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Physical conditions
The study area encompasses the floodplain of a medium sized creek, the valley slopes and some surrounding tableland. The East Lynde originates in the Oak Ridges Moraine about 11 km to the northwest. The upstream catchment area from the site is about 45 km2. East Lynde Creek flows southward, confluencing with the West Lynde just north of Highway 2 to form Lynde Creek which empties into Lake Ontario on the west side of Whitby. A water resource management strategy has been prepared for the entire Lynde Creek watershed (Gartner Lee Ltd. 1993).
The area is part of the South Slope physiographic region which is typified by gently rolling terrain with occasional drumlins, comprised of glacial till soils. Many streams possess steep sloped valley walls (Chapman and Putnam 1984) which is true of the site. Soils on site are of two types. Recent alluvial deposits in the bottomland along East Lynde Creek and Darlington Loam on the tablelands. Darlington Loam is a well drained fertile soil that may have a clay component, some stones, and it is slightly alkaline. Gully and sheet erosion is common (Olding et al. 1956).
The creek is a major influence on the site. The floodplain makes up most of the site. Figure 1 shows the regulated floodline and fill lines as defined by CLOCA. The floodplain is very well defined on most of the site with steep slopes rising up to 10 m above the floodplain on both sides.
The creek is in the mature stage which means that it is slow moving and forms distinct meanders on its floodplain. Over the course of decades, the creek may change its course, forming new meanders and abandoning old ones. Meander scars are apparent on the floodplain. The historic air photos from 1926 and 1946 clearly show that the creek has changed its course and in fact meanders more now than it used to. During the spring freshet or major storm events, the creek will overflow its banks onto the floodplain, depositing alluvial material and sometimes breaking up vegetation. It is during these events that most of the scouring takes place to the creek bed creating changes to the course. In 1999, the winter had less snow than usual and spring arrived earlier than normal. Consequently the freshet was not very pronounced this year.
Some groundwater seepage is present immediately along the creek banks and in the southeast corner of the site, but it is quite limited. The surrounding clay based till soils provide a poor recharge potential to the regional ground water system.
The lands south of Brooklin have a long history of agriculture. In the 1926 air photo, most of the study area comprising the East Lynde valley was open pastureland. The northernmost area along Winchester Road and the tableland area west of the creek were used to grow crops. A grove of mature deciduous trees shows up along the steep slope on the east side of the floodplain. Only a few scattered trees or shrubs are visible on the floodplain. The adjacent cedar woodlot just northwest of the study area had the same configuration in 1926 as at present. Land use in the 1946 air photo showed much the same pattern as in 1926. The valley was probably used as pasture until about 1970, and presumably cultivation of the tableland area ceased at about the same time.
The East Lynde Creek followed a more direct path with fewer and shorter meanders in 1926 or 1946 than it does presently. A short distance south of the study area was the site of an earthen dam and turbine operated grist mill known as Kent Mills. The mill was operated until about 1935 and was torn down about 1960 (J.M. Francis, pers. comm.). The mill pond is visible on the 1926 airphoto but had disappeared by 1946. The earthen dam is still apparent on the Francis property.
The recent housing boom in Brooklin has affected the East Lynde valley. A sanitary sewer was installed on the floodplain immediately east of the creek in the early 1990s. A storm water management pond was constructed about the same time to improve storm runoff from some of the residential developments. Another storm water pipe outfalls directly into the creek at the south west side of Brooklin Memorial Park.
We can expect further changes to the valley as Brooklin continues to develop. Highway 407 is proposed to cross East Lynde Creek on the south side of the study area. Additional urban residential developments are likely to occur in the future on both east and west sides of the valley.
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