Bouleau River


The Bouleau River is a salmon river in the Côte-Nord region of Quebec, Canada.
It drains an area of the Canadian Shield plateau into the Gulf of Saint Lawrence.
The terrain includes large areas of bare rocks, as well as forests dominated by black spruce and balsam fir.

Location

The Bouleau River rises on the Laurentian Plateau and empties into the Gulf of Saint Lawrence about east of Sept-Îles.
Its source is to the north of Lake Bigot, west of Lake Nipisso.
It rises at an elevation of, flows south for about, and has two major tributaries.
The watershed covers.
The bedrock is Precambrian, covered in typical boreal vegetation.
The mouth of the Bouleau River is in the municipality of Rivière-au-Tonnerre in the Minganie Regional County Municipality.
The drainage basin covers parts of two regional county municipalities, within which it covers parts of four smaller administrative units:
The name "Bouleau" means birch, a tree that grows in cold and temperate regions, with white bark and small leaves, whose wood is used in carpentry, cabinet making and for the manufacture of paper.
The name was made official on 5 December 1968.

Terrain

The bulk of the watershed is on the rugged Laurentian Plateau, with elevations of.
The highest point is in the northeast, at.
The plateau has hills or ridges with steep slopes and is cut by valleys whose sides are over deep in places.
Further south there is a piedmont sector about wide with altitudes from.
The piedmont has rounded hills and wide valleys.
The coastal plain between the piedmont and the Gulf of Saint Lawrence is no more than in width.
It is relatively flat, sloping from inland down to along the sea, where the shoreline is formed by an escarpment almost high.
The bedrock of the watershed, which is mostly exposed in the northern part, consists of deformed magmatic rocks.
The north is dominated by gabbro, pyroxenite, troctolite and amphibolite.
The south has granite, pegmatite and migmatite.
The rocks in the south are partially covered by glacial till that is rarely more than thick.
The coastal fringe shows the influence of the postglacial Goldthwait Sea, which left large quantities of marine clay and silt sediments.
These have often been covered in sandy deltaic sediments.
The valley of the Bouleau holds glaciofluvial sediments.

Environment

The Matamec weather station, west of the river, records an annual average temperature of and average annual rainfall of.
A climate model indicates that annual average temperature would be in the northern part of the watershed, while average annual rainfall would be about throughout the watershed.
A map of the ecological regions of Quebec shows the Bouleau in sub-regions 6j-S, 6j-T and 6m-T of the east spruce/moss subdomain.
Forest cover consists of black spruce and balsam fir, with black spruce dominant on the coastal plain and north of the watershed, and mixed spruce/fir in the central region.
There was a large infestation of hemlock looper moths in the late 1990s and early 2000s that significantly damaged the fir trees.

Hydrology

The watershed is very elongated, along a north–south axis of.
Its greatest width is in the center section, where it reaches.
About 6.85% of the basin is covered by water bodies, the largest being Lake Bigot in the north with an area of.
Due to the sloping terrain in most of the basin, wetlands such as ombrotrophic peatlands cover only 0.46% of the basin.
The network of streams and rivers is angular, conforming to fractures in the hard bedrock, with straight segments between right-angled forks.
In the plateau the rivers flow through narrow V-shaped valleys with very steep slopes.
In the piedmont the valleys have the U-shaped profile typical of glacial valleys, and the rivers wander through the glaciofluvial deposits.
The Bouleau River has a length of and vertical drop of.
The most important tributary is the Chiskal River, which drains the northwest of the basin.
The lowest part of the Bouleau River flows in a straight line through the coastal sediments in a narrow valley with sides of over, emptying into a wide estuary with brackish water, partially blocked by a ridge at its entrance with an opening wide.
Tides reach inland from the mouth to about.
About above the head of the tidal area there is a long stretch of powerful rapids that may block the further upstream progress of Atlantic salmon.
Below these rapids the river has a gradient of.
There are a few pool areas, but this section mainly consists of rapids flowing over gravel, large rocks and bare rock.
The annual average discharge is, varying from.

Fish

The river holds anadromous Atlantic salmon , brook trout, and less commonly American eel and three-spined stickleback.
There are also alewife, Atlantic tomcod and rainbow smelt.
The upstream section of the river is considered an exceptional habitat for young salmon.
However, the large rapids from the mouth limit their migration.
In May 2015 the Ministry of Forests, Wildlife and Parks of Quebec announced a sport fishing catch-and-release program for large salmon on sixteen of Quebec's 118 salmon rivers.
These were the Mitis, Laval, Pigou, Bouleau, Aux Rochers, Jupitagon, Magpie, Saint-Jean, Corneille, Piashti, Watshishou, Little Watshishou, Nabisipi, Aguanish and Natashquan rivers.
The Quebec Atlantic Salmon Federation said that the measures did not go nearly far enough in protecting salmon for future generations.
In view of the rapidly declining Atlantic salmon population catch-and-release should have been implemented on all rivers apart from northern Quebec.
In 2017 all salmon, large and small, had to be released on the Malbaie, Pigou, Bouleau, Magpie, Coacoachou, Nétagamiou, Little Mecatina and Véco rivers.
Only young salmon could be retained on 51 rivers, and limited retention of large salmon was allowed on 19 rivers.