Lac Heney is located within the Regional Municipality of Gatineau. This lake overlaps the municipalities of Gracefield to the north and Lac Ste-Marie to the south. It extends over two townships, those of Northfield and Lac Ste-Marie. Lac Heney is primarily a residential and recreational area.
More than 300 shoreline owners currently live around Lac Heney. A few commercial activities take place around the lake, including five outfitters and a sawmill which is now closed.
Lac Heney is at an elevation of about 144 metres above sea level. This lake has a total surface area of 12.32 square kilometres and has a water volume of 172,300,000 cubic metres. Its water residence time is relatively long at 6.4 years, that is, it takes 6.4 years for the water volume to turn over once. Its average depth is 14 metres while its maximum depth is 32.5 metres. The Lac Heney watershed area is 64.8 square kilometre and is covered by a forest mainly consisting of leafy species.
Lac Heney is long and narrow, with a north-south orientation, like most lakes of glacial origin in Canada. The lake is protected relatively well from western winds. It is rather large and deep with only one trough.
The topography of the area is typically Laurentian: an undulating area of fairly level high ground broken by a large number of usually elongated hills, lakes, and plains of flood or river origin. Locally these hills may be oriented at random but in general their trend is north-northeasterly. However, in some places like Northfield Township the trend is directly northeast.
The average elevation of the hills is from about 270 to 370 metres above sea level and no hills in the area exceed 455 metres in elevation. The elevations of the depressions or low ground are between about 140 and 170 metres above sea level. Thus, relief is moderate in the area.
General Description of the Area Geology
Widespread discontinuous deposits of recent and surficial soil exist over much of the area. These deposits consist of soil derived from ancient rivers and lakes as well as glaciers and melting glacial outwash flows. This soil may generally be described as a matrix of gravel, sand, silt, clay mixed with cobbles and boulders, some of which could be very large; discontinuous surficial peat is also present.
Lac Heney rests on a geological basal layer or stratum that is unusual for the Canadian Shield. About 50 percent of the watershed rests on carbonated rocks consisting of calcareous marbles (those containing calcium carbonate), dolomitic marbles (those containing magnesian limestone), and impure marbles. These marbles are metamorphic rocks (those altered by extreme heat and pressure in their geologic history) of sedimentary origin. In the Lac Heney watershed the calcareous marbles predominate and are exposed extensively within the watershed; the dolomitic marbles are scarce and represent only about10 percent of the marbles in the area. Crystalline limestone (calcareous marble) and paragneisses (banded granular mineral rocks) are most widespread (see attached map). Crystalline limestone exists in all the low areas; most of the area lakes lie in crystalline limestone basins, the sole exception being Lac Victoria. Bare crystalline limestone (calcareous marble) exposures as seen particularly on the shores of Lac Heney and Thirty One Mile (Trente-et-un-Milles) lake show typical solution phenomena such as cavities and grooves.
Compared to other lakes in the Canadian Shield, the carbonated nature of the lake basin rocks gives a distinctive character to the chemical properties and biological communities of the lakes in this region. Their concentrations of calcium (10 to 30 milligrams per litre), magnesium (1 to 3 milligrams per litre), alkalinity (0.5 to 1.5 milli-eqivalents per litre), and pH (7 to9) are relatively high (pH is a measure of acidity and alkalinity of a fluid that is a number on a scale from 1 to 14, on which 7 represents neutrality while lower numbers indicate acidity and higher numbers indicate alkalinity). The dissolution of carbonated rocks and marbles may be an important natural source of phosphorus in the waters, since the slightly alkaline pH of the soil and water promotes the mobilization of phosphate in the watershed.
Lac Heney Water Sources
Apart from Lac Heney the watershed includes lakes Vert, Noir, Long, Desormeaux, Ruglis, a la Barbue, Chat Sauvage, and Partridge (Perdrix), the surface areas of which total 5.4 square kilometres. The principal lakes of the watershed (Heney, Desormeaux, Vert, Noir, and a la Barbue) are at almost the same elevation (144 to 145 metres above sea level).
A network of small surface and subsurface streams comprise the inlets and outlets to and from these watershed lakes. The water sources and discharges for these watershed lakes also include many artesian springs (springs flowing into the lakes from below the water surface) and leaks (direct links) into other water bodies.