Causeway Closure Causes Problems
After over 50 years, the Petitcodiac River Causeway between Moncton and Riverview is set to be removed next year.
Since its construction in 1968, the causeway has been a major point of contention between many parties in the province. Originally constructed instead of a bridge due to fiscal pressure from the federal government, the causeway has severely sabotaged New Brunswick’s fishery industry, and presented a series of substantial challenges to the surrounding environment. The causeway’s gates prevent the annual salmon migration up the Petitcodiac, bad news for fisheries, who have been fighting to have the causeway removed for decades, and for the countless animals who rely on the annual salmon migration for food.
“In 1999, the battle to restore free flow to the Petitcodiac by opening the gates of the controversial causeway was entering its fourth decade,” said the Petitcodiac River Keeper. “By 2000, massive silt deposits covered 95% of the river near the City of Moncton and extended 35 kilometres downstream to Shepody Bay.”
An unforeseen consequence of the Causeway’s construction, as explained by the River Keeper, is that the Petitcodiac Causeway gates have greatly affected the flow of silt and sand from the river, causing problems beyond the Petitcodiac.
“Silt is a very fine soil particle that is easily carried away by water and wind and deposited into the river,” says the Sackville Rivers Association, “Silt decreases the stream velocity causing stagnant pools, fills in the space between and around river bottom cobble essential for healthly breeding and spawning grounds for fish, and smothers existing eggs and bottom-dwelling species.”
While the closure of the causeway is predicted to benefit the migration patterns of fish and wildlife in the Petitcodiac ecosystem, it is also on track to perpetuate the already alarming silt crisis for the surrounding rivers, like Sackville’s Tantramar River, by flushing the Petitcodiac silt into the connecting waterways.
Despite these negative impacts, the causeway has prevented the river’s water levels from devastating agricultural production along the Petitcodiac, a job previously done by the Acadian dykes. “The dyking of the marshes
converted the area into an expanse of flat land that is no longer subject to tidal flooding,” says Sabrina Hood, who has a masters degree in Planning from Dalhousie University. “The silty soils are poorly drained and have led to the formation of several shallow freshwater lakes, bogs, and rivers,” she says.
The removal of the causeway has occurred in three phases. The final removal completes the third phase, which is expected in 2021. Over the first two phases of the causeway’s removal, the Petitcodiac water levels and fish and waterfowl counts have all increased.
However, silt levels in Sackville’s Tantramar River are greatly influenced by the Petitcodiac, and by extension the health and safety of the river’s fish, invertebrates, waterfowl, and larger predators. Even over just the past week, Sackville’s silt level has risen noticeably, a continuation of the trend which began with the gradual removal of the Petitcodiac Causeway.
“Silt can affect salmon and trout populations directly and indirectly,” says the Sackville Rivers Association, “even small deposits of [silt] are dangerous. This is particularly true if silt is allowed to enter a stream over a prolonged period. There are really no safe levels of silt release.”
Though Sackville’s inland lakes and streams were formed as a result of Acadiam dykes, the Causeway process has been significantly different, most notably is the speed at which the silt is now transported. Dykes allowed a gradual landscape change, whereas the construction and deconstruction of the Petitcodiac Causeway have been relatively rapid events, not allowing wildlife to adjust to the change of their habitat. The speed at which silt is accumulating on Sackville’s shoreline is alarming and most certainly detrimental to the environment. However, the full impact of the Petitcodiac Causeway will not be known until next year when it is officially removed.