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HOME / WATER / STREAMS, PONDS, WETLANDS, AND ESTUARIES / WATER QUALITY /


Red, Green, and Brown: What's in the Water?

Each year people see things in streams, ponds, and estuaries (together called surface water) that cause concern.  In most cases, this does not mean that the water is polluted. Often, there is a natural cause for these conditions.
 
Some of the more commonly noticed things include:
 
Oily Sheen
Yellow Scum/Slick


Of course not everything in the water is due to natural causes.  If you are concerned about water quality because of something you have seen, please contact the PEI Department of Communities, Land and Environment at 902-368-5044.  If you suspect that a problem may need immediate attention (such as a chemical or petroleum spill, or dead or dying fish or shellfish) please contact the Environmental Emergency number at 1-800-565-1633.


Foam
Foam can develop naturally in water. Decaying plants, leaves, and animals (organic matter) act much like soap.  The organic matter allows the water to mix with air. This creates bubbles and foam in areas where the water is moving quickly, such as below waterfalls, or where waves break on the shore.

Foam in slow moving area below a culvert 
Foam in slow moving area below a culvert          Foam on the shoreline

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Orange or Brown Slime 
Orange/brown slime is caused by harmless bacteria that form slimy or fluffy deposits. These deposits ‘rust’ when iron (in the bacteria) and oxygen (in the air) come together.  This slime is most commonly found near springs, where, iron-rich groundwater comes to the surface. Slimes can also form where there is an abundance of decaying plant or animal material.

Orange slime in an artesian spring Brown slime in a stream
Orange slime in an artesian spring                      Brown slime, with decaying algae, in a stream

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Green Coloured Water
Ponds and estuaries often turn green during the summer months.  The colour, which can range from drab olive to ‘lime ricky’ green, is the result of a heavy growth (or bloom) of very small (microscopic) algae (known as phytoplankton). Blooms are often the result of nutrients in water and as a result are a concern to the environment.
Olive-green algal bloom in a pond Lime-Ricky coloured algal bloom in a pond
Olive-green algal bloom in a pond                       Lime-Ricky coloured algal bloom in a pond

A very bright turquoise green or blue–green colour to the water may indicate a bloom of blue–green algae (cyanobacteria).  These blooms can also create a granular scum on the surface. If you suspect a blue–green algae bloom, please report it to the PEI Department of Communities, Land and Environment (368-5044). 

Blue-green algal bloom Blue-green algal bloom showing granular appearance
Blue-green algal bloom                                        Blue-green algal bloom showing granular appearance

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Green Moss or ‘Clouds’ 
Masses of filamentous algae (single algae cells that form long visible chains or filaments) can appear to form moss or clouds on the bottom of freshwater ponds.  These algae masses are often slimy to the touch.

Green filamentous algae on the bottom of a pond
Green filamentous algae on the bottom of a pond

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Mats or Green Scum
Mats or green scum are generally caused by a large growth (or bloom) of water plants or algae. Duckweed and filamentous algae are the most common causes in freshwater ponds.  Sea lettuce forms mats in many Island estuaries.

Duckweed Floating, filamentous algae
Duckweed                                                            Floating, filamentous algae

Sea lettuce mat
Sea lettuce mat

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Red, Brown, or Tea-coloured Water
Red, brown, or tea-coloured (but otherwise clear) water is due to the presence of organic matter or plant pigments called tannins. The tannins actually ‘stain’ the water.  Unlike the silt in muddy water, the tannin will not separate out if the water is left standing in a glass or bottle.

Tannins in water
Tannins in water

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Milky White or Cloudy Green Coloured Water
Milky white or cloudy green coloured water in an estuary (the area where fresh and salt water mix) is generally a sign that an ‘anoxic event’ has occurred.  These events happen when large amounts of algae or sea lettuce decompose.  Decomposing plant material uses all, or most, of the oxygen in the water. Anoxic events result in a cloudy white to grey or green discolouration of the water as well as a rotten egg or rotten turnip type smell.
 
 Milky appearance of an anoxic event Anoxic event with a cloudy grey-green appearance
Milky appearance of an anoxic event                     Anoxic event with a cloudy grey-green appearance

Please report anoxic events to the PEI Department of Communities, Land and Environment (368-5044). 
 
Click here to see a list of estuaries with reported anoxic events since 2002. 

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Oily Sheen
One common cause of an oily ‘sheen’ on the surface of water is the presence of harmless iron- or manganese-loving bacteria.  These bacteria are often found in waterlogged soils.  Decaying plant and animal material can also create an oily appearance. Oily sheens caused by natural causes have no petroleum odour. Sheens caused by petroleum will also flow back together again when disturbed by poking with a stick. Natural sheens will stay separated.

Oily sheen on the shoreline
Oily sheen on the shoreline


Yellow Scum/Slick
A pale yellow scum or slick is sometimes visible in Island waterways (including beaches) during the spring and early summer. Although it may look and behave like an oil slick, this scum is usually due to large amounts of tree pollen in the water. The pollen is slightly sticky, which makes it clump together. Because it is very light, it floats on the surface.  Sometimes the scum will cover a large surface area of water. Islanders may notice that their cars and the surface of puddles are also covered with pollen. 

A large amount of pine pollen mixed with beach 
wrack near St. Peter's Harbour, PEI (June 2013). 


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