Dear Ron:
Welcome to PB. As a new pond owner myself, I can assure you that you are in the right place for advice.
I knew nothing about pond management; but, luckily, I found this site and quickly learned that everyone on here will go above and beyond to help you with your pond. Don't hesitate to come to this forum with questions. Someone on here will have the right answers for you.
I also would strongly recommend you subscribe to Pond Boss Magazine. Each issue is chocked full of valuable information for managing your pond.
I bought our place last August in King George, about 30 miles east of you. Like you, I have an older pond (built in '63) that was seriously neglected. It's about 4.3 acres and when we bought it, it had over 70% coverage in watershield.
Largely as a result of what I learned and who I met through PB, since last August, we have limed the pond, put in fish feeders, added an aeration system and totally eradicated the watershield.
Here's a before treatment pic from March just as it was beginning to emerge...
And here's a photo from last week, 14 weeks post treatment..
Grass carp are basically useless against watershield. However, they may help you with other vegetation that you cannot see because of the watershield infestation.
I do not recommend raking the watershield off. If it is like mine, the stalks are going to be so thick that it will be a never, never ending battle. Be forwarned that chemical treatment for your 12 acres will not be cheap but, by far, it will be the most effective and economical in the long run.
I would certainly reach out to CJBS2003 on this site and see if he can come for a visit. He is our Biologist Extraordinare and lives pretty close to you. He does not do this for a living or any pecuniary gain so I think his advice will be as invaluable to you as it was and has been for me.
If you would like to know more about products, vendors, etc I used for our pond, shoot me a PM and I will be happy to give you all the info I have.
Once again, welcome to PB and best of luck with your newest endeavor.
With best wishes and warmest regards,
Paul