The irrigation industry is facing substantial change that is likely to affect the quantity and

timing of water supply, as well as the infrastructure involved in water delivery and use.

Effective adaptation to this change while ensuring environmental sustainability requires

knowledge of the effects of irrigation practices and landscapes upon local and regional

biodiversity, and the potential implications of predicted policy, supplier and farm changes.

Here we report on a three year project conducted by CSIRO in collaboration with the

Ricegrowers Association who have been conducting an Environmental Champions Program

since 2005. This program aims to assist landholders to improve environmental and economic

returns of their farm businesses and also allows them to be recognised for their past, current

and future environmental stewardship at an industry level.

Irrigated agriculture in Australia’s Riverina consists of a variety of industries - rice, cereal,

pulse and oilseed production, as well as livestock. Rice is the dominant crop, and is reliant

on irrigation water supply from the Murray and Murrumbidgee Rivers, supplemented in some

cases by underground water. Riverina irrigators are currently experiencing unprecedented

restrictions on production due to water shortages. The current drought, together with the

ramifications of the NSW environmental flow legislation of 1997, has resulted in irrigators

receiving only a fraction of their water allocations. The Riverina’s irrigation industries have

significantly improved water use efficiency over the past 20 years through research and

improved irrigation layouts. Given recent climate change projections, and increasing pressure

on water supplies, the need for even more efficient use of irrigation water in the future is

certain. Options for reducing water use are being implemented or canvassed at both the

enterprise and supply scales. Examples include changes in the cropping mix at an enterprise

level, reduction or cessation of flooding of rice crops, fewer crops and more efficient water

use. At the regional scale, changes to the nature of supply channels are possible, while the

application of more efficient techniques may result in less drainage being received in regional

wetlands.

Water is as significant a resource for native plants and animals as it is for people. Before

irrigation development the Riverina was semi-arid plain, with a range of shrubland,

grassland, woodland, forest and wetland vegetation. With the advent of the Snowy River

Scheme, and the resulting establishment of the Murrumbidgee, Coleambally and Murray

Irrigation Areas, new landscapes have been created incorporating irrigation infrastructure,

intensive farming in the form of broad-acre crops and horticulture, and significantly, a large

change in the temporal availability of water. The removal of native vegetation has adversely

impacted some of the original ecosystems, but it has also created opportunities locally for

wetland species and regionally for some wetland birds. In addition, some terrestrial biota

may well benefit from the extra resources associated with irrigation waters, despite some

losses of habitat vegetation (e.g. some species of birds). Interest in biodiversity was not part

of the original irrigation development agenda, and overall impacts are not well understood.

In recent times there has been more of a focus on protecting and enhancing remaining

biodiversity through Landcare, Land and Water Management Plans and industry initiatives

such as the Rice Industry’s Biodiversity Strategy and Plan. However the concern now is that

future changes in farming and water management practices do not further compound any

impacts that have already occurred.

The overall aim of this project was to assess the possible impacts of changed irrigation

practices on native biodiversity at local and regional scales, using the irrigation districts of

the New South Wales Riverina as a case study.