Stroker:

Welcome to this site. There is lots of info. here and lots of helpful people. It sounds like you may be about where I was a year ago. I'm no expert, but there are many experts here. Just thoughts I have...

One recommendation I've read in lots of books and on this site is to minimize the amount of your pond that has water less than three feet deep. Too likely to result in weed problems which could lead to too many small fish. 60% sounds like a whole lot.

Which leads to probably the biggest question the pros here have... What is your primary goal for the pond? That impacts everything else...

As to your specific questions... The actual width and depth a spillway should be depends upon a lot of factors. You need to provide an estimate of how much water to expect. For instance, I have a 10-12 acre lake. My spillway is five feet deep and probably twelve feet wide. We have had a LOT of rain lately and at one point the water was flowing over the spillway about a foot deep and eight feet wide. My watershed area is about 120 acres which is almost entirely farmland. As I said, we've had a LOT of rain lately and the watershed is saturated. That rain pretty much all ran off into my lake. It would have taken a really big pipe or a lot of freeboard to handle that much. A few years down the road, I plan to make my spillway shallower and wider so I can drive across it.

I considered a pipe. There are lots of advantages to a pipe, but my neighbor had his pipe rust out and water was eroding his dam as a result. Therefore, I went with a spillway and think many recommend them as opposed to a pipe for that reason. If you go with a pipe, usually bigger is better. Watershed and rainfall information would help determine the correct size.

The NRCS guide that helps you estimate your spillway size is at the first link below (page 46). It also has a lot of other helpful information.

http://209.234.81.2/images/pdf/PondsPlanDesignConstruct.pdf

http://www.nrcs.usda.gov/technical/water.html

http://209.234.81.2/product.asp?ID=115

Good luck and hope this helps!

Jeff

[Linked Image from i108.photobucket.com]