Pond Boss Forums INTRO Questions & Observations spillway elevation

what a great site........info superhighway.......
ok i got a 1 & 1/2 new pond just being built.....i got a small dozer so it has taken lots of aftrernoons......60 % will be less than 3 feet deep..........deep holes will be 9 tp 11 feet.........it has a 6 foot wide top on the dam at the smallest spot.....most is wide enough to drive dozer over.......it's about 10 to 15 feet wide at base of dam......i need to know how wide & deep from the top elevation of water to make spillway.......?.......would anyone use a pipe ?.......if so how big ?.........i'll be waiting on a reply as i'm allmost ready to dress up the bottom......& built flood controll system.....thanks ........

You don't mention where you're located...but in Texas, many ponds have a simple spillway, no pipe. The advantage of pipe is that you can divert runoff away from the back of your dam, eliminating erosion. I can't help you with pipe, but if you go for a simple spillway, generally it's 36 inches lower than the top of the dam. As for how wide ? That's determined by the size of your watershed area and 24 hour rainfall thresholds. My pond has approx. 75 acres of watershed, and my spillway is 15-20 feet wide. Also, you may run into trouble with birds & weeds if 60% of your pond is < 3 feet deep.

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

Eastland has good info. I had started a reply and got sidetracked while looking up that NRCS site. Didn't mean to duplicate his info., but great minds think alike, right?

thanks for all the great info..........here are a few more details........it's gona be a pond for cows........but i also semi pro bass fish wanna be,,,,,,,so i have gave alot to making under points......sharp turns & fast ledges plus i will be putting in a windmill & bottom air.......i live in east texas.....we have great clay here ....can i use a pipe to controll most of rainfall......& a spillway for the flood waters......this tank is fed by a ditch & when it rain good it's moving some water.......if i put a pipe thru dam [ 6 inch] & put a 8 inch pipe on a tee with the tee being at water level .how far below & how far above with the 8 inch pipe do i go...thanks guys

Stroker,
Check out ponddampiping. com for a syphon spillway system.
Has worked well for our East Texas pond - only a emergency spillway needed.