Identifying Water Pollution by Sight and Smell
Is your stream a funky color?

To truly assess water quality, you have to look at water chemistry. However, water chemistry typically involves the use of meters, test kits and training that you may not have time or interest in. If that’s a little more involved than your life permits, the appearance of water can tell us a couple things about water quality.

What Color and Odor Can Tell You
Color and odor may give you a solid lead on what’s in water and may help you determine when to do further chemical testing.

While we hope you don't come across the following examples, they can be helpful indicators of what may be in your water. However, chemical tests are still needed to confirm the result of any visual interpretation.

The Rainbow Sheen
You could see a rainbow sheen on the top of the water like this. This sheen could result from iron-oxidizing bacteria or oil discharges. To differentiate, trail a stick through the film. If film readily breaks into small clusters, it is likely bacteria. If it swirls together, it is most likely an oil-based discharge from runoff.

photo source:

Signs of Sewage Overflows
If water appears gray and has a strong sewer odor, like the next picture, it could indicate a possible sewage overflow. Many sewer lines are constructed next to streams to take advantage of the continuous, gradual slopes of stream valleys. Blockages, inadequate carrying capacity, leaking pipes and power outages at pumping stations often lead to sewage overflows into nearby streams.

title photo source: Nine Mile Run Watershed Association

White Water
While both pictures below are white, the two pictures indicate very different things. The top picture has a sudsy appearance usually associated with detergents, such as residential or commercial car washing. The bottom one does not have suds and is most likely due to runoff from an abandoned mine aluminum discharge.

title photo source:

Abandoned mine drainage can also make the water appear orange from oxidizing iron or blue due to aluminum.

title photo source: Fayette Conservation District
title photo source: KDKA

Natural Discoloration
Stream water can also become naturally discolored as well. This can result from iron oxidation as in the top left picture, pollen on stagnant water in the early spring or summer as in the top right picture, an algal bloom as in the bottom left picture or tannins from fallen leaves as in the lower right.

title iron oxidation | photo source:
title pollen | photo source

title algal bloom |
title fallen leaves |

If you would like to be involved in more formal stream sampling of any kind, look up your local watershed group. Allegheny County has 11 active groups, and these groups may already have testing sites that you can help with. If there isn’t a watershed group in your area, feel free to contact ACCD or other local conservation districts to assist you with either starting your own group or connecting you with a neighboring group.

Find a Group