Miramichi River
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- This article is about the river in New Brunswick. For more information about the communities which comprise the Miramichi region, see the separate article on the Miramichi River valley.
The Miramichi River is a Canadian river located in the east-central part of New Brunswick. The river drains into Miramichi Bay in the Gulf of St. Lawrence.
The name may derive from the Innu word for "land of the Mi'kmaq".
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Geography
The Miramichi River watershed drains a territory comprising one-quarter of New Brunswick's territory, measuring approximately 13,000 kmē of which 300 kmē is an estuarine environment on the inner part of Miramichi Bay. The watershed roughly corresponds to Northumberland County, but also includes sections of Victoria County, Carleton County, and York County and smaller parts of Gloucester County and Sunbury County.
The Miramichi River meander length measures approximately 250 km and is comprised of two important branches, the Southwest Miramichi River and the Northwest Miramichi River, each having their respective tributaries. Tides reach upriver in the Miramichi system to Sunny Corner, NB on the Northwest Miramichi and to Quarryville, NB on the Southwest Miramichi - a distance of approximately 70 km inland from the Gulf of St. Lawrence. The two branches combine at Newcastle, NB where the river becomes navigable to ocean-going vessels.
The estuarine portion of the Miramichi River downriver from Newcastle, NB flows through a drowned river valley. Sea level rise in Miramichi Bay has flooded the mouth of the Miramichi River with saltwater. The estuary comprises the inner portion of Miramichi Bay and is protected from ocean storms in the Gulf of St. Lawrence by barrier islands. The estuary is significant in that it is a highly productive ecosystem, despite its relatively small size. The estuary receives the freshwater discharge from the Miramichi River and its tributaries, mixing with organic materials from the surrounding shorelines and the saltwater inundation from the Gulf of St. Lawrence, itself an estuary and the largest on the planet.
The estuary is a highly dynamic environment, ranging from the high outflows of freshwater during the spring freshet, to the low outflow and rising saltwater content during the summer period, to fall ocean storms and nor'easters which reshape the barrier islands and the old river channel which forms the navigation channel for ocean-going ships heading to ports at Chatham, NB and Newcastle, NB, to the winter covering of sea ice which encases the entire estuary. The inner bay measures only 4 m deep on average, with the navigation channel measuring only 6-10 m, resulting in significant warming of estuarine waters during the summer months. The diurnal tide cycle ranges only 1 m on average.
Tributaries
Important tributaries include:
Miramichi River
Geology
Rising in the Silurian and Ordovician rocks of the Miramichi Highlands, an extension of the Appalachian Mountains, the tributaries of the Miramichi River flow eastward into the New Brunswick Lowland, which dominates the eastern and central part of the province along the Gulf of St. Lawrence.
Erosion has created the "Miramichi River valley" (also shortened to just "Miramichi valley"), through which the Northwest and Southwest Miramichi rivers flow. Throughout the course of both branches to Newcastle, NB, they are framed by heavily forested low hills. The highest peak in the Miramichi River watershed is Big Bald Mountain, measuring only 672 m above sea level.
Soils in the Miramichi River watershed are typically acidic with shallow topsoil, lending to poor suitability for agriculture. The shorelines of the estuarine portion of the Miramichi River exposes newer rocks belonging to the Carboniferous era and underlay the sandy topsoil, however some coastal land is low lying and suffers poor drainage. Sandstone rocks are visible along the river banks.