What is the name of the fixed structure just west of the mouth of the Moira River?

The fixed structure located just west of the mouth of the Moira River is a highway bridge. Its significance stems from its role in facilitating transportation and connectivity for vehicles traveling across the area. Bridges are critical infrastructure elements that provide safe passage over obstacles like rivers, making them essential for both everyday transport and emergency routes.

While the other options present different types of facilities, they do not accurately describe the structure in question. A water treatment plant focuses on processing and purifying water, which is not the function of a bridge. A railroad bridge, while also serving a transportation purpose, specifically caters to rail traffic rather than road vehicles. A power plant generates electricity and does not serve as a transport conduit across the river. Therefore, the identification of the highway bridge reflects an understanding of infrastructure and its relevance to the particular location near the Moira River.