Lagan Weir
The 928th tallest dam in the world
The Lagan Weir, in Belfast, Northern Ireland, crosses the River Lagan between the Queen Elizabeth Bridge and the M3 cross-harbour bridge. Prior to the building of the weir, the river would be subject to tidal fluctuations, and low tide would expose mudflats, which were unsightly and emitted a strong odour, particularly in the summer months. Opened in 1994, the weir was seen by the Laganside Corporation as a catalyst for its redevelopment projects and was judged to be the "centrepiece" of that effort. The weir also incorporates a footbridge.
Dam data from Wikidata (CC0) plus curated additions. Summary from Wikipedia (CC BY-SA).