Algae
During the summer of 2008, the state of Indiana monitored Geist, Morse and Eagle Creek Reservoirs for blue-green algae and the potential toxins it may produce. Their findings are posted online at a special site, www.algae.in.gov. There are currently no guidelines in the U.S. regarding the removal or reduction of these compounds from drinking water. They are on the EPA's watch list of "unregulated contaminants," essentially meaning that regulators are monitoring the presence, location and frequency of their reported occurrence, but do not have any treatment recommendations or standards of removal for these toxins at this time.
Many kinds of algae are present in most open waterways and streams throughout the state, and the summer of 2007 was ideal for them, due to the higher temperatures, warmer waters, cloudless days and lack of rainfall - all of which contribute to the conditions which encourage algae growth and reproduction. These algae are a natural part of the biodiversity which contributes to the biological food chain. Some of these algae have the capacity to produce algal toxins which may, at certain concentrations, cause some health concerns to those who come into contact with the water. Recreational water users are advised to rinse off after contact with potentially impacted waters, which may be in a lake, reservoir or stream.
While some of these algae may pose a risk for recreational users, standard drinking water procedures successfully remove the algae from drinking water.
Algae in Drinking Water Supplies
Past sampling data has indicated the presence of some forms of blue-green algae during various times of the year in the reservoirs which supply raw water to the Indianapolis Water treatment facilities. The presence of the algae does NOT mean algal toxins are also present, and there appears to be no correlation between the amount of algae present and whether or not the toxins are detected. Large amounts of blue-green algae may not produce any detectable toxins, or small amounts of the algae may or may not produce the toxins. Global research is currently underway in various locations to try to better understand how, when and why these toxins may be produced, and Veolia Water is actively involved in sharing data related with its many world-wide operations.
Conventional water treatment methods have been proven effective in removing both blue-green algae and the types of potential toxins which have been reported and found in Indiana waters. Powder-activated carbon and chlorine disinfection are commonly used to eliminate many unwanted contaminants. Although algal toxins are not currently regulated by the U.S. EPA, research has shown that small concentrations of the algal toxins microcystin and cylindrospermopsin such as those which have been reported can be effectively processed to meet World Health Organization standards.
The World Health Organization, which provided global advice on many issues, has posted standards for the algal toxins based on their data and information. These levels, which are not regulated in the U.S. by the EPA, advise that finished drinking water should contain no more of the toxins than 1 to 1.5 parts per billion (the equivalent of roughly one drop of water in an Olympic-sized swimming pool, or one second in a period of 31.7 years).
Eagle Creek Reservoir
Historically, Indianapolis Water has been challenged by taste and odor issues as a result of the presence of certain types of algae. Previously, the utility received more than 500 taste and odor complaints each year. Today, the number of complaints is less than 10 per year, due to changes in treatment practices and focused research and development.
Indianapolis Water has been challenged for the past several seasons with pseudanabaena algae in the Eagle Creek Reservoir. This algae produces a chemical, MIB (2-methylisoborneol), that some humans are very sensitive to. This is not a new phenomenon, as it typically takes place for one to two years after a drought year.
Eagle Creek Reservoir is especially susceptible to algae problems because it is relatively shallow and typically has limited movement of water through the reservoir. Increased sunlight penetration in recent years has contributed to algae blooms. Unfortunately it tends to grow very quickly during some conditions.
Indianapolis Water has successfully treated the reservoir with cutrine plus an algaecide that is safe for aquatic life and for humans.
We have also undertaken a significant collection of research activities where we are exploring a variety of measures to predict and control the growth of the algae, reduce the chemicals it produces, and share the information with other utilities around the world who have had similar challenges. Research and support provided by a new partnership with Indiana University Purdue University at Indianapolis Center for Earth and Environmental Science will help to provide short and long term solutions to future water quality challenges.
