The Water Line Trail, or Water Line Road as it is also known, is the gravel access road that climbs the east slope of the San Francisco Peaks into the Inner Basin, and beyond. It is the main access to the water pumps which are used to procure water from the Inner Basin for Flagstaff's water supply. At some points along the road you come to square concrete "manholes" which have accesses to the water line that follows the road down to town, and gives the road its name. When the water is flowing, you can hear it in these manholes.
The Water Line Road has two parts, the maintained lower 2/3 and the rough upper 1/3. I have been on the lower 2/3 from Schultz Pass to the Inner Basin. It is smooth and while not much of a hike, is an excellent mountain biking opportunity. It is about 9 miles up, and you will gain about 1700 feet to that point. The lower 2/3 is graveled and is smooth enough that a car could be driven up it, yet because the road is gated, you likely won't see motor vehicles on it. This section of road will take you to the first pump house in the Inner Basin, and the trail of that name. At that point you will encounter a faucet which is a source of water when the pumps are on. Its not filtered, but it is great for dogs, and you if you have a hearty stomach. At this point you can continue on into the Inner Basin to just past the 3rd structure that you will encounter. For a full description of this, see the Inner Basin trail. This watering area is also where you may be able to continue on further on the upper 1/3 of the road. Good luck if you choose to do so. I have never been more than 200 feet up on the upper portion, if I was even that far. I continued up a road that logically should have been it, but I'm not sure. If it wasn't the upper part, then I have no idea where this road goes. The road isn't maintained past its meeting with the Inner Basin trail, it was badly eroded and it had some downed trees across it. I turned back. This might be a more interesting hike, but on a bike its not really worth doing. Plus, its more fun to go into the basin and look at the peaks. Heading down the Water Line Trail is a lot of fun, and it goes rather quickly. Be safe and try not to let your speed get away from you.
The Water Line Road is part of the boundary of the Kachina Peaks Wilderness Area. Before you get into the Inner Basin everything past the gas line and upslope is basically the legal wilderness area and everything down slope is legally just forest. It looks the same on either side.
One thing of interest on this trail is the vegetation. The lower part is almost pure ponderosa pine. The upper part is some nice aspen and some spruce-fir. The middle part was at one time a decent mixed conifer stand, but it has since degenerated into a thicket of young white fir in many areas. Its interesting to see the large snags of ponderosa pine, douglas fir, and even a few white firs that have died as the young white fir juveniles have out competed them. Unfortunately, with the dry conditions in recent times the young trees don't always look so healthy and I could see this area burning up in a fire at some point, and hopefully converting to an aspen stand. This is something to think about when riding slowly up the road. Its best to pay attention to the road when descending.
This hike is listed as One-Way. When you hike several trails on a single "hike", log it with a generic name that describes the hike. Then link the trails traveled, check out the example