Nipping Algal Blooms in the Bud
Toxic blue-green slime fouls Australian waters, clogging drains and raising havoc with humans, land, and beast
SYDNEY — EVERY summer in the small rural town of Blayney, New South Wales (NSW), a three-hour drive west of Sydney, the Belubula River used to look like someone dumped truckloads of pea soup into it. Other times its surface had a smelly green scum.
These days, thanks to a town-created wetlands project, the water is clear and swimmable.
What had happened to the Belubula River is typical of many of Australia's waterways and reservoirs: It was attacked by blue-green algal blooms. This condition occurs when microscopic blue-green algae multiply and fill lakes and rivers with foul-smelling green scum. Blooms clog water filters. When they die, they deoxygenate the water, which kills fish.
Some species of algae become toxic when they reach a certain density, killing livestock and making the water undrinkable and unswimmable.
``The dam we have here had the dubious title of being most polluted in NSW because of blue-green algal blooms,'' says Yvonne Goldie, the assistant chairman of the Carcoar Dam Catchment Management Committee.
In 1991, Blayney residents started agitating for help from the state government. The NSW Department of Water Resources funded a project that diverts the entire river through an artificial wetland that absorbs phosphates before the water reaches the dam. Town residents, including schoolchildren, helped build the wetlands by planting native trees and shrubs.
The first recorded toxic algal bloom was in 1878 on Lake Alexandrina in South Australia.
``Lake Washington in Washington State [US], Britain, Canada, Japan, China, South Africa, Germany, and Greece have all had toxic blooms,'' says Mike Burch, a biologist with the State Water Laboratory in Salisbury, South Australia.
``While there's no hard evidence yet, there's generally a sense that blooms are increasing in frequency and magnitude,'' says Martin Shafron, an environmental scientist with the Murray-Darling Basin Commission.
Blooms are a natural occurrence in Australia, because its flat topography and generally warm climate create slow-moving rivers. In addition, much river water is diverted into dams and reservoirs or used for irrigation.
Compounding the problem are excessive nutrients - phosphates from detergent, dumped treated sewage, farm runoff, forest runoff, and storm-water and irrigation drains. The combination creates a perfect breeding ground for blue-green algal blooms.
State and federal governments are making increasingly serious efforts to stop the problem. The Commonwealth (federal) government has allocated $30 million (Australian; US$20.4 million) to improve catchment management throughout Australia. (A catchment is all the land that contributes to a given stream.)
Another $3.1 million (US$2.1 million) was allocated to establish the first national ``Corridor of Green'' along the River Murray.
Lack of coordination between the states was another problem. The Murray-Darling Basin Commission was established in 1988 to coordinate river-basin management strategies between the states. An agreement for cooperative management of the region has been signed by the governments of the Commonwealth, NSW, Queensland, South Australia, and Victoria.
The NSW government announced a $2.3-million (US$1.5 million) contribution in August to help create more wetlands and vegetation buffers. The Commonwealth Science and Industry Research Organization (CSIRO) has been experimenting with aerators to add oxygen to the water.
``We're looking at how those things induce movement. You'll still get algae, but not toxic algae,'' says Gary Jones, senior research scientist at CSIRO.
Manufacturers are being asked to help. Detergent manufacturers signed an agreement last November with the NSW government limiting the amounts of phosphates in detergents to 5 percent.
Many of these efforts have come as a result of an enormous toxic algal bloom, believed to be the largest river bloom ever recorded, which occurred in Australia along the Darling/Barwon River system in late 1991 and stretched for some 600 miles through four states.
This event led to a state of emergency being declared in New South Wales for 22 days. In Queensland, several reservoirs had to be closed to recreation for up to three months, causing disrupted holidays and lost business. Water had to be trucked into some towns.
Because the quality of water in a given body reflects everything happening in the catchment, everyone from farmers to manufacturers to environmental groups to the government has a part in what happens to it.
``We all play a role in the problem part, so we should all be part of the solution,'' says Mr. Shafron. ``We've got to be able to compromise on the activities we do.''
Encouraging the pastoral industry to alter its habits is another aim, says John Verhoeven, manager of the environment branch of the NSW Department of Water Resources, who is also chairman of the state's Algal Coordinating Committee.
``It may mean a combination of keeping livestock out of the river, having their drinking water pumped away, planting vegetation buffer strips to intercept nutrient flow, and perhaps on the odd occasion, fencing off part of the river,'' he says.
In Blayney, the NSW Department of Water Resources has worked with the local community over the last four years in a multipronged approach to reducing the amount of phosphorous entering the water.
Nutrients came from an abattoir (cattle-slaughtering site). Cattle-station owners are now diverting their effluent to a land dump. The rural community has been improving its land-management practices. And the town itself is upgrading its sewage-treatment facilities.
``What you found in the beginning was [that] people were defensive; no one wanted the finger pointed at them. We've come a long way to, `This is the situation we have, how can we solve it?' '' Mrs. Goldie says.
``When you looked at it before, it was just a row of willow trees and a flood plain,'' she says. ``Now when you look down, you can see the wetland, some of the trees blooming, and lots of bird life.''