I suggest walking into the local NRCS office and see if they will design your pond for you. Mine did, even came out with transits and took measurements and flagged it. They will either give you data on primary and emergency spillway requirements, pipe size, elevations, etc or perhaps they will say don't do it due to the watershed being ~10x larger than recommended. Its at no cost to you. However not all Missouri counties have the ability, or they may be backlogged with work.

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