A neighbor of mine has three ponds in a chain on a small mountain creek. The first pond is about 1.4 acres, and has about 350 acres or so of watershed. The second pond is 4 acres and has nearly 400 acres total watershed. The last pond is about 7 acres and has a total of about 425 acres of watershed. We get about 47 inches of rainfall a year. He doesn't have problems with silt in the first pond because the creek carries relatively little silt even in floods. The other ponds have some silt problems due to the disturbance of the land in the upper parts and between them when building them. He has big overflow pipes, and enormous emergency spillways. In a big flood of 2011, he said the emergency spillway on the big (last) pond was running about 4 feet deep and 90 feet wide at peak flow. He usually drops the level of the middle pond about three feet in late winter in anticipation of spring flooding. Large, heavily fortified emergency spillways are the keys in a larger than needed watershed.
His watershed could support a 40 acre lake if he could build taller dams, but it's not practical in that steep valley as they already are near maximum height allowed without a lot of engineering, permitting, and concrete pouring.
I think you need to either look elsewhere, or build a 10-12 acre lake.
Last edited by John F; 08/08/17 10:10 PM.
