Barrie Creeks, Lovers Creek, and Hewitt's Creek Subwatershed Plan

7.4 Urban interactions - land use, streams, and aquatic wildlife
When stormwater flows over urban areas, it is susceptible to picking up even more
contaminants than in other types of land use (Figure 7-8). In fact, the Barrie Creeks
subwatershed, which is the most heavily urbanized subwatershed in the Lake Simcoe
watershed, is also the largest per-hectare contributor of phosphorus to the Lake Simcoe
ecosystem (Figure 3-11).
As an area which is expecting significant growth and development, particularly in the Lovers and
Hewitt’s Creek subwatersheds, which have recently been annexed by the City of Barrie, many
of the stresses associated with urban land use may become more extensive (Figure 6-18),
including a projected increase in loading of phosphorus and chloride in watercourses, and an
increase in water temperature. In the near future, when most of this development is expected to
occur, these impacts may be more pronounced. Development sites are often stripped of
vegetation well in advance of development in an effort to reduce costs as the development is
built in phases. These bare soils are then subject to erosion by both wind and water.
As in agricultural landscapes, the contribution of sediment and phosphorus can have deleterious
impacts on species living in nearby streams by increasing water temperatures, decreasing
levels of dissolved oxygen, and disturbing spawning sites. Other contaminants that occur in
stormwater runoff from the urban parts of these subwatersheds however include phenolics,
metals, and organic compounds (Figure 7-8). At high levels, these contaminants can interfere
with enzyme activity in aquatic organisms, leading to changes in behaviour, movement, predator
avoidance, feeding rates, reproduction, reduced growth rates or even death.
Figure 7-8: Influences of urban land use on subwatershed health
Chapter 7: Integration and implementation 324