Ok, so this morning the green water was gone. I've attached two pics from last night, including the original on the thread, and four others from today. Completely different. You can see some of the existing grass from the original dam under water in a couple of pics.
My recent devotion to observing my pond the past 2 years has taught me do not make hasty theories. Our East Texas weather can throw some curveballs. Recent rains have turned our pond over to a muddy color, reflective of the red clay soil of my area. I'd take it slow and easy, giving things time to settle after you or mother nature has applied some kind of "change."