The hours are dusk to dawn. There's no fence that restricts access but the area is patrolled day and night, so if you're looking to stay much later than the dusk to dawn hours you'll need to call the parks department in advance. You can get a permit for night time photography and similar uses if you call them, but due to recent vandalism there and at other El Paso County locations, expect an issue if you're there significantly after dusk without prior authorization.
Dawn to dusk is the standard hours. Call El Paso county for extra permissions.
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