says it is planning and fundraising to build a new 50-meter pool in the area, with tax-deductible donations going through the Colorado Youth Athletics Foundation.
Louisville’s Rec Center Is the Overflow Plan
When Boulder’s indoor lanes go down for maintenance, a lot of swimmers drive 20 minutes southeast. The Louisville Recreation & Senior Center at 900 West Via Appia keeps a six-lane, 25-meter lap pool plus a separate four-lane, 25-yard program pool used for lessons and team training — meaning lap swimmers are less likely to be squeezed out when a class takes the water. There is also a lazy river and slide, a splash pool for small kids, and a recovery block of sauna, steam room, hot tub and cold plunge. It is a genuine Boulder County option rather than a Denver-metro one, and it stays open year-round.
Open Water: Boulder Reservoir and Union Reservoir
The Boulder Reservoir swim area runs Memorial Day through Labor Day, generally 10 a.m. to 6 p.m., closing at 5:30 on Thursdays for the Stroke & Stride race series. The city won’t open the shallow area below 60 degrees or the full area below 64, and there is a temperature line at 303-441-3461 worth calling before you load the car. Swimming is confined to the lifeguarded area, kids under 13 need a lifeguard-administered swim test for deep water, and drop-in is $12 per person, $20 for two people in one vehicle, or $30 for a carload of five.
North of there, Union Reservoir in Longmont had a complicated 2026: low water meant the full swim beach did not open, replaced by a wading area no deeper than three feet from May 23 to September 19, at swimmers’ own risk. But the city added a supervised open-water swim program for ages 16 and up that ran June 2 through August 15 — Tuesdays and Wednesdays 6:15 to 7:30 p.m. and Saturdays 8:30 to 9:45 a.m., $10 per person with pre-registration required and certified lifeguards on duty. Vehicle entry is $10 on weekdays and $15 on summer weekends, or $2 to walk or bike in. Water access closes entirely from December 1 through the end of February.
Before You Drive Over
Three habits will save you a wasted trip. Check the schedule the morning of, not the week before — Boulder’s pool pages carry the warning that schedules can change with little or no notice, and the city offers text alerts for unplanned closures. Sort out whether your pool takes drop-ins or requires a reservation; the Elks pool, for one, is reservation-only. And build in a week of adjustment for the altitude: swimmers who arrive from sea level routinely find their usual interval unsustainable for the first several sessions, which is a physiology problem, not a fitness one. If you’re new in town and want company for that, both masters clubs let you try a workout before committing.
Featured image: “Lap Swim” by ashleigh290 — CC BY 2.0 (https://creativecommons.org/licenses/by/2.0/). Source: https://www.flickr.com/photos/16440393@N04/2779666605
