Suspension to Water Sharing Plan for the Belubula Regulated Rivers Water Sources 2016

Reason for decision

Suspension to Water Sharing Plan for the Belubula Regulated Rivers Water Sources 2016

Clause 26

Background

The Belubula water source is currently in Drought Stage 3, exhibiting severe water shortage.

Due to ongoing drought and very low inflows. Carcoar Dam is less than 22 percent total capacity. Evaporation and transmission losses are also very high.

Clause 26 of the Water Sharing Plan specifies an end of system flow target of 10 ML/day. The Belubula river receives a high proportion of its flow from tributary inflows downstream of the dam. On average, only ten per cent of total annual flow in the river comes from dam releases, the remaining 90 per cent is derived from inflows from the tributaries. In the lower reaches of the river, groundwater extraction also reduces the river flow as the systems are highly connected. Belubula stakeholders understand the nature of the system and the limited capacity of Carcoar dam to deliver the annual water allocations. Historically during dry periods Water NSW and the stakeholders have informally agreed suspend the end of system target.

Attempting to fulfil environmental water provisions (end of system flow requirements) during the current drought could potentially consume all of the water in the Carcoar Dam by July 2020.

To preserve water for higher priority users it is necessary suspend the end of system flow provision until water availability improves.

During the development of the new Water Sharing Plan alternate rules for the end of system flows are be investigated.

Reasons for decision

Section 49B of the Water Management Act 2000(WM Act) enables all or part of water sharing plans to be suspended if the Minister ‘is satisfied that there is an extreme event in relation to a particular Basin management area or part of the Basin water resources’. An extreme event includes an extreme dry period. The NSW Extreme Events Policy details how water should be managed during these extreme events. The priority is to secure critical human water needs (including non-human consumption requirements that would cause high social, economic or national security costs if not met).

The extreme events policy framework sets out 4 stages of operations – from normal operations in Stage 1 up to critical drought or water shortage in Stage 4. The suspension of parts of a water sharing plan is listed as a management tool for Stage 3 and Stage 4 events.

Before suspending the operation of all or part of a plan, the Minister must obtain the concurrence of the Minister for Energy and Environment.

Belubula - suspension of planned environmental water provisions

The suspension of clauses 26 will allow available water to in Carcoar dam and inflows from tributaries below the dam to be utilised for high priority water users.

Benefits and Risks

This suspension formalises the operation of Carcoar dam during dry periods, as has been historically agreed between Water NSW and stakeholders.

The suspension of Clause 26 will ensure water is available for high priority water users on the Belubua. This suspension will also ensure Cadia mine, which is an important industry in the area will be able to continue operations.

There will be concern that suspending this rule will impact aquatic ecosystems in the Belubula. Historically Cod, Macquarie Perch, Golden Perch and Blackfish have been found in the Belubula River. In the lower reaches of the river, downstream of Canowindra, there are also a few wetlands which are generally in poor health.

To mitigate the impact of reduced end of system flows, a first flush rule will be adopted. This rule will ensure that environmental needs of the system are be satisfied before flows are made available to lower security water users from any future tributary inflow events.

While Clause 26 is suspended an end of system operating rule based on a “wet trigger” at Flyers creek will be trialled. The trigger reinstates the 10 ML/day end of system target following a defined period of increased flow at the Flyers creek gauge. This trigger rule is one of the rule options being considered for the new Water Sharing Plan.

The benefits of the proposed amendment substantially outweigh the risks.