Best places to swim near Boulder

Boulder looks like it should be full of swimming holes. It sits under the mountains, there's water in every direction, and on a 95-degree afternoon every pond you drive past looks inviting. The reality is narrower, and it's worth knowing before you pack a towel: most of the water you can see around Boulder is drinking-water storage, protected wildlife habitat, or both, and swimming in it is prohibited.

So this page is organized around what you're actually allowed to do. First, where you can swim. Then, where you can't, and why, because these rules surprise people and a couple of them carry a summons. Last, tubing Boulder Creek, which is the other classic way to get in the water here and comes with real safety strings attached. Every rule below is pulled from our own guide for that place, and each guide cites the agency that set it.

Swimming near Boulder at a glance

Every place below links to its own guide, where the fees, seasons, hours, and dog rules live. Rules do change, so check the guide and the managing agency before you go.

Where you can swim near Boulder

There's one open-water answer, and it's Boulder Reservoir. The city runs a sandy, lifeguarded swim beach there on the north side of town, and it's the only place in this roundup we'd send you to swim.

• Boulder Reservoir: The one true swim beach near town. Swimming is allowed only inside the marked area and only while lifeguards are on duty, and a day-use entry fee applies through the warm months.

The details that trip people up: swimming is allowed only in the designated swim area, and only while lifeguards are on duty, generally 10 a.m. to 6 p.m. daily from Memorial Day weekend through Labor Day. Swimming anywhere outside the marked area is prohibited, so you can't strike out across the lake. A daily entry fee is charged April 1 through October 31, and everyone pays, including people who walk or cycle in. The beach can also close temporarily for algae blooms, so it's worth checking the day's status before you drive out. Dogs are the other catch: they're prohibited through the gates and along the south shoreline from May 15 through Labor Day.

If you want water that's lifeguarded and predictable, the City of Boulder also runs two seasonal outdoor pools, Scott Carpenter Pool on 30th Street and Spruce Pool downtown. On a weekend when the reservoir lot is full by 9 a.m., that's not a consolation prize.

Where you can't swim, and why

This is the part that catches visitors, and honestly a lot of locals too. Swimming is not allowed in any City of Boulder Open Space and Mountain Parks body of water. That's a blanket rule, and it covers the lakes and ponds you walk past on the OSMP trails. The county draws the same line on its own land: Boulder County prohibits swimming and wading in all of its Parks and Open Space areas.

• Coot Lake: No designated swim area for people. The city doesn't designate or lifeguard a swim area here. The only swimming it describes at Coot Lake is for dogs, on the east and south shores. Boats, belly boats, and rafts are prohibited, and the city says anyone with a watercraft or a flotation device around Coot Lake will be issued a summons.
• Sawhill Ponds: No. Swimming and wading are prohibited. OSMP prohibits swimming and boats here, and that covers kayaks, carry-on boats, other watercraft, inner tubes, and wading. The one exception is a float tube used for fishing.
• Walden Ponds: No. Swimming and wading are prohibited. Boulder County prohibits swimming and wading in all of its Parks and Open Space areas, and Walden Ponds is specifically signed for no swimming and no boating.
• Wonderland Lake: No. Swimming and wading are prohibited. Swimming isn't allowed in any OSMP body of water, and wading into the lake is specifically prohibited at Wonderland. Boats and flotation devices aren't allowed either. Fishing is the water activity here.
• Teller Lake: No. Fishing only. Teller Farm's trailheads are listed by OSMP as fishing access, under state fishing regulations. Swimming isn't allowed in any OSMP lake or pond.
• Gross Reservoir: No. Body contact with the water isn't permitted. Swimming, wading, and cliff jumping are all prohibited, and pets aren't allowed in the water either. It's a fishing and non-motorized paddling reservoir. A dam-raise project also has the south side closed through 2027.

A few of these deserve a closer look, because "no swimming" doesn't always mean what people assume.

Sawhill Ponds and Walden Ponds: no swimming, no wading

These two sit next to each other east of town, they look nearly identical, and they're run by different agencies with the same answer on water. At Sawhill Ponds, OSMP prohibits swimming and boats, and that prohibition explicitly includes kayaks, carry-on boats, other watercraft, inner tubes, and wading. The only exception is a float tube used for fishing, which OSMP defines as a belly boat or kick boat that suspends one person from the seat down and isn't propelled by oars, paddles, or motors. At Walden Ponds, Boulder County's county-wide rule against swimming and wading applies, and the property is specifically signed for no swimming and no boating. Boats, float tubes, and ice fishing are all prohibited there.

The reason is the whole point of both properties: they're reclaimed gravel pits turned into wildlife habitat, full of nesting and resting waterfowl. People in the water is exactly what that habitat can't absorb.

Coot Lake: dogs can swim, people don't have a swim area

Coot Lake has a reputation as Boulder's dog beach, and that part is real, with limits. The city allows dogs to swim on the east and south shores only, and not on the west side or in any of the wetland areas, and dogs can be off leash only if they're registered in the Voice and Sight Tag Program. For people, though, there's no designated or lifeguarded swim area at Coot Lake at all, and the only swimming the city describes there is the dogs'. Boating, belly boats, and rafts are prohibited, and the city goes further: anyone with a watercraft or a flotation device around Coot Lake will be issued a summons with a potential fine. Part of the west side is also closed inside the wooden fence from March 15 through Sept. 10 every year for nesting birds.

Gross Reservoir: no body contact with the water

Gross Reservoir is Denver Water's, not the city's, and the rule there is the strictest on this page: body contact with the water is not permitted. Swimming, wading, and cliff jumping are all prohibited, and pets aren't allowed in the water either. What you can do is fish and paddle a non-motorized car-top boat in season. Note as well that Denver Water is raising Gross Dam through 2027, so the south side is closed and recreation has shifted to the free North Shore area, with blasting able to close parts of the reservoir on short notice.

Wonderland Lake and Teller Lake: fishing, not swimming

Wonderland Lake in north Boulder is a lovely flat loop and a good spot to fish with kids, but there's no swimming, and wading into the lake is specifically prohibited. Boats and flotation devices aren't allowed either. Out east, the Teller Lake water at Teller Farm is listed by OSMP as fishing access under state regulations, and the same OSMP-wide no-swimming rule applies. Anglers 16 and over need a valid Colorado Parks and Wildlife license at both.

Tubing Boulder Creek

The other classic way to get in the water here isn't swimming at all. It's floating Boulder Creek on a tube, straight through the middle of town. The usual put-in is Eben G. Fine Park at the mouth of Boulder Canyon, on the west edge of downtown, and tubers drift east alongside the Boulder Creek Path. Some people put in farther down near the Boulder Public Library for a gentler ride. The season generally runs from late May through early September.

Here's the part that matters more than the fun part. Boulder Creek is snowmelt, which means two things at once: it's cold enough to take your breath away even in August, and in late spring and early summer it runs high, fast, and genuinely dangerous. People get hurt on this creek. Tubing is a flow-dependent activity, not a date on the calendar, and it isn't recommended when the water is running high.

What the City of Boulder asks of tubers, and what we'd repeat to anyone:

• Check the water level first. Early-summer runoff can make the creek fast and pushy, and by late summer it can drop too low to float at all. Flow decides whether it's a good day.
• Wear a personal flotation device. Cold water saps strength fast, and a life jacket does the work when you can't.
• Wear sturdy water shoes. The creek bed is rocky, and the run includes real chutes, not just lazy pools.
• Put in below the whitewater park. The whitewater park just west of Eben G. Fine Park has rapids that aren't meant for tubes.
• Respect a closure. The Boulder County Sheriff can close the creek to tubing when it's unsafe. If it's closed, it's closed.

A helmet is worth thinking about too. It isn't a posted requirement we can point to, but the same rocks that call for water shoes are the ones your head meets if a tube flips in a chute, and plenty of experienced local floaters wear one at higher flows.

Two things to watch all summer

Algae. The City of Boulder posts warnings for its lakes and ponds because some blooms contain cyanobacteria, often called blue-green algae, which can produce toxins harmful to dogs and people at elevated levels. If you see algae, keep everyone out of the water, dogs included. The reservoir swim beach can close temporarily for a bloom, so check the day's status rather than assuming.

Cold. Mountain water near Boulder stays cold through the summer, and the alpine lakes up the canyons are colder still. Our roundup of the best lakes near Boulder covers the high country, where the answer on swimming is usually the same as it is down here: look, don't swim, and read the lake's own guide first.

Swimming near Boulder: FAQ

Sources and notes

This is a synthesis page. Every swimming, wading, boating, and tubing rule on it comes from our own full guide for that place, where it's sourced to the agency that set it: the City of Boulder (Parks and Recreation, and Open Space & Mountain Parks), Boulder County Parks & Open Space, Denver Water, and Colorado Parks and Wildlife. Fees, seasons, hours, and closures change, and creek flows change daily, so check the linked guide and the managing agency before you get in the water.

• Swimming and paddling in Boulder: the full activity hub, including paddling permits.
• Boulder Reservoir: swim beach hours, fees, watercraft permits, and dog rules.
• Boulder Creek Path: put-ins, access, parking, and the tubing season.
• Best lakes near Boulder: the alpine and in-town lakes, and what each one allows.
• Hiking with dogs in Boulder: how the Voice and Sight tag works, and where it doesn't.
• Thunderstorm safety in Boulder: why afternoon water plans go wrong here in summer.
• Things to do outdoors in Boulder: every activity on the site.