Thunder Mountain Lakes are found in the Alpine Lakes Wilderness. The area is increasing in popularity, and the lakes are set in a highly sensitive area, so it is important to practice Leave No Trace principles should you decide to visit.
That means to only camp on durable surfaces (not on grass), pack out everything you pack in with you (including your poop) and if no campsites are available, head elsewhere for the day, even if it means heading back to the trailhead.