Water gate at Hyrule castle.

At the north side of Hyrule castle the river ends at a huge gate, a Zora says higher up the river that you should take this river as it ends right up at Hyrule castle. Now if you take this river, you end up at this gate at the north side but you can't enter it from this side and so you have to go all over to the west or east side. This to me doesn't seem like 'straight' to the castle, or castle town for that matter. So the big question, can you open the big gate?