Does anyone here know for sure how the "Annual Rental Fee" for docks calculated by the DOE?

I've read the DOE docs which say "An annual rental fee equivalent to 5% of the market value for an equivalent area of beachfront property shall be paid to the Department prior to starting operations of these overwater structures."... but the only way I can interpret this is 5% * my property's value * (fraction of my property lineal waterfront occupied by the dock).

My limited understanding leads me to believe if my property were worth $100,000USD, with 100 feet of frontage, and my dock was 6 feet wide where it meets the beach, it would be:
$300USD = .05 * $100000 * (6/100) per year...
--- does that seem correct?

Also, do they charge for sea wall as well?