Weird Water Events

Weird Water Events

by Erin Moran, Aquatic Specialist I
Brazos River Authority

If you live near or visit rivers and lakes in Texas often, you may have seen some baffling sites on the water and wondered what was going on. While industrial and wastewater spills sometimes happen and will require cleanup, most often the weird things you see on or in the water are naturally occurring.

The Brazos River Authority environmental staff has put together the following list of items you may see while visiting a river or reservoir in the Brazos River basin. If you think you may have encountered one of these strange phenomena, take a photo and send it to us at information@brazos.org.

Pollen Build Up

Pollen can build up on the water’s surface and create a film. It can be white, yellow, or green and will break apart when the surface of the water is broken. This is the same pollen that builds up on your car during the spring and summer.

Whiting Events

Sometimes calcium carbonate, a natural substance also found in eggshells and seashells, will leach out of the environment and cause a “whiting event” on the surface of a lake. These events usually occur in the summer. Changes in water temperature combined with an abundance of phytoplankton (microscopic plant-like organisms) allow small particles of calcium carbonate to form, which rise to the surface of the water and give it a light, chalky appearance.

Bacteria Film and Slime

Occasionally a film will develop on the water’s surface that may appear to be oil pollution; this is natural bacteria reacting to the presence of minerals within the water. Water carries minerals such as iron, manganese copper, and sulfur, and certain kinds of bacteria consume these minerals for energy. The bacteria will attach to the surface of the water and when the sunlight reflects off of them, it appears as an oily film or slime.

Iron Reducing Bacteria

Red, orange, and brown films on the water’s surface are the result of iron reducing bacteria. These naturally occurring bacteria get energy from consuming iron within the water column. The result of this energy-deriving process is ferric oxide, which does not dissolve in water. Ferric oxide rises to the surface and can appear as a colorful, gelatinous slime.

Periphyton Buildup and Algae Mats

Periphyton is a mixture of algae, bacteria, and microbes that grows on river and lake beds. Sometimes periphyton and/or algae will ‘bloom’ and grow abundantly, causing large quantities to build up on rocks and other hard substrates. This happens most often in the summer, when an abundance of nutrients and sunlight give the periphyton and algae enough energy to grow exponentially. The buildup can be so large that large pieces of the periphyton growth or the algal mats will slough off and float to the surface of the water. Algal growth can cause large strings of algae to float in the water, attached or unattached.


Duckweed is an aquatic plant which floats on the surface of slow-moving or still water. It is a small and simple plant; it is light green and the only obvious part of the plant is a leaf like structure that is a few millimeters wide. It sometimes grows in dense colonies that cover the surface of the water. Duckweed is transported easily by waterfowl and humans and can quickly grow in new areas. Although duckweed can sometimes be a nuisance, it provides shade and can reduce algae overgrowth and helps control the breeding of mosquitoes.


Bryozoans are immobile, filter-feeding aquatic invertebrates that are around 0.05 millimeters long. Sometimes colonies of bryozoans form and appear as a brownish-grey, jelly-like, spherical blob that can be free-floating or attached to an object within the water. They are generally a sign of good water quality.

Tea Colored Water—Golden Algae

Tea-colored water can be a sign of golden algae; the color is a result of the pigments within the organisms. Golden algae are a large group of algae that can be found in fresh water. Only one species of golden algae, Prymnesium parvum, produces toxins that are harmful to fish and other gill-breathing aquatic organisms.

“Tomato Soup” or “Chocolate Milk” Colored Water

“Tomato soup” or “chocolate milk” colored water happens due to suspended solids within the water. This can happen due to a disturbance in the stream bed that suspends particles that have settled to the bottom, or an event that bring in particles from outside the stream. Examples include any rainfall event or release of water from a dam. The color of the water can vary due to the natural pigments and compounds found in soil, which vary between geographical regions.


Foam is often the result of natural processes within a waterway. Organic material within the water is churned up and forms bubbles as a result of turbulence. Examples of foam-causing events include wind turbulence along the water and water releases from dams. Foam is usually persistent, light, and not slimy to the touch.

Dead Algae

Algae is a natural component of any waterway. It grows on rocks, plants, and other soft or hard substrates and is an important part of the aquatic community, oxygenating the water and providing a food source for aquatic organisms. Algal blooms can be natural, but can also be the result of a high amount of nutrients in the water. When an algal bloom occurs, mass quantities of algae can die and float to the surface of the water or get stuck on things within the water.

If you come upon a stretch of water in a river or reservoir in the Brazos River basin affected by one of these phenomena and are concerned about its origin, please snap a few photos and send them to the Brazos River Authority at information@brazos.org with information regarding the location as soon as possible. Our environmental and lake staff with attempt to determine the cause and origin of the issue and initiate cleanup if necessary.