Floodplain Management

1. Overview

Local councils are responsible for managing flood-prone land in NSW with support from the Department of Planning and Environment (DPE), which provides specialist technical knowledge. Provisions within the Bombala, Cooma-Monaro and Snowy River LEPs and DCPs aim to manage development on flood prone land to minimise the losses to our community and to protect life and property. 

There are four urban areas in the local government area that have flood prone land - Cooma, Michelago, Berridale and Bredbo. The provisions in the Cooma-Monaro Local Environmental Plan 2013, Snowy River Local Environment Plan 2013 and this plan aim to protect human life and property. 

2. Berridale 

Berridale has areas of flood affectation along Myack Creek and Coolamatong Creek, where high creek flows overtops the channel banks and spreads over roads and property. Coolamatong Creek, which runs through the town, has minimal channel capacity and spreads onto main roads including Jindabyne Road and Myack Street, as well as low-lying properties.

Coolamatong Creek tends to cause less property flooding but can cause hazardous road flooding at several road crossings. Kosciuszko Road, which is a main arterial road providing access to Berridale and the NSW ski resorts, can also be flooded by Wullwye Creek/Myack Creek around 2km north-east of town.

As with other towns, there are various instances of overland flooding. The Average Annual Damage for Berridale is estimated to be $243,000.

3. Bredbo

Bredbo has relatively little flood affectation in smaller flood events, but in those events of 5% AEP and larger, the Bredbo River can cause widespread inundation of roads and properties in the southern portion of the town.

There is a second, smaller watercourse that passes through the town that causes hazardous road flooding at several locations and can isolate a section of the town. In very rare to extreme flood events, a high water level on the Murrumbidgee River can exacerbate flooding of the Bredbo River or even cause flooding of the township of Bredbo.

As with other towns, there are also localised instances of overland flooding. The Average Annual Damage for Bredbo is estimated to be $162,000.

4. Cooma

Cooma has significant flood affectation along sections of Cooma Creek and Cooma Back Creek, particularly in flood events of 10% AEP (annual exceedance probability) and larger. On Cooma Creek, property and road flooding occur when parts of the levee are overtopped, with the potential for severe flooding particularly around Sharp Street and Commissioner Street.

Cooma Back Creek also has the potential to flood roads and properties, with a flooding hotspot in the section of creek of north of Sharp Street which is subject to high risk flooding. There is a third creek flooding hotspot near the confluence of the two creeks, near Mulach Street. In addition to creek flooding, flooding occurs in the Polo Flat industrial area, and in some residential areas due to overland flow.

There is an existing flood warning system in Cooma that has a target lead time of ONE hour, managed by the Bureau of Meteorology and the SES. The Average Annual Damage for Cooma is estimated to be $4.7 million.

5. Michelago

Michelago has relatively little flood affectation compared to other towns, with most areas of Michelago Creek’s floodplain away from dwellings and roads. While in very rare events (eg. 0.2% AEP) very few dwellings are directly affected by creek flooding, there is potential for severe inundation across the town in the Probable Maximum Flood (PMF).

Flooding issues are limited to areas of overland flow adjacent to Ryrie Street and isolation of properties outside of Michelago due to roads cut due to flooding. The Average Annual Damage for Michelago is estimated to be $137,000.

6. Other Areas 

Areas which are considered to be flood prone will require a flood assessment and will be assessed on a case-by-case basis. Where the likely extent of the 1:100 Average Recurrent Interval flood event is known or ascertained, the provisions of this Clause will apply to a proposed development.

(the above information forms part of the Cooma-Monaro Shire Council Development Control Plan 2014 (Clause 6.4))

8. Bombala Flood Plain Risk Management Studies and Plans

The former Bombala Council undertook a Flood Study which informed a Floodplain Risk Management Study and Plan. 

Bombala has experienced major floods in the past, most notably in 1971, 1952 and 1983. As a consequence of these experiences, Council has adopted a policy of restricting development in low lying areas that are potentially vulnerable to flooding.

Nonetheless, current predictions of the extent of inundation in the 1% annual exceedance probability (AEP) flood indicate that most businesses on the northern or river side of the main street of Bombala (i.e., Maybe Street) would experience inundation. Residential dwellings in Caveat, Young and Therry Streets would also be flood affected. Hence, there is an existing flood problem that needs to be addressed.

Accordingly, it is appropriate, under the NSW Government’s Floodplain Management Program, to consider options for reducing the flood damages that could be experienced by residents of Bombala and to reduce the risk for loss of life. Specifically, the assessment should address the existing flood risk, along with considering planning measures to manage the flood risk to future development and any residual, or continuing flood risk which exists at Bombala.