The best and easiest access to the Medano Lake Trail is from the east side of Medano Pass. To get there, make your way to either Westcliffe or Walsenburg. From Westcliffe, drive south on CO 69 for 24.7 miles (mileages may vary) to a marked turnoff on the west side of the highway for Medano Pass.
From I-25 north of Walsenburg, take exit #52 west and turn onto SH69 that goes to Gardner. Begin measuring where the highway in Gardner makes a jog to the south, then back west. Continue following CO 69 for 9.4 miles NW to the same signed turnoff as coming from Westcliffe.
For both accesses, proceed west on CR 559 which will head generally WNW past Creager Reservoir, then turn more to the west to begin the climb to Medano Pass. At 7.5 miles from CO 69, CR 559 will come to an area of multiple roads turning off including FR 412. Stay on what will now be FR 559 to Medano Pass, another 1.8 miles. These last two miles are the only part that require 4WD and in 2004 we did not find it either slow or difficult to drive. The only problems were some potholes. From the wooded summit of the low pass, continue SW for .6 mile to an intersection. Turn right and drive a short distance to the trailhead. There are a couple campsites with firerings but without facilities here. Bear boxes are provided. You are now in the Great Sand Dunes National Park. No permit is required to camp in this location as of 2018. We'll call this the "Medano Pass/Creek Campsite."
The main road continues on out to the park visitor center and main campground, several slow miles away. When you are done with your hike/climb, if you want to continue driving this road, be advised of the following: 1. There are some "backcountry campsites" along the way that a permit may be required for. 2. The road initially goes fairly speedily, but you'll soon encounter rocky stretches that will slow progress considerably. 3. Farther down the road, as it begins to come near the sand dunes, it will become quite sandy and tricky to drive, especially with some vehicles approaching from the other direction. You'll want to keep your vehicle moving whenever and wherever possible as stopping may prove to make it difficult to get moving again in the sand. At times, this lower section of road becomes impassable, either because of the sand or because Medano Creek is flowing high. You should not attempt to drive this without checking with the park first. If driving this road north from the park entrance and the visitor center, you will cross Medano Creek 8 times. In the high runoff part of the season, a couple of the crossing may be impossible to make because the water is so high. Therefore, if driving to the trailhead from this direction, it is definitley best to wait until the runoff has subsided. Go to the park website at: https://www.nps.gov/grsa/index.htm for more information or call the headquarters at 719-378-6395.
If coming from the north end of the San Luis Valley on US 285, follow US 285 south to Poncha Pass from Poncha Springs, and continue south to Villa Grove. Five miles south of Villa Grove, turn off to the left onto SH17, which is the more direct route to Alamosa. It's 30 miles to Hooper (you may nearly miss this little town) and from Hooper, continue south another 6 miles to County Road 6N where you will turn left (east). Drive 16.4 miles east to where 6N intersects with SH150. Make a left and drive to the Great Sand Dunes National Park entrance.