Not too far off the trail, just before the turn off the reservoir road, there is a thin green post with a thin black tube standing up in a bit of a clearing. If you are fortunate, you may see it spurt and gurgle! Sometimes there may only be strange noises coming from the tube or nothing at all. (Let us know what you see and hear.) Note: The post and tube may be gone, but there is a large metal pipe sticking up now.
If you step just off the trail you may also spot a cache. The original Gerrygonz1-style container seems to have gone missing -- the container is now something that looks like something else. The cache is not winter-friendly.
The cache is almost half a mile from the trailhead parking. Continue on for many more caches on the way up the mountain. There is a new trailhead map kiosk to show you the way.
Thanks to Capt. Bob for the name and to Lost From New York (the cacher formerly known as Gerrygonz1) for the original container giving a reason to place the cache.