TRC prepares to re-open Cooby Dam’s Loveday Cove to recreation activities

Toowoomba Regional Council (TRC) is preparing to re-open Cooby Dam’s Loveday Cove for recreation activities as soon as practicable.

TRC Parks and Recreation Services portfolio leader Cr Tim McMahon said bacterial and algal toxin levels had returned to levels that allowed Council to prepare for the dam’s re-opening for recreational use, in line with Cressbrook and Perseverance dams. The recreation area at the Cooby Dam wall remains closed until further notice.

“Council has reviewed its dam recreation use guidelines and has adopted the National Health and Medical Research Council (NHMRC) guidelines,” Cr McMahon said.

“Adhering to these guidelines will reduce the frequency and duration of future dam closures, while continuing to manage the health risks to dam users.”

Cr McMahon said recent floods had caused what was believed to be a ‘blackwater’ event in Cooby Dam, which resulted in a large number of fish deaths. (*Blackwater events occur when flooding washes organic material into waterways, where it is consumed by bacteria, leading to a rise in dissolved carbon in the water. See more detail below. Source: www.waterquality.gov.au/issues/blackwater-events )

“Council officers have reported the event to the Department of Environment and Science and are continuing to investigate the cause of the incident, while cleaning up the dead fish in anticipation of re-opening the dam to the public,” he said.

“Further testing is being undertaken to determine the exact cause of the fish deaths, as we are not attributing it to the bacterial or algal levels at this stage. We also do not suspect there is any chemical involved.

“Species involved include eel-tailed Catfish, Yellowbelly, shrimp and some Murray cod.”

TRC Water and Waste Committee chair Cr Rebecca Vonhoff said Lake Cressbrook was the primary source of the water that was being treated and distributed to residents connected to the Toowoomba Bulk Water Supply network.

“Council has been taking water from Lake Cressbrook since the February rain event and continues with its regular water quality testing,” Cr Vonhoff said.

“No water quality issues have been identified at Lake Cressbrook or Perseverance Dam,” Cr Vonhoff said.

To view activities that are open or closed at the dams, please visit www.tr.qld.gov.au/damstatus 

Background: Blackwater events Rising levels of dissolved carbon cause a sudden depletion of dissolved oxygen in water, which is essential for aquatic organisms that need to breathe underwater.

Less frequent flooding leads to the accumulation of larger quantities of organic material on river banks and floodplains. When this debris is washed into the waterway during a flood, bacteria consumes the organic matter, releasing carbon and depleting the levels of dissolved oxygen in the water. This process is more pronounced during summer flooding.

Blackwater usually has short-term harmful impacts on the environment. Low levels of dissolved oxygen, combined with the toxic components of some organic matter, can lead to the localised death of aquatic organisms.

Native fish and crustaceans are especially vulnerable to oxygen deprivation, although fish are sometimes able to escape the most badly affected areas by swimming upstream or downstream.

Chemicals released from organic material can also make water bodies more alkaline or acidic, potentially disrupting normal pH balances and resulting in toxic effects on some aquatic organisms.

Despite short-term negative effects on aquatic organisms, the floods which lead to blackwater are an essential and valuable requirement for the long-term health of river, floodplain and wetland ecosystems, particularly after prolonged drought.

These events help break down organic material which supply additional carbon and nutrients to drive overall production in river and wetland systems.

Native fish, waterbirds and other organisms benefit from increased production, because it: • boosts food supplies • supports breeding cycles.

Human health risks are low if you: • avoid direct contact with blackwater • do not eat discoloured or dead fish.

(Source: www.waterquality.gov.au/issues/blackwater-events )