The Grand River Conservation Authority is a corporate body governing the cooperative management of the Grand River watershed and its natural resources by municipalities, landowners and other organizations within the watershed. Formed in 1966 following the merging of the Grand River Conservation Commission and the Grand Valley Conservation Authority, the GRCA's origins date back to the 1930s.

In the early 1800s, the Grand River was a source of transportation, power and water for local communities. Settlement led to deforestation, intensive farming and urbanization, which began to hinder the natural cycles of the river. By the 1930s river conditions had become so severe that annual floods, drought and pollution were affecting public health and the economic development of the communities up and down the Grand.

Sponsored by the Grand Valley Boards of Trade and modeled on the fledging Tennessee Valley Authority in the United States, the "Grand River Conservation Commission Act" was passed by the Province of Ontario in 1932. The Grand River Conservation Commission (GRCC) was the first watershed management agency in Canada when it received its formal Letters Patent in August, 1934. The formation of the GRCC marked the first time local municipalities had banded together to address water management issues on a watershed scale. The founding partner municipalities were Brantford, Galt, Kitchener, Fergus and Caledonia. William Philip of Galt was the first chairman, and the commission's head office was in Brantford. Other municipalities soon joined the partnership.

In 1942 the commission completed the Shand Dam near Fergus, the first dam in Canada built for flood control, water supply and water quality purposes. This was followed by the Luther Marsh Dam in 1954 and the Conestogo Dam in 1958. Funding was shared between the federal and provincial governments, (each paid 37.5 per cent) and the local municipalities paid 25 per cent. The GRCC also planted more than two million trees and undertook some of the province's first large scale reforestation projects. The success of the commission, its watershed scope and municipal partnership model led to the Guelph Conference on Conservation in 1941, and the Conservation Authorities Act of Ontario in 1946. This new act led to the creation of 36 conservation authorities across the province.

In 1948, the Grand River watershed municipalities formed their own Grand Valley Conservation Authority (GVCA) under this new act. This new agency had extended powers in the 1950s, which allowed it to acquire many wetlands, forests and natural areas in the watershed. The GVCA also acquired park land for camping, swimming, fishing and canoeing including what would become the Elora Gorge, Rockwood, Pinehurst Lake and Byng Island.

Over time the GVCA's objectives began to parallel those of the GRCC and the two agencies merged in 1966 to form the Grand River Conservation Authority (GRCA), which operates under the Conservation Authorities Act of Ontario. As a corporate body, through which municipalities work cooperatively to manage the water and natural resources in the watershed for everyone's benefit.