I've been waiting eight months to post this thread.
Last March, 2009, this mud pond was dug in good clay soil. We didn't have a spring as a water source in or near the new pond. Instead we planned to draw water off a spring-fed brook that came from a field above me.
We put in a bottom drain, not as expensive or sophisticated as the agra drain we used for the "lake" used for the "ki-shusui project" , see link.
the drain ran to a gate valve and from there to a ditch and field.
We calculated that this pond had a capacity of 250,000 -300,000 gallons.
The shape was dug freehand behind a small antique barn which is now the pump house. the length is approx. 130 feet long by 40 feet wide by 10-12 feet deep.
these first pictures are of the construction, with some close-ups of the drain.
And not long after this, THE CHALLENGE began.