I think you did a pretty good job explaining it, irish, but it's the same way I would explain it.
If it still doesn't make sense to you, Imelda, just ask as many questions as you need.
The problem with that lake is that it is very large and they can't control the level of the water. If the water level is good, you can take an
ecv on the boat without a problem. If it rains a lot, the water level might be high compared to the dock (so the boat is floating high and an ecv won't be able to drive right on). If it's been dry, the boat will be floating too low compared to the dock. If you can't use the boat, there is always the alternative of the bus.