Pondside trees...what about a walnut?

Does anybody know of effects of allelopathic trees like walnuts on nearby ponds? I have a beautiful but over mature walnut just northwest of my property's low point... what seems to be the ideal place for a small pond (30x45ft approximately). The fact the walnut makes growing things in this spot more difficult seems to further indicate a pond might be the best use of the space if jugalones aren't problems for pond life. The canopy/drip line/root mass of the walnut would be the nw edge of the pond, though as I write this i realize the roots may ruin any seal. So I guess my questions are about:

How far from a pond should established trees be?

Do walnuts or other allelopathic trees have a distinct effects on nearby ponds or streams besides the general benefits of trees near water?

Thanks!

The drip line is going to be 2-3 times the distance from the edge of the branches to the trunk - much farther than people think.

Most plants are not affected by the juglone. I am not sure about aquatic animals - will check.

Are you planning to line the pond?

Thanks for the response. In terms of a seal, I was planning on allowing my ducks to gley it. I have found a heavy clay layer 1-3ft beneath the surface in the area when digging before. I have not dug deeper than 5ft or found the bottom of the clay. I would ideally like to keep a small number fish in this low point pond, with two higher smaller ponds connected to a swale-french drain system, where I keep muscovies. I only have a 1/2 acre but it feels bigger and live in an area with prolific rainfall (100" this year already) that happens almost entirely during the winter (less than 1"/month in the summer). I also could use to create some hot spots for subtropical plants, as this is an extremely temperate climate (30-90f are the low-high most years) that makes getting brix up on any fruit the main challenge.

Would you predict digging and cutting 5ft outside the dripline around 1/4 of the circumference would be greatly harmful to the tree?

That will do quite a bit of root damage, but the tree should be able to handle it. You might want to do it in fall when the tree will get enough rain to grow new roots.

Thanks, I will take your advice and put it off til the fall. Will ten muscovies do much to seal a small pond? I imagine they have less capacity to seal deeper ponds than pigs.

sorry - I know nothing about sealing a pond with animals.

Did anyone ever come up with an answer as to whether walnuts by a pond are not good for fish/animal life? I have a collection of volunteer walnuts within 20 feet upstream in the watershed, above my pond location. Hate to have to remove them.

So I just decided to answer my own question and googled "do walnuts harm aquatic life?" and this was one of the top links: http://www.funkykoi.com/list-of-plants-toxic-to-pond-fish.

Black walnut hulls are listed, but so are oaks (acorns and foliage), the prunus genus, pines, and many more common plants to north america. I know cedar and redwood tannins (walnuts are also using a tannic acid for protection) are deterrents to some aquatic life (like aggressive invasive algae and associates). This is along with having profound physical effects on a watershed (shading, water retention and condensation, humus building). So in this way even though you could accurately state that such tannic conifers are harmful to warm-water fish, they are at the same time integral to healthy salmonid (trout and salmon) populations. Therefore I would wonder, what fish live in the native habitat of our walnuts' ancestors? I bet they would be more than fine next to the tree.

Thank you :) I like your opinion better than that link's theory. That's basically a list of every plant on my property. And every plant within 100 miles of here, 90% of which grow by the creeks, rivers, ponds and lakes around here. I think they are growing some mighty fussy show Koi or something. I'm going for natives, who should be much tougher than that. I'll see how my walnut trees and fish do together. Thank you, I'll cross that one off my list. I hadn't actually considered it till I read your post. Volunteer walnuts are thick around here!