1959 saw many changes, as the Upper Holland Valley Conservation Authority requests the provincial government to pass legislation to control tree-cutting on private and public property.

An Emergency Flood Fund was established in 1967, and Centennial tree planting swept across the entire watershed, including reforesting the Scanlon Creek Conservation Area.

The Conservation Authority added a number of properties to its natural heritage network in the 1980s including: In 1981, the provincial Ministry of the Environment initiated a new study to identify and measure sources of phosphorus entering Lake Simcoe, and to recommend actions needed to reduce these inputs.

In 1985, LSEMS identified phosphorus inputs from both urban and rural sources as the leading cause of the decline of Lake Simcoe's water quality and coldwater fishery.

The LSEMS Team seeks provincial funding in 1986 for programs and services aimed at reducing the amount of phosphorus entering water courses from both urban and rural sources to stop contamination and deterioration of the lake.

Local youth participate in the "Yellow Fish Road" program to promote the responsible disposal of household hazardous waters, and 1,500 people hear how they can help save Lake Simcoe.

The following year, the LSRCA establishes a new collaborative partnership with the Federal Government's Department of Fisheries and Oceans to protect and enhance Lake Simcoe and its fish habitats.

In 2001, the LSRCA began to deliver its programs and services to parts of York and Durham Regions, the City of Kawartha Lakes, and Simcoe County.