Castlewood Canyon State Park

Castlewood Canyon State Park is built around the sandstone canyon Cherry Creek carved into the Palmer Divide on its way to Denver. The geology is the surface story; the better story is the 90-year-old ruins on the canyon floor.

Castlewood Canyon Dam was built across Cherry Creek in 1890 to irrigate farmland on the High Plains. The structure was 600 feet long and 70 feet high, masonry and local rock-fill, 8 feet wide at the crest and 50 feet at the base. It started seeping the day it filled and it never stopped. For 43 years the dam leaked, the cracks widened, and Denver lived downstream of a structure that almost everyone in the engineering community considered a bad idea. Then on August 3, 1933, a Palmer Divide cloudburst pushed the reservoir over the top, and at roughly 1 a.m. the dam gave way. More than a billion gallons of water came down Cherry Creek as an 11-foot wall, hit downtown Denver about three hours later, killed two people, and caused around $1M in damage (~$20M in current dollars). Roughly 5,000 people evacuated in time, mostly because Nettie Driskill, working the overnight switchboard at the local exchange, phoned house after house down the creek with one line: hurry to higher ground. The 1933 disaster is the direct reason the modern Cherry Creek Dam (the one that holds back Cherry Creek Reservoir at Cherry Creek State Park) exists. Walk the Inner Canyon Loop and you walk past the ruins of the original. Most of the dam collapsed. The south abutment and a section of the spillway are still standing, weathered and interpretive-signed.

The signature hike is the Inner Canyon Loop, 2.5 miles and 300 feet of elevation, which takes you along the creek, past the dam ruins, and up one side of the rim. String it together with the Rim Rock Trail and you have a 5-mile day with real vertical and the Pikes Peak panorama. Trail surface is mostly good crushed gravel and packed dirt, well maintained, draining properly even after the August thunderstorms.

The South Entrance off Highway 83 is the one we use. The main North entrance (off Castlewood Canyon Road near Franktown) gets the weekend traffic and fills its lot by 9:30 a.m. from May through October. The South side has roughly half the parking and half the crowds.

$11 per-vehicle day pass, or the $84 Colorado Parks Pass if you'll go more than eight times a year. Dogs leashed, no grills outside designated picnic areas, no drone flying.