twin bridges connecting Christchurch with the region north of the Waimakariri River via State Highway 1. It is located downstream from the Waimakariri Gorge Bridge. As part of the Christchurch Northern Motorway, each bridge was widened from two to three lanes during 2020, plus a cycleway added. Main North Road bridge Just downstream from the state highway bridges is the Main North Road bridge, often referred to as the Old Waimakariri Bridge. This two-lane traffic bridge does not cater for walking or cycling. Main North Line bridge #17 Immediately downstream from the Main North Road bridge, the Main North Line crosses the river. Kiwirail records this bridge as number 17 on its bridge asset list. Ecology As one of the largest rivers on the Canterbury plains, the Waimakariri is an important habitat for wildlife, including many endangered species of plants and animals. The dry sections of riverbed are home to black-fronted terns, where braids in the river provide a natural barrier to predators. The river and its tributaries are home to native species, including crayfish / kōura, New Zealand longfin eel, short-finned eel, lamprey and many species of invertebrates. The river is one of the few remaining habitats for the critically endangered Canterbury mudfish (kowaro), which previously inhabited wetlands across the Canterbury plains, while a portion of its riverbank is home to one of only two known remaining populations of Olearia adenocarpa. Introduced fish are common along the entirety of the Waimakariri River, making the river a popular location for fishing. As with most of New Zealand, this primarily includes brown and rainbow trout, as well as Chinook salmon (Oncorhynchus tshawytscha). The salmon population dates to the early 1900s, when they were introduced from California, and results in large salmon runs near the river mouth in summer. Development In 1923 the river was mainly investigated for a hydroelectric dam to supply electricity to Christchurch. It received support from the community but the dam was never built since the Government offered inexpensive electricity from the Lake Coleridge scheme. The Central Plains Water Trust is proposing to take of water from two points on the Waimakariri River as part of the Central Plains Water enhancement scheme. Pollution In 2007 the Waimakariri was ranked as one of the ten most polluted of the larger rivers in New Zealand. Some of the pollution was caused by liquid wastes from industries such as a meat