Griffith City Council’s Floodplain Management Committee have discussed a range of responses to the Main Drain J and Mirrool Creek Floodplain Risk Management Study and Plan.

The study was made public earlier this year and considered various factors behind the 2012 floods which inundated Yenda and surrounding areas.

A submission from the Yenda Progress Association recommended installing a “Lawson” syphon as a “permanent and proper solution to prevent Yenda being flooded again.”

The Lawson Syphon was built at Deniliquin after WWII and allows 2.4 gigalitres of water to flow nearly a kilometre underground every day.

The study listed the syphon as a flood-proofing alternative to reinstating the East Mirrool Regulator floodgates.

According to Councillor Paul Rossetto, the NSW government played a significant role in decommissioning the floodgates in the early 1990s.

Flooding of Yenda in 1939 and 1989 was avoided because of the floodgates, according to the study, but the 2012 event would have exceeded both the floodgates and a siphon.

Mayor John Dal Broi said it was important to reach an understanding with Murrumbidgee Irrigation (MI) and the State Emergency Service (SES) on how to deal with a similar event if one was to occur before flood mitigation technologies were installed. 

“If we have a similar event the only avenue for us to take the pressure off the northern branch canal is to breach the main canal,” Cr Dal Broi said.

“We’d get an excavator in there and open it up and send it down to Mirrool Creek. If you flood a crop you can plant it again. If you flood a house you have to build it again.”

On Saturday, March 3 2012, heavy rain hit southern NSW. Just over 133mm fell on the MIA, flooding Yoogali and Hanwood. Barellan and Ardlethan also took a soaking like never before. That night, the SES established an emergency operations centre (EOC) in Griffith.

On Sunday, March 4, a decision was made to breach the canal at Roaches Regulator near Leeton. 

There had also been a proposal to breach the canal system near Yenda where Mirrool Creek meets the main canal and the northern branch canal but EOC officials were concerned about potential impacts on Yoogali, parts of Griffith and Hanwood.

The bank of the northern branch canal collapsed on Monday night, resulting in the flooding of Yenda. 

The SES believed about 125,000 megalitres of water passed through Mirrool Creek throughout the flood event.

Have a look at the final floodplain report here.