Impact of the Nelson Aggregate quarry expansion on fish populations
The proposed extraction below the water table will disrupt flows to creeks and ponds that currently serve as fish habitat. According to the JART, surface water on the proposed extraction area currently drains in three directions: north into the existing quarry; southeast into the east arm of the Mount Nemo Tributary; and southwest in the west arm. The northeast corner drains to Bronte Creek and the rest of the property feeds Grindstone Creek. Bronte and Grindstone Creeks are both quarternary watersheds that contribute to the Credit River-16 Mile Creek tertiary watershed.
Grindstone Creek originates above the Niagara Escarpment in Flamborough. It drains an area of 90 square kilometres making it one of the main tributaries discharging into the northwest-end of Hamilton Harbour. It carries about 14% of the natural water that flows into Hamilton Harbour. Wetlands at the Creek’s mouth are an important fish and bird habitat in an otherwise threatened area of Lake Ontario. They are of historic importance to whitefish, lake herring, and the endangered American eel. Grindstone Creek is prized for trout fishing.
Similarly, the headwaters of Bronte Creek and many of its tributaries contain a significant number of wetland areas that hold large quantities of rainwater which is slowly released to the creeks throughout the year. This flow is supplemented by groundwater that contributes a significant flow of cold water, even in periods of drought. These water sources combine to create a stable cold water ecosystem capable of sustaining populations of trout. Bronte Creek has steelhead runs in the spring and fall, smallmouth bass in the summer. Native brook trout and migratory rainbow trout can also be found in tributaries of Bronte Creek. Historically, it was an important habitat for Atlantic salmon.
There are two main tributaries located on the expansion site, the East and West Arm of the Mount Nemo Tributary. These tributaries provide flow contribution to the downstream fisheries of the Grindstone Creek. Part of its flow comes from the intermittently pumped discharge from the existing quarry. The West Arm provides fish habitat for a number of species, including the brook stickleback and pumpkinseed sunfish.
The East Arm of the west branch of the Mount Nemo Tributary originates as a headwater creek in the forested lands on the eastern half of the Nelson property. This branch connects the wetlands in the provincially significant wetland complex. It leaves the property through the wetlands in the forest near the southern boundary, and contributes to downstream fish habitat by adding flows and energy to the creek system. Fish like the green sunfish have been found in ponds downstream of the Nelson property.
Brook trout are one of the fish species found in Bronte Creek. (Photo credit: Philthy54)
The American eel is an endangered species. (Photo by Uwe Kils)
Click to Learn More:
Protecting Escarpment Rural Land (PERL)