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

The Barrie Creeks, Lovers Creek and Hewitt’s Creek Subwatershed Plan
Where 90% of samples at Hewitt’s Creek and 70% of samples at Lovers Creek meet long term
exposure chloride guidelines, only 7% of the samples collected at Hotchkiss Creek meet the
objective (Table 3-4). The CWQG also use a short term, or acute, exposure guideline of 586
mg/L which estimates the point at which severe effects to the aquatic ecosystem are likely to
occur over a 24 to 96 hour exposure period (Table 3-1). From 2008 to 2010, nine samples
(10%) exceeded this guideline at Hotchkiss Creek while no exceedances occurred at Lovers
Creek or Hewitt’s Creek.
Table 3-4: Surface water quality comparison for Lovers, Hewitt’s, and Hotchkiss Creeks (2008-
2010).
Monitoring Station
Current Conditions (2008-2010).
Percentage of samples that meet objectives
Orange = median concentration > objective
Green = median concentration < objective
Chloride
Phosphorus
Nitrate
TSS
Hewitt’s Creek 90 55 82 89
Hotchkiss Creek 7 59 99 86
Lovers Creek 70 60 100 87
Objective 128 mg/L 0.03 mg/L 2.9 mg/L 30 mg/L
3.2.3.1. Phosphorus
As the historic concentrations at Lovers Creek are
unusually low compared to just about everywhere else in
the watershed, it is one of the few tributaries showing an
increasing trend in phosphorus concentrations when
examining the entire period of record. While this is a
concern, it is important to realize that while more rapid
development in the subwatershed is likely causing this
increase, the total phosphorus load from the Lovers
Creek subwatershed only makes up 1.4% of the total
load going into Lake Simcoe each year (discussed
further in the Stressors section of this chapter). For
comparison, the Beaver River, which today has relatively
low concentrations and shows a declining trend, had
much higher concentrations through the 1970s and
1980s, the majority of which exceeded the guideline
(Figure 3-2).
Reading & Interpreting Box Plots
A box plot presents a data set in
graphical form. The shaded portion
of the box represents the middle
50% of the data set showing where
the majority of the values fall and
the spread of the data. The line in
the box is the median (50 th
percentile) of the data set. The
whiskers show the lower and upper
quartiles of the data set. The points
above and below the whiskers
represent outliers in the data set at
the 5th and 95th percentile. A red
line has also been included to
highlight the applicable guideline
for the parameter.
Chapter 3: Water Quality – Surface and Groundwater 85