Urban ponds

I am considering a pond for rainwater catchment/storage, habitat and aquaculture. I need help sizing it for my land and situation. I live on .19 acres of which 1000 sq ft is covered by my home. It will be located in the back yard and be fed by roof runoff. In the wettest month I should be able to collect around 2,000 gal from the roof. I am in USDA zone 7 and have aprox 33" annual precipitation.

Here is a calculator for determining a pond's capacity: http://www.lagunaponds.com/lagunaeng/calculators/watercapacity_round.cfm

Thanks for the link! I guess I need to be more clear about what I want to know. How much land should I be willing to give up for a pond? How much water should the pond hold to accommodate the rainfall I get?

Chad Ellis wrote:Thanks for the link! I guess I need to be more clear about what I want to know. How much land should I be willing to give up for a pond? How much water should the pond hold to accommodate the rainfall I get?

I think only you can answer the question of how much land you want to dedicate to a pond / wetland area. In my situation I am dedicating 25% of my land to a pond / chinampa system, 25% to a high intensity veggy garden, and 50% to a food forest. Those numbers could easily change based on what your goals are and how you want to accomplish them. I decided to go with 25% because I have been successful at raising tilapia and red claw crayfish so far and would like to expand it. Also that area is already slightly lower than the surrounding land so that influenced my decision. As with everything results may vary, decide what your goals are, how you can accomplish them, and work with what you got to achieve them.

I don't know if there is a volume to rainfall guide or percentage, I would be very interested if there was. You could take your average rainfall, ~2.75' x Surface area of your catchment (pond area + roof area + any run off area)= Total cubic feet of catchment / year. Type "convert xxxx cubic feet to gallon" into Google search bar and it will convert it to gallons for you. This will give you a rough idea of how much water you can catch in your pond system. From there I don't know what to do hahaha but at least then you have an idea of the total volume you are dealing with, granted this volume won't all be at once but over the course of a year. Hopefully someone else can chime in and lend some expertise. I think it would also be very important to have an overflow leading to a drain field area, as well as, a way of diverting water from the roof to somewhere else in the event the pond is full, or just to CYA in case of a monsoon.

if you are in an urban area you do have your neighbors to consider..I would make any catchment pond at below ground level if there are not problems with septic lines, elec wires, etc. You should always have those marked by your dig site before digging. Do you have any slope with any standing water areas on your property? If so that is the best place for your pond. You should design it to be best used by your property thinking of what you intend to use it for. wildlife mostly.. fire prevention..growing water plants and maybe some goldfish or koi..whatever. Site it where it will best work for those things. Some shade on the pond can be helpful as you won't have an inlet other than rain..but overhanging trees can pollute the water so think of that, also where digging might damage existing tree roots.
do you want to hand dig or use equipment? do you have clay so it can be a natural bottom or do you require a liner. where will the overflow go?

Sepp Holtzer's new book has some helpful info but you can also go the the library and borrow books on pondbuilding.

I am in an urban area. The existing privacy fence should get rid of most considerations about neighbors. I planned to keep it at ground level. I have primarily sandy soil and will be using a liner. It will be hand dug. The backyard is on the west side of the house and there are large oak trees on the west side of the yard so it should receive mid-morning to early afternoon sun. Currently the water off of the roof just goes into the yard so run off should not be a problem. I could set it up where it goes into one of the garden beds though. I primarily want to attract some more wild life and use the ware to irrigate the garden beds. Some native fish would be used for mosquito larva control.

I like your idea of using your water storage device to grow stuff.

12'x16'x 3'deep will give you over 4300 gallons. keeping a "low-tide" of at least 1' deep for the fish should allow you almost 3000 gallons of buffer capacity, but i think pond sizing is more of a motivation to dig problem.

ps. each good shovel full of dirt is about a gallon.

Paul talks to Jocelyn in this podcast about professional trolls, backyard ponds, local vs organic, composting, and lots of other listener-question subjects: podcast 112

Thanks!

I have a small preformed pond + homemade biofilter that I have had in my yard for about 12 years: https://permies.com/t/4468/homestead/pond-biofilter



I put it there because:
1. I wanted to attract wildlife. I especially wanted to see if I could attract bats (which I don't think it did, but it attracts just about everything else, especially birds).
2. I wanted a small pond to experiment with.
3. I wanted to play with a complete little ecosystem. If I were king, every kid would have a pond in their backyard and several at school. There is just an amazing amount to observe in a natural pond.
4. It was dirt cheap because it had a small hole in it (which I repaired with a glue gun).

Overall the pond was a great success, and I am about to put in a few more.

The greatest thing about ponds IMHO is water plants, because the water plants basically require no care (I mostly have plants in pots in the top of the biofilter). They look great all spring, summer & fall, even when the rest of the yard is basically dead due to our summer droughts. I never fertilize them, the creatures in the pond take care of that for me. I do have to add a bit of additional water July-mid Sept, and I put in a recirculating pump April-Sept. to keep from breeding mosquitoes (I don't want fish). I have cleaned the pond twice and the biofilter once in 12 years, but now I don't think that was necessary. So the only inputs are 1) a bit of water (maybe 40 gallons) and 2) about $15 worth of electricity. I have never moved anything alive into the pond except for the plants, and one stupid experiment with duckweed (which I later carefully removed). All the life in the pond showed up on its own. And there is a LOT of life in the pond.

I don't want fish in the pond because:
1. I don't want to attract fish predators (mostly raccoons)
2. I don't want to have to feed fish
3. I don't want the pond ecosystem to have to deal with fish waste

As far as size, I think it can be whatever you want, it depends on your goals. One of my main goals is "lots of life with little or no maintenance" so I am converting a fair amount of my yard to ponds/wetlands.

The only downsides that I have experienced are:
1. My pump finally died and I took too long to replace it and ended up hatching mosquitoes one year. But I think my little pond has very little influence on whether the mosquitoes are "bad" in my yard. The weather is really the only factor determining how much blood I involuntarily donate.
2. Occasionally raccoons will overturn things in the pond, especially potted plants. I have learned to put a lot of gravel in the pots which makes them a lot heavier.
3. I wanted to see what it would be like to have some duckweed in the pond so I brought a handful home and put it in the pond. In a matter of days it completely covered the surface and any creature that touched the surface. I decided I didn't like that because I could not see anything in the pond, so I used a strainer to strain it all out over a period of several weeks. If you get every little bit, it does not come back. Although I suppose a duck could bring it back but I have never seen a duck try to use my little pond.
4. The pond does of course attract frogs. Frogs can be VERY loud during mating season. Some people around here don't like ponds for that reason. Fortunately we have a large yard so the pond is not near any houses. Here are some recordings I made of of frogs in the pond: http://www.freesound.org/search/?q=pacific+chorus+frogs&f=&s=num_downloads+desc&advanced=0 (use headphones if you have them - most are recorded binaurally). You should decide if you can handle that sound most nights all spring.