I did not see any rule or sign that restricted campfires at Chittenden Lake. All Ansel Adams wilderness rules apply.
This trail is listed as unmaintained, but someone who knew what they were doing (probably a ranger), put a lot of effort this year in resetting the ducks (stacks of 2-5 rocks) that mark the trail. Nevertheless, it is still a little difficult to follow and someone in the group should have route-finding skills.
The Chittenden Lake Trail branches off of the Lillian Lake Loop
Trail south of Stanford Lakes, just before the point where the Lillian Trail starts its serious climbing over the ridge towards Vandenberg Lake. About 50 yards from the junction, the Chittenden Trail crosses Shirley Creek and then gradually climbs for about 0.5 miles until it reaches the beautiful falls and cascades coming from Shirley Lake. Along the way, if Chittenden Lake is still overflowing, you can see the high, thin falls coming down the rocks from it.
From the bottom of the cascades, the trail climbs for 200-300 yards until it comes to a relatively flat marshy area. At that point, you need to turn left, cross the creek, and make the steep, final climb up to Chittenden Lake. If you fail to make this turn and continue climbing up the right side of the marshy area, you'll end up at Shirley Lake, which is not nearly as beautiful as Chittenden.
In mid-July 2019, there were snow patches that obstructed the trails to all of the lake basins. I did not have too much trouble working around these patches, or walking on top of 10-15 foot patches where necessary. Snow was no more of a problem on this trail than it was on any of the others.