edible plants to plant along river

Have a central Texas homestead where a small river flows along one of the borders. There is a water treatment plant up river a ways that has caused algae to be in the water. I realize that I need to have the water tested first, but what I was looking at is to plant edible perennial plants along and in the water. Some springs flow out along the edge as well. Some of these that come to mind are cattails, arrow root.
There is some small schools of fish, so is enough oxygen to support them. Would harvested leaves, tubers be safe for me to eat? Any other ideas on edible perennials?
Some elephant ears are growing along the bank that are rather invasive, and just for looks. They may play a role in filtering out bad stuff in the water.

Some red elm trees yield a slippery cadmium of the bark, (don't kill the trunk, use the green limbs if possible) it is good to eat, & other uses, if properly dried the inner bark can be easily stored & later reconstituted with water. They generally make tall narrow trees with lots of shade, you may already have some, just need to ID them if so, they generally don't get diseased & die like some of the other elms.

I love elephant ears to look at, but it you have lots of them maybe you can trade some for plants you want.

Grape vines do pretty well next to a river and seasonal floods probably won't bother them much.

Spicebush is a shrub that grows in full shade, moist ground, crush the leaves and smear the fragrance on your skin as mosquito repellant, also some people use the leaves to make strong tea (tastes kind of like kerosene) hahaa, the berries can be kind of sparse, but when properly dried the husk of the berry is used as spice.

Paw Paw makes a deep shade under it, it often grows in thickets, is often used for erosion control because of the deep tap root, the fruit is kind of strange tasting but edible, and pretty tolerable if frozen in ice cream, the fruit is sparse & doesn't store well.

Blackberries grow along a creek/sandy areas well, get the thornless (non-native) kind if possible, but they need a spot that won't get the thicket trampled often.(maybe fence off a plot)

I can't see eating a cattail, but hey if you like 'em, sounds like you got it made.

Sassafras leaves eat pretty good right off the tree, and if you dry the leaves properly they store well & you can make spice out of them.

james beam

Thanks.
Have lots of mustang grapes. Didn't mention that. Course, deer get most of those.
Been meaning to try pawpaw, blackberry. Cattail has lots of uses. Want to try it as a flour and make bread.