River faces pres­sure of pol­lu­tion

Southern Gazette (South Perth) - - Perth -

THE Swan River is in bet­ter con­di­tion than many as­sume, but there is still work to be done, Swan River Trust act­ing gen­eral-manager Mark Cu­g­ley says.

“Over­all, it’s in good con­di­tion, based on the fact that peo­ple can con­tinue to swim along it, the amount of fish and it sup­port­ing a vi­brant dol­phin pop­u­la­tion,” he said.

The Trust works to con­trol ex­cess nu­tri­ents reach­ing the river, in­clud­ing a $3 mil­lion project at the Bayswa­ter Brook main drain, about 7km from the Perth CBD, where 150,000 river­bank plants may stop 1.3t of ni­tro­gen reach­ing the river each year.

Ni­tro­gen and phos­phates from fer­tilis­ers can cre­ate toxic al­gae blooms in hot weather, so the Trust’s Mid­land and Wil­son plants pump oxy­gen into the wa­ter to pro­vide refuges from the blooms for fish in the rivers’ up­per reaches.

Ellen Brook, about 10km north of the Mid­land plant, is the worst trib­u­tary for the pol­lu­tion, breaching short- and long-term re­duc­tion tar­gets in the past four years.

Mr Cu­g­ley said 14 other Swan River catch­ments were meet­ing 20-year tar­gets and that work would con­tinue with the catch­ments’ coun­cils, farm­ers, golf cour­ses and land­scap­ers to re­duce fer­tilis­ers, while other State Gov­ern­ment agen­cies would en­force the Swan and Can­ning Rivers Man­age­ment Act .

He said the rivers would con­tinue to be af­fected by a grow­ing pop­u­la­tion and a dry­ing cli­mate, so the Trust would con­tinue to ed­u­cate the public about the threats.

Down­stream, three screens will block any plumes dur­ing dredg­ing for a boat­ing basin soon to begin at El­iz­a­beth Quay in the Perth CBD.

Trust statu­tory as­sess­ment manager Jenifer Stritzke said mon­i­tor­ing had not in­di­cated any inflow of con­tam­i­na­tion from his­toric dumps among which the Quay was be­ing ex­ca­vated.

She said much of what came out from the large main drain ad­ja­cent to the Quay and into the Swan would have flowed from Lake Mon­ger, 4km north-west, which it­self was fed by smaller drains tak­ing road run-off from places as far away as Shen­ton Park.

Mark Cu­g­ley (top left), act­ing gen­eral manager of the Swan River Trust, says that the river, while in pretty good con­di­tion, will face ad­di­tional pol­lu­tion pres­sures as the city be­comes more de­vel­oped.

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