Water Quality Parameter descriptions
The data set includes the measurements taken during our ongoing water quality monitoring program in
Cootes Paradise. Data have been collected by RBG staff since 1974; the information shown here dates from
1994 to 2004. Our full monitoring program includes data from seven different stations, of which we have
selected three.
Watershed – Cootes Paradise
Date/Year - The date on which the water sample was collected.
Site Name - The name of the site from which the water sample was collected. See map for
locations of the three sites selected for this data set (the centre of Cootes Paradise Marsh and
two major sources of water which enter the marsh, Spencer Creek and the tertiary treated effluent
of the Dundas Sewage Treatment Plant).
Station # - The numerical code for the sample site (see map).
Depth - The depth of the water in centimetres at the time of collection.
The Lake Ontario water cycle dramatically changes the depth of Cootes Paradise Marsh over the
season, with the typical annual cycle ranging about 70cm, reaching its high point in May or June,
and low point during November or December. The most extreme range occurred in 1998 when
the lake rose and fell 160cm. The depth in the centre of the marsh for an average water cycle
year changes from 60cm in May, to 50cm in July, and 5cm in November. During below average
years (such as 1999) water depths in May might only be 40cm, and in above average years (such
as 1998) they may be as much as 100cm. In 1935, the lowest recorded water cycle year, the
centre of Cootes Paradise remained dry for the entire year. Water level controls at the other end
of the lake don't allow this kind of extreme any more, though wetland plants are adapted to it.
Total Phosphorus - Phosphorus is the controlling element in freshwater ecosystems, limiting
plant growth, water clarity and dissolved oxygen. It is measured in mg/l, although often converted
to g/l.
Phosphorus is highly insoluble in water under normal conditions, and readily sticks to sediment.
As a result, high phosphorus readings are often associated with suspended sediment. Typical
Ontario water concentrations are between 2 and 25g/l. Concentrations above 50g/l generally
result in massive algae blooms which smothered aquatic life, use up the oxygen in the water and
cause murky water. The Ministry of Environment provincial water quality guideline is to maintain
levels below 30g/l.
Secchi depth - A measure of water clarity in centimeters.
A Secchi disc is a round, black and white metal disk, which is lowered into the water until it
disappears. The depth at which it is no longer visible is a measure of water clarity. The target for
Cootes Paradise Marsh is to always have water clarity greater than 150cm. Microscopic algae
(phytoplankton) and suspended sediment limit water clarity.
Dissolved Oxygen - A measure of the oxygen concentration in the water in mg/l.
Oxygen solubility varies with temperature, with clean water at 20C having an oxygen level of
about 9mg/l, while clean water at 5C would have and oxygen level of about 14mg/l. Oxygen
levels are also affected by plant respiration and decomposition. High plant densities can result in
supersaturation of oxygen on sunny days, but also lead to low oxygen levels at night and during
plant decomposition. Some forms of aquatic life begin to become stressed if oxygen levels drop
below 5mg/l, although most can tolerate 1.5 mg/l. The provincial water quality guideline is to
maintain concentrations above 5mg/l.
Total Ammonia - Ammonia is measured in mg/l and consists of unionized and ionized ammonia.
The relative proportion of these two types is dictated by oxygen, pH and temperature.
Unionized ammonia is an extremely toxic compound in aquatic ecosystems, with levels about
0.02 mg/l lethal to many forms of aquatic life. Unionized ammonia usually only occurs under low
oxygen and pH conditions. These conditions normally result from high organic (plant/animal)
decomposition rates, which are in turn caused by high phosphorus concentrations. Fertilizer spills
can also result in toxic ammonia levels. Decomposition to ammonia is part of the nitrogen cycle,
with the next breakdown step being nitrites.
Nitrite - Nitrites are measured in mg/l and are also highly toxic to aquatic life. As with ammonia,
high levels result from high organic (plant/animal) decomposition rates which are caused by high
phosphorus concentrations. Nitrites are a product of the bacterial breakdown of ammonia. They
are subsequently converted to nitrates by different bacteria. The provincial water quality guideline
for nitrites is concentrations below 0.6mg/l.
Nitrate - Nitrates are the least toxic of the nitrogen compounds and are measured in mg/l. Levels
above 2.5mg/l become toxic to eggs and larvae of many aquatic organisms. Natural clean waters
normally have levels below 1mg/l. Nitrates are taken up by plants for growth. Sewage treatment
plants generate extremely high nitrate levels.
pH - A measure of the acidity of the water on a scale from 1 (acidic) to 14 (basic). 7 is neutral.
Natural waters in Ontario range between 5 (acidic) and 9 (basic). In Cootes Paradise, pH levels
are generally neutral to slightly basic due to the high calcium levels found in the limestone of the
Niagara Escarpment. pH levels below 5 and above 10 are damaging to aquatic life and
dramatically alter the types and concentrations of other toxic compounds that can be dissolved in
the water. As an example, at pH levels below 6, mercury becomes soluble in water and thus
becomes part of the food chain. Along with acid rain, high organic decomposition rates can also
dramatically lower pH concentrations when the buffering capacity of limestone bedrock is not
available.
Total Suspended Sediment - A measure of the inorganic and organic material suspended in the
water column, measured in mg/l.
Suspended sediment affects the clarity of the water. The goal for Cootes Paradise Marsh and
provincial water quality guidelines are to maintain levels below 15mg/l in the natural environment.
Natural clean Ontario waters rarely exceed 5mg/l. The concentration of small clay particles in
local soils, combined with Cootes’ shallow depth and geographical orientation (its long axis aligns
with predominant local winds), results in bottom sediment that is easily resuspended on breezy
days. Wind storms, agricultural and urban runoff, resuspension of bottom sediment by animal
activity, and plankton levels are all contributors to high suspended sediment levels.
Inorganic Suspended Sediment - The level of clay, sand or mud suspended in the water
column and measured in mg/l.
Organic Suspended Sediment - The level of plankton and/or decomposing organic material
suspended in the water column and measured in mg/l. This value is primarily controlled by
phosphorus levels.
Chl A – Chlorophyll A is measure of phytoplankton (algae) in the water column, measured in ug/l.
The amount of algae in the water column is a reflection of phosphorus levels, water clarity and
water temperature. High concentrations of Chl A create murky water. The goal for Cootes
Paradise is to maintain levels at less than 25g/l.
Conductivity - a measure of the minerals dissoved in water, and measured in umhos/cm. Rain
water has very low conductivity (<100umhos/cm). while local spring (ground) water often has
conductivity level around 2500umhos/cm, a result of minerals dissolved in the water. No targets
exists for this parameter.
E coli - A measure of the population of Escherichia coli bacteria in the water column, measured
in number of bacteria/100ml of water. E.coli are intestinal bacteria, generally associated with
human/animal waste. The guideline for recreation activity around water is below 100
bacteria/100ml. Natural clean waters rarely have levels above 20 bacteria/100ml.
Stormwater - A recently adopted monitoring feature to separate water samples taken shortly
after a rain event which would be affected by urban/agricultural runoff.