Beverley Town Pool water quality glitch now solved
Released 19 May 2008
Studies by the Department of Water's Northam regional staff have revealed a link between unpleasant odours from the Beverley Town Pool on the Avon River, and the opening of the surface water control gates at Qualandary Crossing.
The water quality investigations followed public complaints earlier this month about the odour and black particles discolouring the pool.
Program Manager for the department's waterway assessment and investigation, Bernard Kelly, has given assurances that the pool water is improving and expected to return to normal following the next high rainfall event.
Mr Kelly said the lower water quality coincided with the opening, a week earlier, of the outlet to the chain of salt lakes known as the Yenyening Lakes system.
"The Qualandary Crossing gates are 25 kilometres upstream of the Beverley Town Pool and river travel time is usually about two to three days when there is reasonable river flow," Mr Kelly said.
"Our water sampling demonstrated that the pool contains sulphidic black ooze which, if undisturbed, will generally lie on the bottom. The samples also demonstrated low dissolved oxygen levels, elevated organic carbon levels and an increase in the concentration of nutrients.
"A flush of very salty water from upstream appears to have disturbed this ooze by releasing hydrogen sulphide gas and this has caused suspension of the fine black particles in the water.
In turn, the ooze has consumed the dissolved oxygen through the oxidation of iron sulphide, resulting in deoxygenation of the water and fish coming to the pool surface."
Mr Kelly said management of the gates is governed by the Yenyening Lakes Management Strategy, which authorises their opening when there is sufficient flow in the adjacent Avon River to "shandy" the lakes' waters with those of the river, so that impact on the downstream environment is minimised.
"In this case, it appears that the gates were inadvertently left open after checks were being carried out on the opening and closing mechanism," he said.
"Since this event, the department has been regularly sampling water quality, particularly for nutrients. The pool site is also included in the Department of Water's regular sampling regime of Avon rivers and tributaries conducted whilst there is stream flow.
"So far, salinity levels within the pool remain reasonably high, but nutrient levels are stabilising since the flush of water from the lakes has passed through, and dissolved oxygen levels have returned to normal. It is expected that these levels will be further diluted from stream flow following the next high rainfall event."
Further inquiries should be made to Bernard Kelly (08) 9690 2628 / 0407 196 601
Contact: Peter Collins
Phone: (08) 6364 6848 / 0434 603 441