The Wathen Trail is really nice, but it is getting to be in pretty tough shape. I am afraid that cyclists have caused much of this. Wathen is very steep and techy in sections, and those sections seem to be erroding quickly, probably due to the improper use of bike brakes.
On steep, techy descents, locking one's brakes might seem like a good way to slide through safely. In reality, while sliding a rider can't steer effectively. Just as it's important to avoid locking a car's brakes on snow to stay in control, it's important to use bike brakes correctly for safety. Try to apply only as much brake pressure as needed to slow down with the wheels still turning. This style of breaking is safer, faster for racers, and also much better for the condition of trails like Wathen.
Wathen is a blast to descend. I often start rides at Horsetooth Mountain by climbing the initial service road to its end, taking the West Ridge Trail to the top of Wathen, then descending Wathen onto the Spring Creek Trail. Always good for a grin.