I'm sure it's been talked about here already so excuse me for that if it has. How swallow can it be before you have to worry about vegetation becoming a problem. I k how catails grow along the side of the pond and real swallow water. I dont want to have to dig it all very deep if its not going to be a problem with weed growth.

For submerged plants, water clarity also matters. Ponds tend to accumulate sediment, so dig deeper than you want the pond to be. Depth is also important for winter protection of fish.

It's about 9 feet deep already and raises the damn about 3 more feet. My concern is the swallows and weed control.

Swallows?

added after rereading: do you mean shallows?

If your goal is to have as little vegetation as possible then make the banks drop off as steep as possible, add rip-rap rock along as much of the shore line down as far a you can afford (3-4" water depth), and over stock with crawdads.

This was not my original goal entirely, but that's what has happened at my pond. The steep banks reduce the shallows, the rock reduces available real estate on the mud floor, and the craws eat the plants and keep the water muddy enough to reduce light penetration. However, I have been culling craws to improve clarity to actually promote some plant growth.

Most of the submerged plants for the Midwest that I have read about can reside in 6 foot of water so long as the water is clear enough, water quality is good, and the nutrients are available. It all depends on your pond conditions and what plants hitch hike in.

One thing to consider is that steep banks can be a drowning hazard. The flip side is, extended shallows will fill with plant life and reduce your open water acreage.

Yes I meant shallows. My bad. I would like at some point to get some type of visibility. I just don't want cattails and weeds to be a problem. Thanks for the response fellas .

I maintain a natural pond edge but do not allow cattails. I pull these as they sprout until the plants that I specifically chose and planted occupy the edges and largely exclude the cattails. Only my oldest pond has no volunteers at all anymore. Seedling cattails are easy to pull, but once they get established, they can be difficult to get under control.