Almost 200 hundred years of human intervention on sections on Laurel Creek have left a main channel that no longer resembles or functions in its original form. The stream has been straightened or impounded for its entire length, save the headwaters where urbanization has not yet taken place (see attached map). These changes reflect a predominant planning practice which treated streams as fragments, isolated from the landscape. The resulting channel can be likened to a trough which can wisk away troublesome water, facilitating construction, and sewage and stormwater handling.
This generalized view of the streamÕs development over its urbanized history provides reasons for vegetation and soil disruptions along its course, as well as clues for future planning practices and restoration efforts. Not included in this study is the effect that these changes have had on the flow regime of the stream due to the possible disruption between groundwater and stream baseflow.
Anthropogenic alterations to the channel of Laurel Creek are reflected in vegetation changes to the riparian zone. Mapping the history of environmental change began with an investigation of severely disturbed forest remnants dominated by the invasive aliens European buckthorn (Rhamnus cathartica) and garlic mustard (Alliaria officinalis). Moving the stream channel disrupted the hydrological connections between the banks and the shore; this action dehydrated the soils and allowed for the invasion of typical native riparian flora by alien vegetation. However, some species of riparian vegetation persist, such as peach leaved willow (Salix amygdaloides) which marks the location of the original channel. Small wetland pockets created by surfacing groundwater which formerly fed stream baseflow is another indication of original channel location. Typical upland species such as sugar maple (Acer saccharum) and American beech (Fagus grandifolia) growing beside the engineered channel are further evidence of channel moving.
Alterations to channel morphology were next investigated for Laurel Creek on University lands, and then for the remaining stream from the University to its confluence with the Grand River. From the headwaters to the Grand River, very little natural channel remains. The channel has been altered for agricultural drainage, road building, sewer laying, for historic millponds and contemporary impoundments, for flood control and recreation.
Historical cartographic information was digitized and matched with contemporary creek location. Channel information was researched and gathered from a combination of airphotos (1930, 1945, 1946), historical maps of the University property and the City of Waterloo, written accounts of local development and personal communications with long time residents in the area. This information was georeferenced, and digitized to overlay current digital drainage files based on 1:10,000 Ontario Base Maps from the Ministry of Natural Resources. In some cases it was necessary to hand transfer the information before digitization was possible. Final confirmation of the changes identified was made by walking the length of the main channel. At this time it was possible to locate remnants of the original channel location which coincided with these sources.
The implications for stream restoration involve recognition of those natural stream processes which have been altered when the stream has been moved. Disruption of the hydrological connection between the banks and the stream suggests that riparian vegetation which relies on this hydrology will not be appropriate for restoring stream banks. Bank soils are not hydric organic soils, but composed of mineral soils deposited from the bottom of the artificial channel to the banks. However, possibilities for restoring meanders to former channels which continue to support riparian vegetation because of residual ground water should be investigated.
Copies of the following maps for the entire creek have been deposited in the University of Waterloo Map Library:
The maps are also available in digital form from Environmental Information Systems, Room 277E, Biology 1, University of Waterloo.
Related Publications (available in the Ecology Laboratory, ES2, University of Waterloo).
Hendrickson, C. 1966. A natural solution. University of Waterloo Magazine, Spring 1966, 16-19.
Hendrickson, C. 1966. Plants provide clues to changes in Laurel Creek. EcoNexus No.5, Spring 1996, 16-19.
Hendrickson, C. and J. Cox. 1995. Preliminary findings of the riparian ecology group regarding proposed changes to the section of Laurel Creek upstream of Silver Lake. Silver Lake Roundtable, July 1995.