Bass Coast Post
  • Home
    • Recent articles
  • News
    • Point of view
    • View from the chamber
  • Writers
    • Anne Davie
    • Anne Heath Mennell
    • Bob Middleton
    • Carolyn Landon
    • Catherine Watson
    • Christine Grayden
    • Dick Wettenhall
    • Ed Thexton
    • Etsuko Yasunaga
    • Frank Coldebella
    • Gayle Marien
    • Geoff Ellis
    • Gill Heal
    • Harry Freeman
    • Ian Burns
    • Joan Woods
    • John Coldebella
    • Jordan Crugnale
    • Julie Statkus
    • Kit Sleeman
    • Laura Brearley >
      • Coastal Connections
    • Lauren Burns
    • Liane Arno
    • Linda Cuttriss
    • Linda Gordon
    • Lisa Schonberg
    • Liz Low
    • Marian Quigley
    • Mark Robertson
    • Mary Whelan
    • Meryl Brown Tobin
    • Michael Whelan
    • Mikhaela Barlow
    • Miriam Strickland
    • Natasha Williams-Novak
    • Neil Daly
    • Patsy Hunt
    • Pauline Wilkinson
    • Phil Wright
    • Sally McNiece
    • Terri Allen
    • Tim Shannon
    • Zoe Geyer
  • Features
    • Features 2022
  • Arts
  • Local history
  • Environment
  • Bass Coast Prize
  • Community
    • Diary
    • Courses
    • Groups
  • Contact us

Full and plenty

7/7/2017

2 Comments

 
Picture
While the periodic flooding of the Powlett estuary causes consternation to some local landholders, it's a time of full and plenty for water birds and freshwater fish.

By Catherine Watson
 
A COUPLE of visitors stood at the Mouth of the Powlett bridge yesterday and looked anxiously around. Water as far as the eye could see. The bridge was closed, the road on the other side submerged by the watery expanse.
 
“I haven’t seen it this bad for years,” said one gloomily.
 
“Wouldn’t you think they’d open the mouth!” said the other.
 
Which, as it happens, was exactly what a Parks Victoria contractor was doing at that moment, with a bulldozer shifting a sandbar that has blocked the river from reaching the sea for the past three months.
 
This year’s low autumn river flows, combined with a big swell, caused a build-up of sand that closed the mouth of the Powlett in late March with the estuary gradually filling in the months since then.

But the gloom of the two visitors was misplaced. Far from being a disaster, the periodic flooding is a time of full and plenty for water birds and freshwater fish, not to mention for birdwatchers and kayakers.
PicturePowlett Express, September 24, 1915
For neighbouring farmers and landholders it’s been a time of some anxiety, with frequent letters to local newspapers demanding that something be done. ​For more than a century, farmers on the floodplain have pressed the relevant government department to dredge the mouth of the estuary whenever it blocks.  
 
But a report prepared for the West Gippsland Catchment Management Authority (WGCMA) in 2008 concluded that the periodic closing of the mouth of the Powlett was essential to the health of the estuary and floodplain. Artificially opening the mouth could cause major problems. It recommended an opening once a year, if necessary, during late winter or early spring.
 
WGCMA CEO Martin Fuller says there are huge environmental benefits of the river mouth closing. “The wetlands are home to, and provide food for, many species of fish, birds and invertebrates. There is a flow-on effect when the river mouth closes. Algae begins to grow which provides food for insects and fish. The calm waters then turn into a fish nursery and with the increase in fish and insects birds come to feed.

“An increase in freshwater river flows can create a natural opening. This will also trigger fish migration both upstream and out to sea.”
​

But the catchment management authority also has to take into account the concerns of surrounding landholders. When the river mouth closes, monitoring begins to decide if and when an artificial opening should be attempted.
 
If the sandbar is opened under the wrong conditions, oxygen-rich water from the top of the estuary drains into the sea, leaving the oxygen-depleted water at the bottom, which can result in large fish kills. On top of that, it’s not always effective as the estuary mouth is more likely to reclose after an artificial than a natural opening.

For the past couple of months, staff and a team of local volunteers from EstuaryWatch have been testing temperature, oxygen levels and turbidity at selected sites along the estuary. 

The stars aligned yesterday with the right dissolved oxygen levels and tides, and rainfall predicted. By dusk, several hours after the opening, the water level had dropped considerably.

WGCMA’s Dan Garlick said the rate of draining depended on many factors. “It varies with each opening. The water can slowly recede or it can drop quite dramatically.”
While the expanse of water on the floodplain will recede, and the road to the Mouth of the Powlett will re-open, the estuarine billabongs with their teeming bird and fish populations will remain for some time.

For more information about the Powlett River Mouth, the estuary and the closure visit www.wgcma.vic.gov.au.

Visit Estuary Watch for more information and monitoring data from the Powlett River Estuary. ​

Picture
Photo: West Gippsland Catchment Management Authority
2 Comments
Sue Packham
8/7/2017 04:24:30 pm

I've only been a 'local' for 10 years. In that time the Powlett floods have been a joy for a nature lover with the influx of birds to the lake-like area. Landowners surely would have known of the floodplain's annual behaviour before purchase. If inherited then they would have absorbed the families' negative attitudes. Hopefully they're as impressed as I am with the care that's taken before artificially opening the river's mouth to the sea. From my observations the grasses have plenty of time to grow the Spring/Summer pastures - a rich brew for the grazing animals.

Reply
Mark Robertson
12/7/2017 09:32:14 am

Estuarywatch volunteers tested the river waters on monday arvo and found there to be good levels of dissolved oxygen at both bridges, along with a wide variety of waterbirds.

Reply



Leave a Reply.