The Ganaraska Region Conservation Authority's overall goal is the conservation, restoration, development, and management of natural resources on a watershed basis while providing for the public enjoyment of the lands it oversees.

The Ganaraska Region Conservation Authority (GRCA) was formed in October 1946 under the Conservation Authorities Act and is one of the oldest conservation authorities in Ontario.

The watersheds of the GRCA covers an area of 361 square miles from Wilmot Creek in Clarington to east of Cobourg from the south shore of Rice Lake down to Lake Ontario. This area includes seven municipalities in whole or in part: Township of Cavan Monaghan, Town of Cobourg, Township of Alnwick/Haldimand, Township of Hamilton, Municipality of Port Hope, City of Kawartha Lakes, Municipality of Clarington. The Ganaraska Forest is at a pivotal moment in its history. The largest block of continuous forest in Southern Ontario, it is a huge expanse of 11,000 acres that represents one of the most successful conservation projects ever undertaken in central Canada.

Local History of Watershed Planning and Management (1936 to 1970)

The early days of conservation began in the late 1800s with the realization that ongoing deforestation was having devastating environmental, social and economic impacts. Many individuals, community groups and organizations were ringing alarm bells at local and regional levels. Numerous pieces of legislation, policies, and programs late 1800s and early 1900s in effort to improve land management practices, protect existing were tested and implemented through the natural features, and restore degraded landscapes. However, one of the most instrumental additions to the conservation movement was the passing of the Conservation Authorities Act in 1946.

The Conservation Authorities Act came to be in part by a group of conservationists who met to discuss shared conservation concerns at the Guelph Conference in 1941. In order to build a case for conservation in Ontario, members of the Guelph Conference decided that a pilot survey should be carried out and funded by the provincial and federal governments. The selected survey site was the Ganaraska River watershed, with the survey being conducted from 1942 to 1943. The Ganaraska River watershed survey, the work carried out by the founding conservation associations, and the Conservation Authorities Act paved the way for the creation of the 36 Conservation Authorities that exist today.

 

 

The resulting report from the pilot study entitled "Ganaraska Watershed: A study in land use with recommendations for the rehabilitation of the area in the post war period” by A.H. Richardson, provided the necessary plan for managing the Ganaraska River watershed. Under the Conservation Authorities Act, the Ganaraska River Conservation Authority was formed on October 8, 1946, making it one of the first Authority’s formed. While other Conservation Authorities were awaiting a conservation report from the Conservation Branch, the Ganaraska River Conservation Authority began implementing the recommendations from the Ganaraska Watershed report.

Locally, effects of land use changes and land cover were being realized in other watersheds. The Ontario Forestry Branch published A Study in Forest Conservation and Land Use on the headwaters of Wilmot Creek in 1940, two years before the survey work of the Ganaraska River.

In 1962 and under a requested expansion by local municipalities, Wilmot Creek, Graham Creek, and smaller streams flowing to Lake Ontario in the west were added to the responsibly of the Ganaraska River Conservation Authority. With this expansion, the Authority was re-named the Ganaraska Region Conservation Authority (GRCA). In 1970 Gage Creek, Cobourg Creek and streams flowing to Lake Ontario and Rice Lake in the east were added. With the final expansion, the GRCA covers an area of 935 square kilometers from Wilmot Creek in Clarington to east of Cobourg from the south shore of Rice Lake down to Lake Ontario. This area includes seven municipalities in whole or in part: Township of Cavan-Monaghan, Town of Cobourg Township of Alnwick-Haldimand, Township of Hamilton, Municipality of Port Hope, City of Kawartha Lakes, Municipality of Clarington.

History of The Ganaraska Forest (1800 to 1997)

Early European colonization and settlement changed the natural landscape and the flow of water in significant ways, and much of the changes was due to the principal source of revenue in the area being distilleries and the lumber trade. Many villages along the Ganaraska River and elsewhere had developed specific industries that relied on waterpower from local rivers such as sawmills, grist mills, cider mills, woolen mills, carriage factories and chair factories.

The era of environmental and community decline was significantly felt in the 1880s through to the 1900s. The loss of the big timber trade in the lower Ganaraska River had occurred by the 1880s and the upper reaches by the 1890s. The blow to the local timber industry was the effects of the McKinley Tariff of 1890 which saw a tariff of almost 50% applied to almost all commodities exported from Canada to the United States. At this point, much of the land within the GRCA, especially along the Oak Ridges Moraine was severely deforested, and turning into wastelands.

In 1944, the Ganaraska Watershed: A study in land use with recommendations for the rehabilitation of the area in the post war period was published and outlined a set of watershed management recommendations. One of the recommendations was the reforestation of 8,000 hectares (20,000 acres) in the northern section of the Ganaraska River watershed.

At the first meeting of the Ganaraska River Conservation Authority in 1946, a draft of a new Forestry Agreement between the Authority and the then Department of Lands and Forests was submitted and subsequently approved. This approval allowed for the purchase of nine parcels of land totaling 460 hectares (1,150 acre), and on May 141947, the first tree was planted, which began Ontario’s first Authority Forest. Reforestation was accomplished through the hard work and dedication of the local community, including veterans who returned from WWII. The land on which the reforestation occurred was acquired from local property owners by the GRCA, and lands transferred from local municipalities. By 1991 the total amount of land acquired by GRCA was 4,200 hectares (10,400 acres). Reforestation was necessary on fifty per cent of this land. In April of 1997, the Ganaraska Region Conservation Authority became completely responsible for the management of the Ganaraska Forest, which up to that point was carried out by the Province of Ontario.

History of Flooding on the Ganaraska River

Throughout history the Ganaraska River has experienced flooding at varying degrees Between 1848 and 1937, 34 flood events were recorded by local residents and the media.

A relationship between forest cover in the watershed and the frequency and severity of floods has been noted. The principal factors contributing to increases in the frequency of floods included deforestation within the watershed, and drainage and development for agricultural purposes.

Reforestation of large areas was therefore proposed in The Ganaraska Watershed report to reduce the frequency of floods and improve summer flow conditions.

The vision of flood reduction coinciding with reforestation was slowly realized throughout the mid-1900s, as the forests in the headwaters began to augment surface water flows and groundwater infiltration. Flood control again increased in the province after Hurricane Hazel struck central Ontario in 1954, killing 81 people and leaving thousands homeless. Although devastating effects were felt in Toronto, Port Hope received little damage. However significant flooding still occurred through the 1950s, 1960s and 1970s.

On March 21, 1980, the flood of the century hit the Ganaraska River. It was caused by rainfall that was not particularly severe by yearly standards (5-year event), but which was relatively severe for the month of March (50-year event). Rainfall on frozen ground caused little or no infiltration, and it was concluded that the 1980 flood has a recurrence interval of 100 years.

This event caused the Ganaraska River to experience a flow of 421 cubic metres/second, causing 66 acres of downtown Port Hope to be flooded with water depths to 1.5 meters (m) and velocities sufficient to knock down building walls.

To mitigate further flood events like what was experienced in 1980, channelization of the river through downtown Port Hope was proposed and constructed. The river was widened and deepened over approximately 1,000 metres to allow greater capacity of flow to move through the town. Since channelization has occurred, downtown has not experienced significant flood events, although localized seasonal flooding does occur throughout the watershed.

Learn more about the 1980 Ganaraska River Flood

Interesting Reading Material
Arthur Herbert Richardson. 1974. Conservation by the People: The History of the Conservation Movement in Ontario to 1970. University Toronto Press.
Ganaraska Region Conservation Authority. 1981.35 Years of Watershed Management. Port Hope, ON.
Ontario Ministry of Natural Resources. 1986. Evergreen Challenge: The Agreement Forest Story. Toronto, ON