Thomas Reservoir is a small neighborhood lake near Erie in Boulder County that punches above its weight as a go-to spot for walking, fishing, and watching Colorado wildlife. Located at 119th Street and Austin Avenue, this municipally managed reservoir features a 0.66-mile gravel loop trail that locals circle two or three times for a quick two-mile walk, often with dogs in tow and fishing rods at the ready. If you live anywhere between Boulder, Broomfield, and Longmont, Thomas Reservoir is one of those reliable little spots you return to again and again.
Fishing is a favorite activity at Thomas Reservoir, especially for families with children. The lake holds largemouth bass, bluegill, channel catfish, and perch, with trout stocked periodically. Bait fishing with worms and PowerBait produces consistent results, and spinners work well for bass and bluegill. Multiple reviewers mention catching impressive numbers of fish in a single outing, making this an ideal spot to introduce kids to fishing. A valid Colorado fishing license is required for anglers 16 and older.
The 0.66-mile gravel path circling the reservoir is flat, accessible, and open year-round during daylight hours. Dog walkers, joggers, families with strollers, and birders share the trail in a friendly, low-key atmosphere. The loop offers views of the surrounding Front Range and, on the right morning, you might catch hot air balloons launching beyond the lake with their reflections shimmering on the water. Bald eagles, hawks, and various waterfowl are spotted regularly, and the reservoir is designated as part of the Colorado Birding Trail.
Thomas Reservoir has picnic areas near the parking lot on the south side of Austin Avenue, just east of 119th Street. The trail and parking are ADA accessible. No swimming or boating is permitted. A portable toilet is available on site, though reviewers note it could use more frequent servicing. The surrounding neighborhood is quiet and residential, so visitors should be mindful of parking restrictions and noise.
The reservoir shines in every season. Spring and fall bring the best fishing temperatures and active wildlife. Summer evenings are perfect for a sunset walk around the loop. Winter draws birders scanning for gulls on the partially frozen water. Thomas Reservoir may not be a destination lake, but for the communities around Erie and Boulder County, it is a dependable slice of Colorado outdoor life just minutes from home.