Mactaquac Ecosystem Study

Mactaquac Generating Station, a 672 MW run-of-the-river hydroelectric facility, was constructed in 1968 on the main stem of the Saint John River (SJR), New Brunswick, Canada and is owned and operated by NB Power. The facility is expected to reach the end of its service life by 2030, when the powerhouse and spillway will no longer be viable because of an alkali-aggregate reaction with the concrete. NB Power needs decide on a preferred option for the future of Mactaquac Generating Station by 2016. Options identified for the future include repowering the station with a new powerhouse and spillway, rebuilding the spillway only, or removing all parts of the station. The decision will be based on a combination of economic, environmental, and social consequences ( 

To make an informed, science-based decision for a preferred option, NB Power has engaged the Canadian Rivers Institute to design a large multidisciplinary aquatic ecosystem study to support their decision making process and subsequent regulatory requirements.




The Mactaquac Aquatic Ecosystem Study (MAES) is a planned, whole-river ecosystem study and manipulation. It begins with a multi-year assessment of the structure and function of a large river ecosystem, followed by a manipulation of flow, sediment load, and thermal regime with consequential effects on the ecosystem, and then a multi-year period to monitor the recovery to a new river state.

The manipulation will induce either an acute, major perturbation with long-term effects, i.e., removing the station and restoring the river to a free-flowing form, or a minor, lesser stress event created by the multi-year, re-construction of the station, but chronic in that the generating station and hydroelectric-related issues persist. A comprehensive study and planned manipulation of an ecosystem of this scale is one of the largest freshwater experiments attempted worldwide.

MAES takes a phased approach to address the scientific challenges for the future of the Mactaquac station. Phase I (2014 - 18) is the assessment of the key baseline environmental conditions and description of the environmental challenges and opportunities for either replacing or removing the station. Currently, 29 separate project components are planned, which are collectively described within three separate study themes.



View MAES reports here
August 29, 2016: 
MAES interactive Story Map is released 
May 9, 2016:  Canadian Rivers Institute student researchers hit the water to answer questions about river health 
May 5, 2016:  The Canadian Rivers Institute and NB Power’s Mactaquac Project
May 1, 2016: Check out CRI's online data and GIS depository live
December 19, 2015:  Check out the MAES Summer 2015 team in action!
November 4, 2015:  The MAES Sediment Team and their beloved cores from the Mactaquac Headpond


This project could not take place without the valued financial contribution from the following organizations:


Important partners on this project include: