Kansas Water Science Center
Cyanobacterial (Blue-Green Algal) Blooms:
|Cyanobacteria may produce taste-and-odor compounds that cause malodorous or unpalatable drinking water. Cheney Reservoir, Kansas. June 2003. Photo Courtesy of KDHE.|
Freshwater and marine harmful algal blooms (HABs) can occur anytime water use is impaired due to excessive accumulations of algae. In freshwater, the majority of HABs are caused by cyanobacteria (also called blue-green algae). Cyanobacteria cause a multitude of water-quality concerns, including the potential to produce taste-and-odor causing compounds and toxins that are potent enough to poison animals and humans. Taste-and-odor compounds and toxins are of particular concern in lakes, reservoirs, and rivers that are used for either drinking water supplies or full body contact recreation. Taste-and-odor compounds cause malodorous or unpalatable drinking water and fish, resulting in increased treatment costs and loss of aquacultural and recreational revenue. Cyanobacterial toxins (cyanotoxins) have been implicated in human and animal illness and death in over fifty countries worldwide, including at least 35 U.S. States. Human toxicoses associated with cyanotoxins have most commonly occurred after exposure through drinking water or recreational activities.
"Taste-and-odor producing cyanobacteria Cyanobacteria may also produce toxins that are potent enough to poison humans and animals such as cattle and dogs. Mozingo Lake, Missouri. October 2001. Photo by J. L. Graham.
The cyanobacterial compounds most commonly associated with taste-and-odor episodes are geosmin and 2-methylisoborneol (MIB). Cyanobacteria also produce a chemically and bioactively diverse group of toxins, all targeting fundamental cellular processes and thereby affecting a wide range of organisms. Cyanotoxins implicated in human illness include microcystin, cylindrospermopsin, anatoxin, saxitoxin, and β-methylamino alanine (BMAA) Kansas Department of Health and Environment. Because of potential human health risks, cyanotoxins are currently on the U.S. Environmental Protection Agency drinking water contaminant candidate list (CCL).
|Cyanobacteria may form thick accumulations in near-shore areas. Binder Lake, Iowa. August 2006. Photo by J. L. Graham|
Although anecdotal reports are common, few studies have documented the distribution, occurrence, and concentration of taste-and-odor compounds and toxins in cyanobacterial blooms throughout the United States. In addition, while the general factors influencing cyanobacterial bloom formation are well known the specific factors driving particular occurrences of taste-and-odor compounds and toxins remain unclear. Taste-and-odor compounds and cyanotoxins represent both economic and public-health concerns and resource managers, drinking water treatment plant operators, lake associations, and local officials are increasingly faced with decisions about cyanobacteria that affect public awareness, exposure, and health. Understanding the environmental factors associated with the occurrence and concentration of taste-and-odor compounds and cyanotoxins is key to lake management and drinking water treatment decisions and minimization of human health risks.
"Taste-and-odor producing cyanobacteria bloom in Cheney Reservoir, south-central Kansas. Cheney Reservoir, Kansas. June 2003. Photo Courtesy of KDHE.
Severe taste-and-odor episodes in Cheney Reservoir, a key drinking water supply for the city of Wichita, Kansas, during the early 1990’s prompted water-quality studies to identify and mitigate potential causes. Recent USGS studies have focused on real-time estimation of water-quality constituent concentrations and transport from the watershed and the description of in-reservoir conditions that may result in cyanobacterial production of taste-and-odor compounds. The taste-and-odor compound geosmin, probably produced by the cyanobacterial genera Anabaena, is the likely cause of taste-and-odor episodes in Cheney Reservoir. Continuously monitored variables, such as light, temperature, conductivity, and turbidity have been used to successfully predict when geosmin concentrations will exceed the human detection limit of 10 nanograms per liter (view real-time estimates of geosmin concentrations in Cheney Reservoir). Ongoing studies at Cheney Reservoir will link biological, physicochemical, hydrological, and meteorological processes to refine relations to estimate taste-and-odor occurrences and develop new relations with other variables of concern, such as cyanotoxins. The city of Wichita plans to use these models, along with other variables measured in real time, to aid the management of the resource and decrease water-treatment costs.
The Kansas River drains about 60,000 square miles in Colorado, Nebraska, and Kansas. The downstream part of the drainage basin in northern Kansas supports a growing population of more than 700,000 people and a wide range of urban and agricultural activities. Along the Kansas River between Wamego and Kansas City, Kansas, there are 16 permitted wastewater discharging sites (see map) with 22 others located on tributary streams. Rapid population growth and urban development are a particular concern along the Kansas River between Topeka and Kansas City. High concentrations of ammonia and bacteria have been detected in this reach of the Kansas River because of the close proximity of communities that discharge to the river and the additive effect of their wastewater treatment facilities. There are also several proposed wastewater treatment facilities that will discharge to the Kansas River. Before these proposed facilities can be allowed to discharge into the Kansas River, the assimilation capacity for ammonia and bacteria decay rates in the river need to be determined so that water-quality standards are not exceeded.
Lake Olathe is an important recreational resource for the city of Olathe, Kansas and until recently it also provided about 10 percent of the city’s drinking water supply. Taste-and-odor episodes have occurred periodically in Lake Olathe throughout the past 20 years and factored into the decision to discontinue use of the lake as a water supply. USGS studies in Lake Olathe indicated that taste-and-odor episodes were linked to both cyanobacterial bloom formation as well as actinomycetes bacteria (a group of taste-and-odor producing bacteria that live in soil) washed into the lake during runoff events.
The OGRL has a USGS approved GC/MS method for the analysis of the taste-and-odor compounds geosmin and 2-methylisoborneol (MIB). In addition, the lab currently analyzes for the cyanotoxin microcystin using enzyme-linked immunosorbent assays (ELISA). Methods are being developed for the LC/MS/MS analysis of cyanotoxins including microcystins, anatoxin, cylindrospermopsin, and β -methylamino alanine (BMAA).