Every stage of pits and quarries has impact on the natural environment. At site preparation, vegetation is removed, reducing natural habitat for a variety of animals and moving topsoil and subsoils into berms around the perimeter of the site. The disturbance of the soil can introduce invasive plants, encourage the growth of aggressive plants, stunt the growth of native plants and/or totally remove them. Pits and quarries represent loss of habitat and loss of connectivity to wildlife needing corridors.
During extraction, if not before, streambeds and wetlands may be altered. A drop in the water table means these habitats will change or cease to exist. While some wetlands are deemed regionally or provincially significant, the MNRF has not carried out evaluations of many. Some are being removed under Ministerial Zoning Orders. The steep faces of pits and quarries may provide habitat to some cliff-dwelling birds, e.g., swifts, but they are unsuited to others e.g., bobolinks and other grassland nesters. Where deep quarries leave stands of trees or streams high and dry, they invariably cease to exist shortly, leaving aquatic, amphibian or terrestrial species without habitat. Promises of restoration of habitat during interim uses that exceed the average lifespan of species do not serve to protect flora and fauna. Alternations in headwaters have consequences downstream to other habitats. Changes in temperatures, rate of flow or turbidity can harm various fish, crustacean, or benthic species.
Post-extraction, pits and quarries often remain dormant before rehabilitation occurs. Rewilding, though it seems preferable to the scarring of the landscape, does not restore the pre-aggregate habitat. There is some doubt among scientists that landscape features such as soils, wetlands and cold-water streams can be restored after “interim use” which can go on for decades.
Both the extraction period and post-extraction, the changed landscape can allow the infiltration of pollutants into ground water which will have impacts on seeps, springs. and other outflows as well as downstream communities of plant, animal and human species.