Tidal Weir and Pipe Bridge
The weir is visible beneath the bridge. It keeps the water level higher and deeper on the far side but it also artificially creates two distinct ecosystems. Upstream is entirely freshwater, the downstream part (in the foreground) is tidal and so it varies in salt content depending on the tides downstream.
The coloring of the bridge may be to warn boaters away. I don't believe the weir has a lock or boat lift so that boats can only move between either side of the weir by portage.
Tidal Weir and Pipe Bridge
The weir is visible beneath the bridge. It keeps the water level higher and deeper on the far side but it also artificially creates two distinct ecosystems. Upstream is entirely freshwater, the downstream part (in the foreground) is tidal and so it varies in salt content depending on the tides downstream.
The coloring of the bridge may be to warn boaters away. I don't believe the weir has a lock or boat lift so that boats can only move between either side of the weir by portage.