The destination is a seasonal water pond 0.7 miles north of where the First Water trail starts its steep descent to Second Water Spring. It's an 8 mile round trip from the First Water trailhead. We started at 7 am on a 100 degree day and were out by 10:30 with the temperature in the low 90's. We hoped to find some animals around the tank but there weren't even any tracks.
While we didn't see any large critters, there were a number of small ones: Diamondback Rattler, Tailless Whip Scorpion, lots of Leopard Frogs, caterpillars, grasshoppers, and dragonflies. I'd guess that the larger critters moved to higher, cooler country even though there's been water during the monsoon.
I haven't been able to find anything on the history of the tank but it is similar to the one in Garden Valley and was probably associated with the First Water Ranch.
The trail starts north exactly from the point opposite where the First Water Trail makes a sharp turn south and steeply down to Second Water Spring. The trail starts by crossing a small ravine then the rest is flat. The path is fairly well defined and is shown on most topo maps as a secondary trail. The start of the trail was 140 feet farther east than shown on my Garmin Topo map.
There are great views of both Four Peaks and Weaver's Needle from near the tank. I climbed the side of Hackberry Mesa trying to to get a photo containing both the pond and Four Peaks. There were two many trees and bushes to see the pond once I got high enough to have a clear view of Four Peaks.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.