I have noticed the gate was closed last year after the oil spill and they never reopened it. You can call the Willard bay office and ask them, the number is 435-734-9494. You can also send the park manager an Email, his address is jamesmorgan@utah.gov
The gate to the north dike parking area was closed due to vandalism of the parks service buildings. You now have to take the road to the right that goes down toward the airboat launch. Before you get all the way to the airboat launch there’s a road that turns back to the south towards the north dike and park at the end of that road and there’s a trail you walk up to get on the dike. Hope this helps.