This valley is served mainly by rue Saint-Louis which goes up on the east side of this watercourse and by rue Labranche which goes up in part on the west side. Forestry is the main economic activity in this valley; recreational tourism, second. Because of its altitude, the surface of the upper part of the Île river is generally frozen from the end of November to the beginning of April; however, safe circulation on the ice is generally done from mid-December to the end of March. The lower part of the river course has a freezing period of about a week less than the upper part. The water level of the river varies with the seasons and the precipitation; the spring flood occurs in March or April.
Geography
The "rivère à l'Île" rises from a Dame Deux lake located in the north-central part of Château-Richer. This lake receives by its north shore a stream. During the 1920s, log drivers transported wood cut into logs on this lake in winter in order to divert it in the spring by the current from this river to the Montmorency river. The mouth of the lake of Dame Deux is located at:
south-east of the "Tour-du-Nord" which was used by the fire guards;
northwest of the northwest shore of the St. Lawrence River.
From the mouth of the head lake, the "rivière à l'Île" descends on, with a drop of according to the following segments:
to the south in a deep valley crossing three series of rapids and passing between two mountains, to Fiset stream ;
to the south in a deep valley between the mountains, crossing several series of rapids, up to the West Arm from the River to the Island ;
south-east to the outlet of Lac Thibeault ;
towards the south by forming on a segment the limit between Stoneham-et-Tewkesbury and Sainte-Brigitte-de-Laval, bending again towards the south- is to bypass an island having a length of, up to a road bridge on rue Pascal;
towards the south-east by crossing the village of Sainte-Brigitte-de-Laval.
The mouth of this river is located about 2.5 km northeast of the center of Sainte-Brigitte-de-Laval, a city located about twenty kilometers northeast of Quebec. From the confluence of the "rivière à l'Île" the current flows over generally towards the south by the course of the Montmorency River, to the northwest bank du St. Lawrence River.
Toponymy
The main course of this river was formerly designated "Saint-Adolphe River". While the upper segment was designated "Saint-Adolphe Nord-Est river". The toponym "Rivière à l'Île" refers to the peninsula bounded on the west side by the Île river and on the East side by the Montmorency river. This point of the mouth of the Île river has a length of in a north–south direction. Formerly, it was considered an island during the great floods. This point has a uniform part where the Laval-Nord residential sector has been developed. The Île river includes another island with a length of located downstream from the outlet of Lac Thibeault. The eastern channel, bypassing this island has two dams each forming a small reservoir.. Since December 13, 1996, the toponymic designation "Rivière à l'Île" has also applied to the bed of a stream to the east, which was officially called "Bras du Nord" from February 4, 1982. The toponym "Rivière à l'Île" was formalized on December 13, 1996 at the Commission de toponymie du Québec.
