Pond Boss Forums POND CONSTRUCTION Building a dam Spillway size

I've acquired a new pond and witnessed some flooding this past month. There is a natural runoff area but I would rather have it run off before rising above the ponds highest point. The area my pond lies in western Washington gets approx 50 - 80 inches of rainfall a year. Most of this comes during the winter months. The pond is about two acres 20 - 25 ft deep. It is an excavated gravel pit without a dam. What do you guys suggest for a spillway. I was thinking a rip rap canal into a culvert under my driveway. What size do you recomend? What angle would be best for the canal. Would a small pond at the end of the canal help to slow the erosion? I want the water to drain but not erode too much. Thanks for your ideas.

I would still use the natural area. But, guide the water toward it by excavating a more subtle grade toward the natural area. Disturb the least amount of soil as possible. If this idea doesn't intrigue you, shoot the elevations and see where it makes the most sense to re-direct water. The answer may be obvious. Gentle slopes minimize erosion, but be sure to vegetate the slope, or use something such as riprap to slow water flow as it makes its exodus.

Thanks Bob,
The natural runoff area crosses a road on my property and can cover it with up to a foot of water. any idea on the size of the culvert to use? The culvert will be for passing under the dirt road on my property. It can rain quit a bit up in washington. 50 - 80 inches average a year. sometimes more.
thanks again for any advice

Without seeing a layout the minimum would be 36inch. Also design rock wall or conrete wall around pipe inlet to prevent errossion of incoming water removing soil from around pipe and design the inlet sump to channel water directly into pipe. If you have the room design inlet sump to retain water if there is a backup so it does not flow over the road.
Good Luck