LeeinMemphis:

This sounds suspiciously like a pond I worked a few years ago in the western reaches of the Texas Hill Country. Full, it would have been a 1.5-acre slice of heaven surrounded by miles and miles of deer, turkey and other critters on large, remote ranches. As it was, however, water that was 15 feet deep after a rain would quickly drop to a depth of 4 feet.

Enter Mr. Wizard here, with a few tons of sodium bentonite and a well-trained crew. Two days and a total of $11,000 later, we had an awesome pond that would hold 7 feet, no more.

Rain would fill it to 15 feet. Instead of retreating to 4 feet, it stopped at 7 and held like a jug.

Lee, check your site for fissures or formations of gravel. Here in the Texas Hill Country, they're pond-killers.

BTW, the landowner was good-natured about it, and chalked up our limited success to a fissure in the sidewalls of the pond basin, which allowed the water to escape.

It should be noted that I have never been invited back.

Mark McDonald
Editor