I'm in zone 5a and I would go about 3 feet just to be safe but I don't think it would even get 2 feet freeze here. You could probably do 2 feet and be fine. One thing to keep in mind though is if you are going to keep goldfish you aren't just worried about depth for winter but to keep the water cooler during the summer, fish like deep and cool water then and 3 feet would probably work for that. If you want to keep koi I would do at least 4 feet to keep the temperture from fluctuating and just because those big guys need the room. Good luck!

gotcha.. i was thinking 5' is good.. maybe 4 1/2'

also what are my options besides goldfish, koi and turtles i can have in my pond.. any really cool looking plants?

If you want to do plants you might do several depths a shallower part for plants or plant shelves around the edge about 12 inches down.

There are lots of plants. I like water lilies, papyrus, parrots feather, watter lettuce, blue pickrell, iris, cattails just to name a few. You can also grow annuals on little floating islands and things like that and lots of planting options around the pond too depending on if you have a sun or shade pond.

are there any evergreen plants? or perennials that will come back the following year? remember it can get into the teens here in the winter.

Yes, look for things that say hardy and stay away from tropicals like parrots feather or bring tropicals indoors. Hardy water lillies will come back and bog plants I sink into deeper water so they don't freeze and bring them up in the spring. Although I've had plants like cattails freeze solid and still come back some are pretty tough!!!

I think 4 feet minimum for koi. We were glad ours was that deep after this really cold winter. We didn't lose any fish.

I think 5 feet is the ideal depth. If you are going to have turtles make sure they are not red eared slider; they are very invasive. The Eastern painted turtle would be the best species for your pond. Also, make sure a basking platform is available for them, it could either be a big rock or a log.

I had heard that raccoons don't swim so I made mine 3'+ deep. They came into the bog areas and tore things up but the plants in the middle were left alone - until this year - they must have taken swim lessons I know they have been to REI and have taken climbing lessons to get over the fence. They really like the iris corms so I've taken all of the iris out. I'm concerned about the marsh marigolds now. Horse tails have been a play thing and haven't held up - neither has my disposition.

Contraryjim

When does building departments normally require plan approval and construction permit to be issued? I seem to remember if the pond is more then 18" deep you would need a permit and that for safety, it could be regulated as a pool.

Sadly, it is a local thing. The rules differ from one community to another. Here it seems to depend on the subdivision rules. I spent an entire year trying to find out what the rules might be with no luck. Then a neighbor told me about a woman from the city who dealt with all the subdivisions and she told me that so long as it was 10 feet from the property line there should be no problem. I find that disturbing but I have my pond.

Hi Austin,

I added a deep addition to my pond for the sole purpose of helping my koi over winter successfully.

I went a little overboard and dug it 6 feet deep. I wanted to be sure I got below the frostline as it gets very cold in northern WI in the winter. And, my boyfriend - who is an avid angler and familiar with ice formation on bodies of water - had convinced me that such a small body of water would freeze solid. He was wrong by the way.

In the end, I checked the ice level just as the spring thaw was beginning. It was no more than 8" deep and even the main pond which is 34" at its deepest didn't freeze to the bottom.

I did keep aerators going under the ice all winter which may have impacted how much ice formed. Good, news though, is all 6 koi made it through happy and healthy.

I would agree with most people here and say between 4 and 5 feet would be MORE than adequate.

Jenny

I'm in central il, and my pond is ~30" at it's deepest point. This past winter was brutal cold (for my area) and the pond froze down about 12". It might help that for the most part 2 sides of my pond are within 18" of my foundation. I suspect some warmth from the basement is keeping the soil above freezing.

I also keep a bubbler on all winter, but that doesn't stop it from freezing over. I've only lost 1 fish to the cold in 3 years. And it was struggling before winter started.

And I can't imagine the effort required to dig down 4 or 5 feet. I had enough trouble digging down 30" by hand.