OverviewDouglas County is just south and east of Jefferson County, and has a large amount of Open Space, but very little of it is currently open and accessible to the public. Much of it is still in private leases for ranching, etc. They do, however, have a few parks open, and it seems like they are in the process of getting many more open and ready for use.
Getting ThereFrom Denver, drive south on I-25 for about 30 miles until you reach the county line. From Jefferson County, drive C-470 south/east until you cross the South Platte River, which is the boundary between Jefferson County and Douglas County.
Red TapeOnly a few parks are currently open and available, but it seems like many are on the near horizon. No other red tape.
External LinksDouglas County Open Space web page.
Complete list of trails HERE.