History of Cootes Paradise Marsh
Tuesday July 26 2011
Prior to the 20th century, the nutrient-rich, shallow waters of Cootes Paradise thrived as a coastal freshwater marsh habitat. Almost 100 percent of Cootes Paradise was covered with emergent aquatic plants like wild rice and submergent plants like wild celery, providing food, shelter and migration stop-overs for a variety of birds, mammals, reptiles, amphibians and insects. The lush wetland also provided ideal spawning, nursery and adult habitat for many fish like bass, perch, pike, herring and trout. This lead to its protection, first as a fish sanctuary in the 1870’s, and then as a wildlife preserve in 1927, and finally through the formation of the Royal Botanical Gardens in the 1930’s.
The plentiful flora and fauna of Great Lakes coastal freshwater marshes did not go unnoticed by settlers in the 1800s. Cootes Paradise and its surrounding natural habitats offered abundant fishing and hunting opportunities, fertile farmland and convenient access to water. However, human settlement of Hamilton Harbour and its surrounding natural lands brought with it several stressors that, over time, had a cumulative impact on the natural abundance of Cootes Paradise and neighbouring lower Grindstone Creek marshes. Throughout Cootes Paradise’s watersheds, agricultural practices and residential, commercial and industrial development contaminated connecting creeks with sewage effluent, eroded soil and sediment and chemical runoff and destabilized flow patterns. In 1852 the Desjardins Canal, a shipping channel dissecting the marsh was recut through the centre of Burlington Heights directly connecting the marsh to the lake water levels, and disconnecting it from the Grindstone Creek marshes. In 1957 the lake water level became regulated with the construction of the St. Lawrence Seaway further disrupting natural water cycles in the marsh.
Introduced European and Asian species thrived in this altered environment. Among the first non native species (1870’s) the common carp was purposely introduced as a replacement for the disappearing salmon. The feeding and spawning behaviours of non-native carp uprooted and destroyed marsh plants and re-suspended sediment muddying the waters. By the end of the 19th century, in addition to the rapidly rising carp population, exotic plant species like purple loosestrife and reed manna grass, also purposely introduced to North America, began successfully outcompeting and eradicating, native plants in the wet meadow areas.
As human pressures on the watersheds increased, the decline in the health and biodiversity of Cootes Paradise became markedly visible. By the 1930s Cootes Paradise experienced a 15% permanent reduction in marsh vegetation, and by 1985 the level of plant loss reached 85% of its original coverage. This permanent loss of aquatic flora had a direct negative impact on water quality and the fish and wildlife inhabitants and economies of Lake Ontario. Since its dramatic decline began the Garden’s has been focused on restoring Cootes Paradise, with carp removal first attempted in the 1950’s.
Concerns over environmental degradation led the International Joint Commission to designate Hamilton Harbour as one of 42 Areas of Concern in the Great Lakes. In 1986, the Hamilton Harbour Remedial Action Plan was initiated to address this environmental degradation in the Harbour and key remaining areas like Cootes Paradise and lower Grindstone Creek. Under this plan, a variety of new conservation projects and monitoring programs have been implemented by a variety of stakeholders to control pollution, restore and improve fish and wildlife habitat and communicate the health status of the wetlands.
The nutrient levels (phosphorus and nitrogen) in the wetlands reflect the waters that flow into them. While the very high nutrient levels are improving, they are still extreme (hypereutrophic), resulting in ongoing algae blooms. Water sources include several urban storm drains and sewer overflows, a wastewater treatment plant (King St, Dundas) and 25 creeks draining just over 400km2 of land. None of these sources meet Provincial Water Quality Guidelines (PWQG) for Aquatic Life on a consistent basis. However, the largest creek, Spencer Creek, is the healthiest, originating 25km to the north above Beverly Swamp, and entering the western end of Cootes Paradise, with 95% of its watershed within the provincial Greenbelt.
The waste water plant located at the western tip of Cootes Paradise has undergone numerous upgrades over the past 40 years. Currently it flows at approximately 200 litres/second and operates as tertiary treatment plant (1985), with an overflow tank to stabilize and optimize its treatment ability (2005). The plant removes essentially all particulate, >95% of the phosphorus, but releases very high levels of nitrate (>15mg/l). Despite the significant phosphorus removal, the levels are still 7 times those found in natural waters, and are only exceeded by urban runoff as a source of phosphorus to the marsh, generating thick rafts of algae in the area it discharges.
While rural areas continue to improve practices to retain agricultural fertilizers on the land, the urban areas continue to expand. The rain water runoff from urban areas is surprisingly high in nutrients, and after rains provides concentrations poorer than that of the waste water treatment plant effluent. Due to the size of the urban areas in Ancaster, Hamilton, Dundas and Waterdown, this stormwater often overwhelms the marshlands, particularly after summer thunderstorms. Considerable improvements to inflowing water from the older portions of the City of Hamilton have been made through the construction of multiple sewer overflow tanks. This includes two on Chedoke Creek, one on Ancaster Creek, and one at the head of Westdale Creek. These now capture over 1 billion litres of water per year, diverting these waters to the main waste water treatment plant, and reducing sewer overflows by 95%.
Sediment contamination with nutrients has resulted from the above issues. Sediment samples have been taken on an ongoing basis since the 1970’s. These initial samples showed nutrient levels averaging 5 times that of natural sediments. However with ongoing improvements to inflowing waters the nutrients levels have healed significantly, and as of 2006 averaged only 50% higher than natural levels.
THE RBG FISHWAY
Located at the mouth of the Desjardins Canal—the only channel that connects Cootes Paradise and Hamilton Harbour—the Fishway is the Great Lakes’ first two-way fishway and carp barrier, and is one of the most visible indicators of the progress of Project Paradise.
The Fishway began operating in 1997. It is designed to keep non-native carp out of Cootes while maintaining the flow of water and populations of native aquatic species.
Before the installation of the Fishway, Cootes Paradise had an estimated carp population of about 70,000 adults. During the Fishway’s first year of operation, 95% of carp were excluded from the marsh, and since then this number has continued to drop, with monitoring in 2003 finding less than 1,000 adult carp in the marsh.
Eliminating carp from Cootes Paradise is considered a vital first step in the marsh restoration process.
Readers of pics4twitts send images and I enjoy publishing, below is an american goldfinch
Doug Worrall Photographer