Saturday, September 18, 2010

Happy World Water Monitoring Day!

According to my handy-dandy, newly compiled Calendar of Science Holidays, today is World Water Monitoring Day. According to the World Water Monitoring Day website, the purpose of this day is to encourage people to identify their local water bodies (like rivers, lakes, streams, oceans) and take steps to protect them by conducting basic water monitoring.

The World Water Monitoring Day website tracks water quality monitoring data from around the world. Local groups upload their findings by geographic location. The basic water monitoring measures tracked for this website are pH, dissolved oxygen (DO), temperature, and turbidity. These measures are important for many reasons, but here's some information on how they affect aquatic life:

pH tells you if the water is acidic, basic (alkaline), or neutral. Water with high acidity or high alkalinity is not healthy for aquatic life. Natural waters should have a pH that is roughly neutral.

Dissolved oxygen tells you how much oxygen in the water is available to aquatic life. For example, if lake water has low dissolved oxygen, the fish won't be able to breathe. In general, water bodies that are in motion (streams, rivers) have higher dissolved oxygen than stagnant water bodies like lakes and ponds.

Temperature is a useful measure of a water body's resilience to atmospheric temperature changes. Let's say that one day, the temperature outside is 90 degrees F and the next day it drops down to 40 degrees (this can happen where I live!). If water temperature in lakes and streams followed those extremes, most - if not all - aquatic life would die. But water generally heats and cools more slowly than air, which allows lakes and streams to withstand daily atmospheric temperature fluctuations. When you monitor water temperature, you don't want to see rapid changes over short periods of time. If a polluter suddenly dumped a large volume of hot wastewater into a small stream, for example, you would see a big temperature difference from one day to the next and you might see lots of dead fish floating on top of the water.

Turbidity looks at the amount of suspended material in the water. Very turbid water can look green from high concentrations of algae or brown from suspended sediments. Often, pollution increases turbidity. Crystal clear water, however, doesn't guarantee that a water body is healthy. Sometimes, it means that the water is "dead" and that no aquatic life is living there. Fish need algae and other suspended materials for food.

A Secchi disk is used to measure the turbidity of your water. You basically drop it down into a water body until you can't see it any more and measure at what depth that occurs.
Photo credit: Secchi Dip-In | Biological Sciences Department Kent State University

To learn more about these four water quality measures, check out this page of World Water Monitoring Day handouts or visit EPA's Volunteer Monitoring Program. In the US, you can find local monitoring clubs at EPA's Surf Your Watershed. Check with environmental groups in your area to see if they offer water quality monitoring classes. Getting to know your watershed is a great way to get acquainted with your local environment.

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