Best resource I've come across is from NRCS. It's an excellent, free
publication
on pond construction entitled "Ponds - Planning, Design, and Construction"
(Agriculture Handbook 590). Contact your local NRCS office for a copy. I
haven't
located it on the web, just on paper. Natural Resource Conservation Services
(NRCS)
is a US government agency and part of the US Department of Agriculture (USDA.)
The publication covers engineering, site placement, spillways, and more.
Paul
Taos, New Mexico (Cold, Dry, Montane climate)