Nevada Test Site Tours - Department of Energy, Las Vegas, Nevada
Nevada Test Site Tours - Atomictourist.com

One of the Nuclear Bomb test sites in Nevada, the map above shows the locations of the various areas designated by number. (Area 51 would be to the right of this map) Shundahai Network has an excellent website with details about these areas... for our purpose we are only interested in Area 19... and why it was not used.

Area 19

Key Excerpts:

...This area, within the Nuclear Test Zone, occupies 388 km2 (150 mi2) in the northwest corner of the NTS.

...Area 19 in the northwest coner of the test site was originally developed as a suitable location for higher yield underground nuclear test (over several hundred kilotons). No atmospheric nuclear tests were conducted in Area 19...

...From the mid-1960s through 1992, a total of 36 underground nuclear tests were conducted....

...The geology of Pahute Mesa makes it possible to test devices at much greater depths than in Yucca Flat (down to more than 13,700 meters (4500 feet))...

...It was the recollection of a former worker at the NTS that "an awful lot of drilling" was done in Area 19, but relatively few nuclear blasts. He says there was a story released that the drillers hit an underground lake, as a result the NTS was not able to fully utilize the area. 

SIDE NOTE:

NASA's Apollo astronauts use Test Site craters to prepare for Moon surface.

Because the "Schooner" and "Sedan" craters at the Nevada Test Site had features similar to the topography of Moon craters, astronauts used them to train for their missions.

Astronauts for Apollo 14 exercised at Schooner crater, and visited Sedan crater in November 1970. Apollo 16 astronauts visited the Schooner crater in November 1970, and exercised there in October 971.

Apollo 17 astronauts conducted exercises at Schooner and on Buckboard Mesa in August 1972.

SOURCE: Shundahai Network Area 19

"Another rumor comes from a former worker at the NTS. It was his recollection that "an awful lot of drilling" was done in Area 19, but relatively few nuclear blasts. He says there was a story released that the drillers hit an underground lake, and as a result the NTS was not able to fully utilize the area. This seems to tie in with the fact that while there were a goodly amount of blasts done in Area 20, and some in the southerly part of Area 19, the records show very few in the heart of Area 19. The worker did seem to think there was something '"odd" about Area 19."  - by Tom Mahood