Temporary Water Restriction - Northern Basin Floodplain Harvesting

Reason for Decision

Temporary Water Restriction (Northern Basin)(Floodplain Harvesting) Order 2020

Overview

The Bureau of Meteorology (BOM) has forecast widespread heavy showers across NSW for the coming days that have the potential to cause runoff and flash floods by the end of the weekend (8-9 February). Most of the rain will be centred on the NSW North Coast. The extent of rainfall in northern inland NSW is less certain, and is predicted to occur mainly via storm events. This may result in patchy, high intensity, localised falls. The predicted rain is due to a slow moving high pressure system in the Tasman Sea that is currently directing easterly winds onto the NSW and south-eastern Queensland coasts. This will combine with an upper level low over western NSW by the the weekend of 8-9 February. A surface trough is likely to establish along the coastline of NSW that may to bring intense bursts of heavy rain to parts of NSW and south east Queensland. These rain events may lead to overland flow and localised flooding.

Rain in the northern NSW Murray Darling Basin in late January mostly resulted in short, sharp inflows into some river systems, with no persistent flows. The exception was in the upper Namoi and Peel catchments. In these areas, from 26 January until 7 February limited access was permitted for high security access licences in the Peel Regulated River Water Source and for unregulated access licences in the Mooki River and Quirindi Creek water sources.

This rain has also resulted in many of the northern NSW Murray Darling Basin systems being primed to flow should follow-up rain occur with average to above average soil moisture across some of the northern areas.

Protection of overland flows resulting from this follow-up rain is in the public interest, due to the ongoing severe drought conditions. It ensures local critical needs (town water, domestic and stock, basic landholder rights, and critical drought refuge areas) are met from resulting inflows to the rivers, and will improve the likelihood of flows from this and subsequent events reaching the Barwon-Darling and Lower Darling river systems.

This temporary restriction order will apply to the take of water for the purpose of floodplain harvesting, except in the case where the take of water is by a work for the purpose of a tailwater return system. Take of rainfall runoff from irrigation fields with tailwater return drains will be exempt from the restriction, as this water is likely to be contaminated and irrigation properties are designed to retain this form of runoff. The passive take of water is also exempt where the nature of the floodplain harvesting work means that the take of overland flow cannot be reasonably prevented.

This order does not apply to the take of water for basic landholder rights (including harvestable rights).

Due to the unpredictable nature of where the rain will fall, and to what extent, the restriction will apply to the following northern NSW floodplain catchments:

  • Barwon-Darling Valley Floodplain,
  • Gwydir Valley Floodplain,
  • Lower Namoi Valley Floodplain (as designated and amended under the Water Act 1912, Gazette No. 164 of 23.12.2005, p11253 and Gazette No. 139 of 28.09.1984, p 4848),
  • Narrabri – Wee Waa Floodplain (as designated under the Water Act 1912, Gazette No. 164 of 23.12.2005, p 11253)
  • Narromine to Oxley Station Floodplain (as designated under the Water Act 1912, Gazette No. 155 of 5.12.2008 and sometimes referred to as the Macquarie Valley Floodplain),
  • Upper Namoi Valley Floodplain.

This temporary restriction is to apply from Friday 7 February up to and including Friday 28 February 2020.

The order provides for active management. That is, should substantial overland flows occur, and the river flows generated are in excess of that required for critical needs in the northern tributaries or downstream river systems, the Department can approve the take of water for floodplain harvesting. Rainfall and inflows will be closely monitored during this period to determine if a repeal, amendment or advice to customers allowing access is needed.


Background

In times of extreme drought, protecting water supply for critical needs is a key priority. All northern regulated valleys, and both the Barwon-Darling and Lower Darling, are in Stage 3 severe or Stage 4 critical drought. Inflows into the Barwon-Darling River and the major northern storages are at record low levels, despite recent rainfall events.

Having a temporary restriction order on floodplain harvesting take allows resulting flows to rivers to be protected for critical needs.

Town water supplies remain at low levels across much of the north-west and far west of NSW.  Many towns such as Walgett and Mungindi could potentially be out of river water in the next few months if no or only low inflows occur into the major storages. Towns downstream of Tilpa (Wilcannia and Menindee) did not receive inflows from the November 2019 rain event. It is essential that all inflows are protected for these higher priority critical town supply needs.

The overarching aim of the restriction is to ensure that critical needs (town water supply, basic landholder rights, high security requirements and environmental needs) are met if inflows result from overland flows following the extended dry period – both in local river valleys, and if possible downstream in the Barwon-Darling and the Lower Darling. Placing a temporary water restriction order on floodplain harvesting is a way to achieve this aim.

Reasons for Decisions

Temporary water restriction – section 324

Section 324 of the Water Management Act 2000 (the Act) allows the Minister or delegate to order that temporary water restrictions within a water source(s) are to have effect for a specified period, if these restrictions are determined to be in the public interest.

Examples of the public interest referred to in section 324(1) include “to cope with a water shortage, threat to public health or safety or to manage water for environmental purposes”.

Based on the information outlined in the Background section, there is a public interest in making an order to restrict take as follows:

  • “To cope with a water shortage” - Remaining water supplies in the north-western catchments are at very low levels. The north-western regulated river systems, the Barwon Darling and the Lower Darling are at Stage 3 (severe) or Stage 4 (critical) water shortage under the NSW Extreme Events Policy, and flows must be protected for critical human needs. Replenishment flows to many systems have not occurred for some time for domestic and stock purposes and water is being carted to many areas.
  • “Threat to public health and safety” - Town water supplies are reaching low levels across much of the north-west and far west of NSW. Many towns could potentially be out of river water in the next few months if there is no or low inflows to storages. Similarly, many creek systems in these valleys have not had full replenishment flows to meet domestic and stock needs, and water is being carted for these purposes. It is essential that all inflows are protected for these higher priority critical needs.
  • “Manage water for environmental purposes” Low flow conditions persist across most of the northern NSW Murray-Darling Basin. As the drought continues and the river system becomes increasingly disconnected, floodplain wetlands and pools that provide critical refuge for aquatic biota are drying up. The quality in remaining pools is declining, putting native fish (and other aquatic biota) at risk.

Prior to some local rain in 2019 and the 2019 northern fish flow event, the Barwon-Darling River had not flowed since August 2018. There are still sections of the river that have not flowed since then.

Critical wetlands and habitats across the northern basin are heavily impacted by the current drought. Only limited flows below Warren have been provided as a result of rainfall in mid-January.

If there are sufficient flows, the temporary water restriction will assist with the replenishment of floodplain wetlands and pools in the inland northern rivers that provide refuge for fish and other aquatic species, contribute to connectivity, and improve water quality. Protecting any upstream flows should they occur will also enhance the prospects of water reaching Menindee.

Flows and conditions will be monitored. Water users will be kept up to date on the prospects of water access through water user platforms.

Vanessa O'Keefe

A/ Executive Director, Water Policy, Planning and Sciences

7 February 2020