In Pennsylvania, a pond needs a Dam Permit from DEP when its dam has more than 100 acres draining to it, holds water more than 15 feet deep at the dam, or stores more than 50 acre-feet. Many small farm ponds sit under all three marks, but a pond on a stream or in a wetland can still need DEP and Army Corps approval, and the digging itself falls under the state erosion and sediment control rules, so call your county conservation district before any dirt moves.
The three numbers behind a Pennsylvania dam permit
The Pennsylvania Department of Environmental Protection runs pond rules through its Chapter 105 regulations. Its Division of Dam Safety requires a Dam Permit for a new dam across a watercourse when any one of three things is true. The contributory drainage area is more than 100 acres. The water is more than 15 feet deep, measured at the upstream toe to the top of the dam. Or the pond can hold more than 50 acre-feet. DEP gives its own example of that last one: a 50-acre pond that averages one foot deep holds 50 acre-feet.
A dam that meets none of the three is what DEP calls non-jurisdictional, and the Dam Permit does not apply to it. Many backyard and farm ponds land there. It is not the end of the list, though, because the stream, wetland and erosion rules below apply on their own.
Off-stream or on-stream makes the biggest difference
DEP draws a hard line between a pond dug off to the side and a pond built on a stream. Its guidance says Chapter 105 approval for water obstructions and encroachments is not required for a pond proposed off-stream, as long as it is not in a floodway, a wetland or another body of water. Put the pond on a creek, or dig it into a wetland, and things change. DEP says it strongly discourages both. A small dam across a stream, or one that affects a wetland, may need a Water Obstruction and Encroachment Permit or approval of an Environmental Assessment, and lost wetland or stream has to be replaced.
There is a less obvious problem with ponds on streams: heat. DEP notes that water leaving a pond in summer can run 8 to 10 degrees warmer than the stream coming in, which can lead to a thermal impact review. Federal rules sit on top of the state ones. DEP says a Section 404 authorization from the U.S. Army Corps of Engineers is likely required for fill in wetlands and watercourses.
Erosion control applies to every pond
Digging a pond is earth disturbance, and Pennsylvania regulates that under Chapter 102. DEP says an erosion and sediment control plan is required under Chapter 102 even when no Chapter 105 permit is needed. The state code calls for a written plan once total earth disturbance reaches 5,000 square feet, which a pond, its banks and the spoil area pass quickly. At one acre of disturbance, most projects also need an NPDES permit for construction stormwater. Your county conservation district reviews erosion and sediment control plans, so that is the office to ask what your pond needs on paper.
Who to call in western Pennsylvania
DEP calls delegated county conservation districts a good first stop for pond questions. In Mercer County, the conservation district lists help with erosion and sediment control and with stream and wetland impacts among its services. Every county around Pittsburgh has its own district, so look up yours. Add your township or borough zoning office, since local rules on ponds vary. DEP also points landowners to the Natural Resources Conservation Service and Penn State Extension for planning advice, while noting they cannot interpret the regulations for you.
Then there are buried lines. Pennsylvania's Public Utility Commission says homeowners and contractors must contact PA One Call at least three business days before digging. Our guide to calling 811 in Ohio, Pennsylvania and West Virginia covers who places the notice.
Reworking an old pond
Plenty of Pennsylvania ponds already exist and have filled in with silt. DEP says that once built, every pond is regulated water of the Commonwealth under the Dam Safety and Encroachments Act. Its regulations include a waiver for cleaning out a small, non-jurisdictional pond back to its original capacity, and DEP says it does not regulate repair and maintenance of non-jurisdictional dams. For sediment removal, DEP notes that the Pennsylvania Fish and Boat Commission may require a drawdown permit. Ask before you drain the pond.
Will the spot hold water
Paperwork aside, a pond lives or dies on the ground under it. Much of western Pennsylvania is hill country, and the easy spot for a pond is often a draw where water already runs. That spot makes a dam pond, and a draw that carries a stream brings the on-stream rules. A dug pond on flatter ground, fed by runoff or a spring, avoids most of that. Either way the bottom has to seal, so test holes come before the real dig. A pond also needs an overflow that carries high water around the bank instead of over it.
What we do
We dig new ponds, shape and grade pond banks and clean out tired old ones, using a tracked excavator, a dozer and a compact track loader. Mercer County is close to home for us, and we travel farther into western Pennsylvania for bigger jobs. Before the estimate, it helps to know what your conservation district and zoning office said. See our pond digging and pond bank shaping page, or the Ohio version of this guide: do you need a permit to dig a pond in Ohio.
Common Questions
Does a small farm pond in Pennsylvania need a DEP dam permit?
Only if the dam crosses one of DEP's lines: more than 100 acres draining to it, water more than 15 feet deep at the dam, or more than 50 acre-feet stored. Under all three, the Dam Permit does not apply. A pond on a stream or in a wetland can still need other DEP and federal approval, and Chapter 102 erosion rules apply to the digging.
Who do I call first about building a pond in Mercer County, PA?
Start with the Mercer County Conservation District, which helps residents with erosion and sediment control and with stream and wetland impacts, and with your township zoning office. Between them you will learn what applies on your property. Then call Jeff at (330) 625-5754 to walk the ground.
Can I build a pond on a creek in Pennsylvania?
DEP says it strongly discourages ponds built on streams. A dam across a stream may need a Water Obstruction and Encroachment Permit or an Environmental Assessment, plus federal approval, and the warmer water a pond releases can bring a thermal review. A pond dug off to the side of the creek, out of the floodway and any wetland, is usually far simpler.
What to Do Next
Make the calls first, then call us. Jeff will walk your site, look at the ground and give you a free estimate once you know what your county and township want. Reach him at (330) 625-5754. See the pages for Mercer County and Lawrence County, or our excavation services.