Pond Boss Forums POND CONSTRUCTION Selecting a site Calculating Watershed

Can someone explain how to calculate watershed exactly? I'm not sure how much of this I will actually collect at the bottom of the hill. I will calculate the property to the north also, but hope I don't have to depend on it for a 2-3 acre lake. I believe I also get a good bit of watershed from the road at the top of the hill. I estimate I have about 15 acres of watershed to fill up a lake close to where i have the dam line drawn on the map. I have a small pond where the small cirlce is. I also have a spring coming out of the side of the hill, but I believe it is just wet weather flow from the porous soils atop the hill. I have an average 51" rainfall annually.

The square is 17.3 acres. The long sides are about 1200' and the left side is about 450'. Let me know if I need more info. I'm just looking for help with the watershed acreage so I can continue my calculations. Thanks

Assuming your dam is the red line, the blue line delimits the extent of the watershed. The road drainage could increase or decrease the area depending on where it is channeled.


Go to this page find your property and outline the watershed. The planimeter will calculate the acreage.

Thanks Jsec, that's a great site that figures the acreage.