Gunlock State Park sits at 1450 South Gunlock Road in Gunlock, Utah, roughly 15 miles northwest of St. George on the Santa Clara River. Utah State Parks runs the 549-acre park, and the Washington County Water Conservancy District owns and operates the reservoir behind the 1970 dam. Gunlock Reservoir covers about 266 acres at 3,600 feet of elevation and holds 10,884 acre-feet when full. The park is open year round, 7 a.m. to 10 p.m. daily.

Check the algae advisory before you get in. The Utah Division of Water Quality has had a warning advisory posted on Gunlock Reservoir since August 17, 2026, when sampling confirmed a harmful algal bloom. The advisory tells visitors not to swim or water ski, to avoid visible algae while boating, to keep animals out, and to discard fish skin and guts. DWQ samples the reservoir for cyanotoxins and E. coli through the warm months and posts each result on its Gunlock Reservoir monitoring page. Bloom status shifts week to week, so read that page the morning you go instead of trusting last season's all clear.

Swimming happens off the sandy east shoreline near the boat ramp and campground. No lifeguards, no marked swim area, no roped shallows. Staff also flag floating debris that washes in after runoff. Every watercraft checks in at the entrance station and has to satisfy quagga mussel rules, and there is no decontamination station at Gunlock, so arrive already dried out or decontaminated somewhere else.

Gunlock Falls is the other draw and it is unreliable. Water only pours over the red sandstone spillway below the dam when the reservoir passes 105 percent of capacity. That happened in spring 2026 at 106 percent after storms and post-Forsyth Fire runoff, but the park lists the falls as not flowing once snowpack runs out, and many years produce nothing at all. The Falls Hike is a 1.2-mile out-and-back. The spillway is worth looking at and a bad place to get in the water: the plunge pools run two to three feet deep over hidden rock, the sandstone stays slick, and there are no barriers. Search and rescue crews answered more than a dozen calls there in 2023, including an 18-year-old who broke both legs jumping from the cliffs, and a cliff diver died at the falls in 2019.

Day-use costs $25 per vehicle for non-residents, $15 for Utah residents and $10 for Utah residents 65 and over, watercraft launching included. A Utah State Parks annual day-use pass is $125, or $65 for seniors. Camping is 30 hookup sites at $45 a night plus $20 for each extra vehicle, with cottages at $175 a night, all booked through ReserveAmerica. Cottages have a kitchenette, heating and air conditioning, a full bathroom, a picnic table and a fire ring, but you bring bedding and towels. Day-use facilities include restrooms, showers, picnic tables, grills, fire pits, shade shelters and group pavilions. Boat ramp hours run 7 a.m. to 8 p.m. May through September and 7 a.m. to 7 p.m. October through April. Fireworks are banned parkwide. Gunlock is a state Blue Ribbon fishery for largemouth bass, bluegill, black crappie and catfish, so anglers work the same shoreline. Park phone is 435-218-6544.