Fisrtly, if you have flow out of your pond to a creek do not add any aquatic animals or plants for any reason unless you know for a fact that they are native and you get them from another pond near by (the exception to this I guess would be water lillies, as they aren't as invasive as most aquatics). assuming it does not parrots feather could be a good solution, it provides plenty of shade. Koi might eat the algae depending on what it is. I really would suggest going to a neighboring pond that doesn't have the algae problem and seeing what natives grow there. You could also buy a pump and pump some of the nutrient rich water out and onto plants in the surrounding area, the water would be replaced by rainwater presumably and you could get some good fertilizer out of it. Also try going to clear ponds around you and collecting large water samples and handfuls of pond much from several locations about once every two months to build the diversity in your pond. Some ducks have been reported to clear up algae problems, as well as small fish and all aquatic plants.

Thank you for the reply. I will follow your sugestions. At the moment it is clear. It flooded here about 2 weeks ago.I was amazed when the water receeded the yard and the pond had hundreds of dead salmon. I had contacted the department of fish and wild life to find out what fish were in the creek and what guidelines for good stewartship they could offer. Ther Reply listed several fish including steelhead but not salmon. The dead ones were quite large and headed to lay there eggs. So now I need to really be extra careful so as not to harm there enviroment.
Yet I would love water lillies and koi. But in a flood they could wind up in the creek . Any more tips are very appricated.
Mist

Hi Mist, There are some fine native water lilies, for many areas, so, what state do you live in?
Koi are a kind of carp, and are not native, and can get invasive. But it sounds like you have been careful about checking things out. Good for you.
Hope the salmon are gone now, must have been tough for a while [phew!]. Sounds like the grand scheme of things, brought the pond some free fertilizer.
You could see if your library has anything on local bogs, or bogs in general. They can get almost any book, on interlibrary loan. There are some cool books out there. I like to check reviews on amazon. Books that are decades old, are often the best. Also, see if there is anything on your area, by a naturalist. Your reference librarian could be a great help, as she may recommend, and help find, articles, too.
Check out your county extension service, and talk to a master gardener.
Good Luck, florey