Clean Up of Large Water Feature/Pond

Question:

I am property management for a property that has a very large water feature. Over 1/2 acre 3 waterfalls, 7 large gould sewage pumps pushing the water. We shut it down each winter and spring cleanup is a large job. I am looking for help in cleaning that debris without damaging the membrane by walking in the streams.
Last year, lots of sting algae and leave debris continued to make the ponds and streams look bad. Which products would you suggest for such a large project? The only filters on these pumps are leaf catchers going into the pump house that get cleaned daily. Help Melissa Gold in Montana