Influence of hydrological conditions and peat extraction operations on suspended sediment concentration and deposition in the East Branch Portage River, New Brunswick (Canada)

Peat extraction activities often generate sediments that can be transported into streams and rivers. These sediments have sometimes been shown to negatively affect the natural environment. This study investigated the effects of peat production on the East Branch Portage River, New Brunswick (NB), Canada. Relationships between discharge, precipitation and suspended sediment concentration (SSC) were analysed. The effect of sedimentation pond maintenance activities on SSC was also studied. Finally, the grain size distribution and organic content of deposited sediments were quantified at five sites downstream of the pond. Three water quality stations were monitored during the ice-free period in 2007 and 2008. Results showed that SSC was not significantly correlated with precipitation and weakly correlated with discharge, although some of the high SSC events were triggered by high discharge and precipitation. Pond maintenance alone failed to ensure optimal sedimentation pond efficiency. In 2008, SSC increased a few days after pond maintenance. The NB SSC 25 mg/L guideline was exceeded at all stations in both years. Analysis of variance results showed that there were significant differences in the grain size distribution of deposited sediments at the five sampled sites. Sand was the prevailing sediment type deposited downstream of the sedimentation pond.