What’s with the foam?

What’s with the foam?

Many people enjoy a good bubble bath, but a foam-like substance on top of the Brazos River may not be as attractive.

Recent visitors to parts of the Brazos River have noted a foamy appearance to parts of our waterways. And surprising to some, the phenomenon of foam is most often the result of natural processes.

“The source of the foam is most likely a combination of the turbulent water caused by recent storms, upstream water releases, and a build-up of dissolved carbon and phosphate in lake and river sediment, and new inputs from the recent storm events,” said Tiffany Malzahn, Brazos River Authority environmental and compliance manager. “When the water release is ceased, and flow returns to normal, the foam should dissipate.”

Natural foam may smell fishy or earthy. Sometimes its color is white, off-white, yellowish or brownish.

Natural foam is technically caused by dissolved organic carbon and orthophosphate phosphorus, Malzahn said. The primary source of those two components in reservoirs and streams is from runoff from surrounding watersheds and internal loadings, she said.

“Watersheds deliver large amounts of organic matter, sediment and nutrients to streams and lakes during storm events, via stormwater runoff,” she said. “Additionally, when leaves, twigs or other organic substances fall into the water and begin decaying, they release compounds such as dissolved organic carbon and orthophosphate phosphorus, which are natural surfactants, or substances which tend to reduce the surface tension of a liquid in which it is dissolved.”

Water molecules are normally attracted to each other as with most liquids.  This attraction creates tension at the surface of the water, which allows some insects to glide across it.  Surfactants break the surface tension, which in turn allows air to more easily mix with water and creates bubbles, Malzahn said.

Foam is produced as air is churned into water by turbulent flow or wave action. Additionally, clay and fine soils that tend to float near the water’s surface contribute to foam production.

Natural foam is of no threat to human health. While industrial and wastewater spills sometimes happen and require cleanup, most often the weird things on or in the water are naturally occurring.


In fact, some studies indicate foam can be beneficial to fish as a natural cover or a place to hide, she said. However, aesthetically, it’s not appealing when it accumulates on the banks.

So is all foam good?

It’s never as easy as that. Some foam in water can indicate pollution. When deciding if the foam is natural or caused by pollution, consider the following:

  • Wind direction or turbulence: Natural foam occurrences on the shoreline coincide with the onshore winds. Often, windrows of foam can be found along a shoreline and streaks of foam may form on open waters during windy days.
  • Natural occurrences in rivers can be found downstream of a turbulent site.
  • Texas Commission on Environmental Quality Region 9 and the city of Waco staff have said this is a regular occurrence below Lake Waco when the U.S. Army Corps of Engineers makes large releases.
  • TCEQ staff members from other regions have stated observing the same phenomena at lakes around the state.
  • The presence of silt in water, such as from a construction site or runoff during a storm event, can cause foam.
  • Presence of decomposing plants or organic material in the water.
  • Feeling: Natural foam is usually persistent and light, not slimy to the touch.

Additionally, both algae and plankton can release chemicals that cause foaming into the water, Malzahn said. However, they usually do not release enough chemicals to create a build-up. There is no evidence at this time that connects foam accumulation to golden algae.

Natural foam is somewhat ephemeral, meaning it can last for a few days or even a week, but will come and go. If there is an industrial pollution source, the foam is usually more persistent or the foam development will follow some sort of pattern, such as occurring immediately after discharge.

The BRA environmental team regularly tests water samples from across the Brazos River basin. The BRA has participated in the Texas Clean River Program for more than 20 years, by collecting water quality data from sites in reservoirs, creeks and streams across the river basin. The teams monitor roughly 100 sites and send and share that data with the Texas Commission on Environmental Quality.

The Brazos River Authority works with state and federal authorities to monitor the quality of Brazos River basin surface water while providing clean, potable drinking water as well as wastewater services to the people of the Brazos basin.

If you come upon a stretch of water in a river or reservoir in the Brazos River basin and are concerned, please snap a few photos and send them to the Brazos River Authority at information@brazos.org with information regarding the location.