Duffins Creek & Carruthers Creek Watersheds Features
While Duffins Creek watershed has experienced urban growth in recent years, only 10% of the lands are urban and 19% are urbanizing. 71% of the watershed still has a predominately rural landscape.
In both Duffins Creek watershed and Carruthers Creek watershed, rural areas dominate the north, and the southern portions are urban or urbanizing. Farming activity includes livestock, crops, and orchards. Many estate subdivisions and rural non-farm residences are also in the rural area.
Duffins Creek watershed has three physiographic units: Oak Ridges Moraine, South slope, and the Lake Iroquois plain.
Carruthers Creek watershed physiography includes the South slope, and the Lake Iroquois plain.
The Oak Ridges Moraine is an upland area, the source of many streams like Duffins Creek which drain into Lake Ontario to the south. The Moraine's hilly terrain is composed mainly of sand and gravel, with scattered small ponds.
The South Slope of the Oak Ridges Moraine has many drumlins, which are long and narrow mounds pointing upslope formed from glacial debris. Fast-flowing streams in this area carved sharp valleys through the glacial till, an accumulation of unsorted, unstratified mixtures of clay, silt, sand, gravel and boulders. Many types of soil are found along the South slope, some of which are good for agriculture.
Rolling hills of the Oak Ridges Moraine
Along the shoreline of ancient Lake Iroquois, coarse soil particles like sand and gravel settled during glacial retreat, leaving a band of sandy soils. To the south, the Lake Iroquois plain is composed mainly of clay, and gently slopes towards the shore of Lake Ontario.
Historically, both watersheds were dominated by vast forests which had tremendous influence on the hydrology of the watershed. With European settlement came deforestation and a variety of agricultural practices which negatively impacted the system. Other changes due to urbanization, such as transportation corridors, groundwater extraction, in-stream barriers, and ponds, have negatively impacted the watersheds.
Fortunately, the impacts to these watersheds is currently limited due to the low percentage of urban development. For now, the negative impacts to aquatic habitat and species have not been substantial.
The high percentage of rural land in Duffins Creek watershed means that 40% of the watershed has natural cover, of which 25% is forest, 11% is meadow, 3% is successional, and 2% is wetland.
Carruthers Creek watershed is roughly 83% rural, mainly farm land. Only 3.7% of the watershed is natural cover, far below the recommended 30% minimum considered necessary for a healthy watershed. However, since only 13% of the watershed is urbanized, there is great potential to restore selected areas of natural cover for a more balanced mix of natural and agricultural land. Currently, the lack of natural cover has resulted in degraded habitats and lack of opportunity for migratory species, especially birds, to find safe passage through the watershed.
Duffins Creek's 81 kilometres of streams are in relatively good condition and are dominated by coldwater aquatic communities such as sculpin, trout, and numerous other fish species.
Carruthers Creek is a small watershed containing only 61 kilometres of streams. Riverine habitat is by far the most common type of habitat and can be divided into coldwater and warmwater habitat categories. The middle and upper reaches of Carruthers Creek are coldwater habitat with temperature-sensitive species such as rainbow trout and mottled sculpin. Lower reaches of the creek below Bayly Street are warmwater habitat due to the very low gradient, distance from groundwater sources, close proximity to Lake Ontario. Young-of-the-year northern pike are found in the warmwater reaches.
Over the past 50 years, conditions in some areas of the watersheds has improved. For example, in some headwater areas of Duffins Creek where the glacial soils are poor for agriculture, and in the provincial Seaton and federal airport lands, there has been significant regeneration of table land and riparian forests. This has increased forest cover led to a reduction in surface flows and stabilization of the overall flow regime. The result is better aquatic habitat and an overall improvement in the condition of some fish communities.
In the 1950s, during the first extensive fish survey of the Duffins Creek watershed, sensitive species such as brook trout and sculpin were largely restricted to the headwater areas. Since the 1950s the conditions have improved and these species have extended their range to other areas. Many areas still require an increase in woody riparian vegetation to provide habitat for coldwater species. There is still room for improvement to the aquatic system.