Litke says part of the reason for the poor ratings is decades of wear and tear, but also to now-higher engineering and environmental standards. They are the primary defence from major damage in the region's floodplain, which includes virtually all of Delta, Richmond, Pitt Meadows and Kent, and much of Surrey, Port Coquitlam, Abbotsford and Chilliwack. Since the late 19th century, dikes have been installed throughout the Lower Mainland. (Fraser Basin Council) Many municipalities under floodplain
The vast majority of Richmond, Delta, Pitt Meadows and Kent are under the region's flood plain, and require dikes to be protected and livable year-round. With multiple atmospheric rivers forecasted for the Lower Mainland this weekend, the stability of those dikes - and why so many are considered in poor condition - is once again under examination. "We've always known the Fraser can generate large floods, but we also need to look ahead, and not increase our exposure and vulnerability over time," said Steve Litke, a senior manager with the Fraser Basin Council, which helps educate organizations and governments about healthy watersheds across southwest B.C. Upgrading them would cost $865 million, according to a separate 2020 report to the province.
In addition, half of the province's 178 orphan dikes - that are not under any government's jurisdiction - were in "poor or failing" condition. The conclusions were grim: 71 per cent of them could be expected to fail during a significant "design event," while none of the dike segments met seismic standards over their entire length. The report looked at dikes that extend for over 500 kilometres, comprising around half of the total length of those in the province. The dike was "too low," "substandard" and "likely needs to be updated" according to a report, written by Northwest Hydraulic Consultants for the Ministry of Forests which looked at 74 dikes across the Lower Mainland.
The breach of a dike in Abbotsford, B.C., that contributed to disastrous flooding throughout the Sumas plain was anticipated in a 2015 review for the provincial government.