The Taylor River Flood Detention Dam, built in 1965, is the largest of its kind in New Zealand. It is 20 m high and involved 400,000 m³ of earthworks. The dam operates by detaining a one-day flood in the dam releasing its flow over two days, thereby reducing a 300 m³/sec flood peak to a 108 m³/sec peak.
The Wairau Diversion is also the largest of its kind in New Zealand. It is capable of carrying 3,000 m³/sec - 55% of the Wairau River's flow - on a direct, shorter path to the sea. Some 2,000,000 m³ of material has been removed from the diversion channel.
The Conders stopbank/groyne at Conders Bend near the Wairau (Renwick) bridge on State Highway 6 is vital in keeping the Wairau River out of the old Upper Ōpaoa River channel that leads to Blenheim.
Other river works data is:
Upper Ōpaoa /Roses Floodway
Lower Ōpaoa /Taylor Floodway
Lower Wairau Drainage Area