Dredging it.
http://www.slideshare.net/fairfaxcounty/royal-lake-dredging-and-restoration-project-pardon-our-dust-meeting-may-9-2016
It's a shame too. I've caught lots of real nice fish out of there. It was my main "secret" place around here. There were only a few people who really fished it hard. This is going to fuck it up for years.
Supposedly they're moving or have moved the fish to Braddock and Mercer. Both of those are a pain to get a kayak in though.