Pond Boss Forums POND CONSTRUCTION Building a dam Primary Spillway Design

I am in the process of planning a 1 3/4 acre pond. I am looking for designs, diagrams and other info to consider when planning a primary spillway 4-6 feet below the surface.

Thank you.

Randy,

Welcome to Pond Boss. In response to our question about spillway construction, a number of folks here have received good advice from their local NRCS. Both my ponds are excavated so I've never dealt with dams or spillways but the NRCS might get you started in the right direction.

Russ

Thanks Russ,

I am working with NRCS on this pond. The original plans call for a pipe spillway at surface level plus an auxillary. After the plans were drawn, I learned more about the benefits of a below surface drain, and I have asked them for recommendations.

However, I want to see what others have done.
Otto's article in a PondBoss issue last fall refered to some diagrams, but I could not find them in my copy of the magazine.

Other issues include at what level do you make this drain. I believe I have read that if the pond is more than 6 ft deed the drain should be at least 6ft deep. Assuming the is deeper than six, how close to the bottom should it be?

If you have a damn...a Pipe spillway is your best way to go. Put a 90 degree elbow on it so that the opening is facing up. That way you will always maintain the same water level in your pond. If you want a more natural look, go with a creek spillway. Use a rubber linner and plenty of rock.

Hi Randy;

There are lots of threads on spillways and drains here. Try searching the Pond Construction topics for these words: spillway, drain, siphon, and pipe.

I believe there are advantages and disadvantages to all the different means of letting water out of a pond. Investigate what those pros and cons are and try to decide which method would be best for your pond, watershed, and likely pond management approach. Some of the questions to answer to help decide are:
-How much water is likely to flow thru your pond, due to local rainfall, evaporation, the size of the watershed, and any permanent springs or streams running into the pond?
-What portion of the year will water be running out? Just for a month or two, or all year round?
-Is Winter freezing a concern?
-Will you want to be able to drain water at will for Winter drawdown pond management?
-How much money do you want to spend on the drain/overflow/pipe/valves?
-Are you going to push the envelope on the biomass of fish in the pond? If so, a drain system which will draw off bottom water may be called for.