I had an 11 acre pond built in Northwest Louisiana (Shongaloo, La, to be exact), and it was completed in early December. With all the rain we had, it literally filled up by mid-December. It's still murky-ish from, I believe, two causes: it's a new pond with little shoreline vegetation, and also there appears to be a colloidal clay problem.

Question is: if I want to later buy gypsum to handle the colloidal clay problem, WHERE do I get it from? I can't seem to find any place remotely close to Shongaloo, La that sells bulk gypsum.

Any advice is most-appreciated.