Restoring Full Tidal Flow

The Petitcodiac River Project consists of replacing the causeway with a 280 m bridge in order to achieve maximum recovery of the Petitcodiac River system. Engineers and hydrologists often set as an objective the restoration of full tidal flow when establishing parameters to restore river systems.In the case of the Petitcodiac, hydrological estimates suggest that an opening of between 250 and 280 m is needed in the 1-km long causeway structure in order to restore full tidal flow to our river. Restoring full tidal flow is expected to restore as much as 80% of the river channel functions (approximately 90% of the river channel is presently filled in the Moncton area), creating the conditions necessary to restore fish passage and the unique Petitcodiac River tidal bore.

Phased Approach

In accordance with the Environmental Impact Assessment approval, the project will be implemented in three phases:

Phase 1: 2008-2010

This phase involves preparatory work before opening the causeway gates including:

- Erosion protection at locations downstream of the causeway (including the former Moncton Landfill);

- Drainage improvements at the causeway traffic circle to prevent flooding, and

- Dyke and aboiteaux construction upstream of the causeway to protect agricultural land.

Phase 2: 2010-2012

This phase begins with the opening of the causeway gates in the spring of 2010.  The gates will remain open for a period of two years to allow monitoring of the Petitcodiac River both upstream and downstream of the causeway.

Phase 3: 2010-2013

This phase involves construction of the 280 m bridge to replace the causeway structure. The bridge will take a few years to build and is expected to open to traffic in 2013.

Project Costs

The total costs of implementing the three phases of the project are approximately $68 million.

Project Benefits

Benefits associated with restoration of full tidal flow to the Petitcodiac River are predicted in the areas of eco-tourism (tidal bore observation and day adventure activities on the river, infrastructure development and fishing (commercial and recreational). Total projected benefits would require a more detailed cost-benefit analysis and projections for the recovery of fish stocks in the river system.

Update – March 2014

Today, almost four years after the opening of the gates, even if the width of the opened causeway gates represents only a small portion of river’s original width, the water flow has had a dramatic effect. Sediment particles accumulated in the bottom of the river and on the banks for more than 40 years, which had resulted in mud, were lifted and moved twice a day. This resulted in greatly expanding the river while gradually restoring the tidal bore to its former glory.

However, the fight is not over yet. Petitcodiac Riverkeeper continues to work to ensure that the provincial and federal governments uphold their commitments regarding the next phases of the project, including replacing the causeway with a bridge in order to allow the river to flow much larger in width again.

Although the river is doing increasingly well since the opening of gates, expanding and regaining its natural flow downstream, it is shrinking more and more upstream. The tidal control structure is contributing to this problem. Visit the Riverwatcher’s blog page to find out why.