This was observed by the Pinnacles Vegetation Crew and a volunteer group while pulling weeds at Bear Gulch Reservoir. They passed the photo on to me.
Common Whitetail Skimmer Dragonfly, Redding, CA, USA.
A very cooperative subject in the setting sun - it allowed me to creep up to within 12" for this photo.
The skimmers or perchers and their relatives form the Libellulidae, the largest dragonfly family in the world. It is sometimes considered to contain the Corduliidae as the subfamily Corduliinae and the Macromiidae as the subfamily Macromiinae. Even if these are excluded (as Silsby does), there still remains a family of over 1000 species. With nearly worldwide distribution, these are almost certainly the most often seen of all dragonflies.