I found this on www.coloradotrail.org under FAQ
Q. How do you get from Denver International Airport to the start of The Colorado Trail at Waterton Canyon?
A. How to Get from the Denver Airport to the Beginning of The Colorado Trail
Transportation from Denver International Airport to the CT is not an insignificant problem. They are located on opposite sides of the Denver metropolitan area which is a distance of about 60 miles. The Yellow Cab Company (303-777-7777) quoted a price of $70 in April of 2001.
The local bus/light rail system will take you from the Airport to the Littleton/Mineral Ave. terminal, the closest one to the beginning of the CT which is both bad news and good news. The bad news is it is still almost 10 miles to the beginning of the CT. The good news is that there is a hiking/biking trail starting at the terminal that leads to the CT. The “AT” bus leaves the Airport for the Littleton terminal every hour from early morning to late evening. The ride takes about an hour and a half. If you wish to go via downtown Denver for some reason the Skyride bus leaves the airport every few minutes for central Denver. From central Denver you would catch the light rail route 101 also known as the Southwest/Central line to the Littleton terminal. It runs every 10 to 15 minutes from central Denver. The Yellow Cab Company quotes $60 from the Littleton terminal to the CT trailhead, a distance of 9 miles.
It is approximately 9 miles (one hour by bike) to get from the Littleton/Mineral Ave. terminal to the CT parking lot. Waterton Canyon is visible in the distance when looking in a southwest direction. You will take the bike path and then a two-track dirt road around the west side of Chatfield State Park to reach the trailhead. >From the rail station, proceed west on Mineral Ave. for ¼ mile where the sidewalk turns into the hiking/biking trail in the South Platte Park. Cross over the South Platte on the bridge and head upstream (south). You will cross under Mineral Ave. and then in approximately a mile you will cross under the highway. >From this point, proceed west and follow the bike path and signs to Chatfield State Park. After cresting the dam, proceed southwest on the bike path until you reach the main park entrance road and fee station. Immediately past the fee station, exit the bike path and walk/ride to the south along the main park loop road (parallel to the Lake). Beware - Do not proceed on the bike path on the east side of the road or you will have a lengthy detour. Instead, proceed south/southwest on the main loop road for approximately 1/2 mile until you reach an intersection signed “B&B Livery - Horse Rental.” Take this road southwest and uphill for another half mile until you reach the public corral. At the corral, look to the west for a two track dirt road marked with brown carsonite posts with blue and white arrows. Proceed on this road following the signs until you reach the trailhead.
Chatfield State Park only allows camping in designated areas. Unfortunately these areas are all on the other side of the lake. There are however several nice areas where a tired hiker could settle down and “nap” for a while. The best areas are near the Mineral Ave. Station along the river and areas very close to the trailhead itself. Camping is not permitted along first 6.2 miles of the CT since that is the service road for the Strontia Springs dam. Bear Creek, 8 miles from the beginning of the CT, is the first camping spot with water.
The Lockheed Martin Discovery Pavilion provides a place to stop and rest and information about the three major trails in the area. It forms the connecting link from the metro area through Chatfield State Park to The Colorado Trail.
There are public telephones at the Littleton Park-N-Ride, the Chatfield camping area, and the Waterton Canyon parking lot. Restrooms and drinking water are available at the Theo Carson Nature Center (in South Platte Park), at several locations in Chatfield State Recreation Area, and near the Discovery Pavilion.
RTD: www.RTD.Denver.com
1-800-366RIDE
Jeff Kinsel