Most perennial grasses will begin to die off after being submerged in water for a few days. A few species of true terrestrial grasses can survive a fair bit longer.
Of course there are lots of other plants out there, including shore line plants that can handle fluctuating water levels and long periods of immersion.
Hopefully, most of that stuff that is bothering you will be dead within two weeks?
P.S. I like the pond and how green your property is currently. The reflection of your red shed in the pond water is also a nice touch!
