[3] A landfill on Guelph's York Road was operated on the banks of the Eramosa until it was closed in the early 1960s, when it was covered with soil and transformed into an urban park.

The Guelph Boating Club was founded in 1870 when the success of Saint John's Paris Crew made rowing a popular activity throughout Canada.

[5] By 1873 the river was a hotbed of local activity, with one site known as "Paradise" hosting facilities such as swings, Picnic areas, and a shooting range.

An offshoot of the Guelph Boating Club opened Victoria Park on the banks of the Eramosa River in 1886, and the site soon became a popular summer getaway for boaters and campers.

Charles Ambrose Zavitz, a professor at the Ontario Agricultural College, identified the Paradise area as being ideal for small-scale farming, as it was located on a floodplain too marshy for any agriculture which required wagons or other machinery,[3] and suggested it as a place model prisoners could engage in penal labour and develop a prison farm.

[6] The first structures at the Ontario Reformatory was built on the banks of the Eramosa River in 1909 and received its first fourteen prisoners (called "trusties", as they were trusted to work without armed guards or shackles) in April 1910.

The cornerstone of the Ontario Reformatory was laid down by Premier James Whitney on 25 September 1911, who ceremoniously crossed a concrete bridge built by the inmates just a year earlier before arriving at the prison.

A. J. Casson, a member of the famed Group of Seven painters, visited the site at one point to paint the mill and the Eramosa River.

[10] Local environmentalist Bryan McNeill brought the issue to public attention after recovering thirty-five garbage bags filled with nurdules, causing the Ministry of the Environment, Conservation and Parks (MOE) to launch an investigation in September 2017 and confirm PDI as the source of the beads.

In response, PDI consultants surveyed 3.5 kilometres (2.2 mi) of the Eramosa River's northern bank and cleaned up thousands of nurdules.

[12] Also in early 2019, the Eramosa River Conservation Corridor was created by the rare Charitable Research Reserve after the organization purchased 87 acres (0.35 km2) of riverfront property in Rockwood.

[3][15] As little boat traffic passed along this point of the Eramosa River, Wellington County engineer A. W. Connor and Italian-Canadian mason Charles Mattaini built the bridge low over the water.

The Guelph Dam, located at the mouth of the Eramosa, also regulates the flow and depth of the river; when open, the water level can drop to as little as 6 inches (15 cm).

Relative to other bodies of water in the Grand River watershed, the Eramosa has very low levels of phosphorus, nitrogen, and chloride.

[3] Hundreds of species of birds are also endemic to the region, with gulls and passerines being the most common types sighted around the Eramorsa-Speed River confluence.

[17][22][20] The largely-undeveloped upriver sections of the Eramosa River serve as a natural refuge for a number of at-risk and endangered species.

[13] Bobolinks, golden-winged warblers, eastern wood pewees, and barn swallows roost in the area, but are threatened elsewhere by habitat loss.

The park represents the greatest concentration of glacial landforms along the Eramosa River, and features opportunities for spelunking in its many limestone caves.

When the Guelph Dam is open, water levels in the river become so low that paddlers are forced to frequently disembark and drag their canoe across its shallowest sections.