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• Lindi Osborne, Waterkeeper Swim Guide
  July 27, 2021

There are more than a few ways to describe the water that we swim in: cool, blue, refreshing, clean, vast, sparkling… But what if we look a little deeper into the characteristics of water. What can things like a water’s pH, salinity, and oxygen levels tell us?

Measuring the different properties of water can tell if something is wrong with the water or if something is changing over time. Keeping tabs on these characteristics can also at times provide information about how “swimmable” water is for both recreational water users and the aquatic life that depends on it to survive.

Here are 8 characteristics of water and what they can tell us about our a waterbody

1. pH

pH is a measure of how acidic or basic (alkaline) the water is. It can range from 1 (acidic) to 14 (basic/alkaline). Natural waterbodies usually range from 6 to 7. Waters with a higher or lower pH may be harmful to animals as well as humans, with pH levels above 11 potentially leading to skin and eye irritation.

2. Alkalinity

Alkalinity is the measure of how well water can withstand the addition of acids without dramatically changing its pH. The higher the water’s alkalinity, the better it is at buffering inputs of acidic pollution. When the pH of the water becomes too acidic, it severely impacts the fish, aquatic bugs, and other parts of the ecosystem.

3. Hardness

Hardness is a measure of how much dissolved salt, specifically, calcium and magnesium, is in the water. Water hardness is related to the alkalinity as harder waters will result in higher alkalinity. Water with too high a hardness makes poor drinking water and can harm aquatic life.

4. Conductivity

Conductivity is a measure of how well electricity can pass through the water. Conductivity is determined by how much salt is dissolved in the water, with higher levels of dissolved salt resulting in a higher conductivity reading.

Conductivity values differ between different waterbodies, and they can be used to detect pollution. In an unpolluted waterbody, conductivity values remain consistent, but in a polluted waterbody they may change dramatically.

5. Dissolved oxygen

Dissolved oxygen is a measure of how much oxygen is in the water. Fish and other aquatic animals need oxygenated water to breathe, so too little oxygen can be deadly. Low oxygen can also cause harmful algae blooms that hurt wildlife, people, and pets.

6. Salinity

Salinity is the concentration of salt in a saltwater waterbody. Salt in a waterbody is essential for the survival of plant and animal species, however salinity levels that are too high can be damaging to sensitive aquatic species and ecosystems.

Did you know: In Ontario, some freshwater creeks have gotten so salty that saltwater species have been found in them. For example, saltwater blue crabs are living in Mimico Creek in the Greater Toronto Area.

7. Turbidity

Turbidity is a measure of how clear or murky water is. Substances like clay, silt, algae, or plankton may cause turbid water. Turbid (murky) water is not necessarily harmful, and sometimes it only affects the aesthetic qualities of waterbodies. However, too much sediment or algae can harm humans and aquatic ecosystems. Pollutants can attach to the particles that are making the water look cloudy, so turbidity is sometimes (but not always) an indicator of water quality.

8. Temperature

Temperature is simply how warm or cool a waterbody is. Temperature impacts all of the other characteristics of water, and outlier temperatures can indicate an issue. When water is too warm, it’s referred to as thermal pollution.

Warming waters and climate change also lead to water quality issues that can make recreation unsafe. Our rivers, lakes, and oceans should be able to offer us refuge from blistering temperatures, but they cannot do so if we do not protect them.