See also
Design and operation of Yarrawonga Weir
Scoping Study Waterway Management Plan
Improved fish passage

Yarrawonga Weir

Yarrawonga Weir is located near the townships of Yarrawonga, in Victoria, and Mulwala, in NSW. Construction of Yarrawonga Weir began early in 1935 and was completed in 1939.

Yarrawonga Weir does not have a navigation lock as the River Murray Waters Agreement of 1915 provided for navigation upstream only as far upstream as Echuca. Nevertheless, the lake formed by the weir, Lake Mulwala, has become the focus of a valuable tourist and recreation industry for the area, with sailing, water skiing and fishing being the major water based activities.

A privately owned hydroelectric station and a fish lift were added to Yarrawonga Weir in 1994.

Purpose

The purpose of Yarrawonga Weir is to:

• raise water level in the River Murray so that gravity diversion is possible via major channels to irrigate land in both New South Wales and Victoria;
• regulate flows downstream, including the river reaches through the Barmah - Millewa forest and Echuca; and
• play a role in flood mitigation (although, due to the small volume of Yarrawonga Weir, effects on large floods are limited).

The Catchment

The major tributaries upstream of Yarrawonga Weir are the River Murray below Hume Dam, Kiewa and Ovens rivers.

Yarrawonga Weir is located 538 km from the source of the River Murray, and 1 992 km from the mouth. Travel times of flood peaks from the headwaters to Yarrawonga are 6 days, with a further 8 days to Echuca.

Average annual rainfall varies from about 2 000 mm over the mountainous area to about 500 mm near Lake Mulwala. The annual rainfall generally increases uniformly from north to south until the mountain ranges are encountered where it increases quite dramatically over short distances. A concentration of rainfall appears to occur over the Mt. Buffalo area.

Temperatures vary widely between seasons. During the summer season, temperatures above 40 degrees celsius are not uncommon throughout the flatter country at the northern end of the basin. In contrast, sub-zero temperatures are experienced in the southern mountainous region during the winter months.

At Lake William Hovell and at Lake Buffalo readings from evaporimeters indicate average annual gross evaporations of about 810 mm and 990 mm respectively.

To give an indication of evaporation from the flatter country to the north, the readings at Lake Mokoan could be considered representative. The average gross annual evaporation at this storage is about 1 240 mm.