I talked to the office about the blockage. It's been done by the state. They apparently were concerned about some rebar sticking out at the bottom of the ramp that would cause tire damage.

They have plans to repair/enhance the ramp next spring, when the water drops. Apparently there wasn't money to do that this year.

I think the ramp could be temporarily fixed with the addition of about 50 bucks worth of concrete tiles and a little mortar. I am going to contact the person in charge of the access area and see if they would be agreeable to a few private citizens undertaking a temporary repair. I'll post the results of that conversation when it happens.