Sustainability Report 2006/07Challenges of a very dry year
Extreme drought conditions continued across the Port Phillip and Westernport region, affecting waterways and wetlands.
The Yarra River Environmental Water Reserve had to be deferred to safeguard drinking water supplies, while other waterways experienced extreme low flows.
Habitat availability for fish and other aquatic species was reduced, increasing pressure through increased competition and predation. This includes platypus populations, where decreased streamflows reduce available food and habitat.
We reviewed the impact of drought on fish populations in Diamond Creek, and identified a pool on Arthurs Creek that was serving as critical refuge for populations of threatened fish species such as blackfish. We released extra flows from Running Creek Reservoir in the upper catchment, helping to prevent loss of local fish populations.
The Ramsar-listed Edithvale-Seaford wetlands dried up much earlier than usual during the 2006/07 summer period, and bird numbers fell significantly, with migratory species in particular in record low numbers.
Conversely, the Ramsar-listed wetlands at the Western Treatment Plant had extremely high numbers of birds in the 2006/07 season due to the guaranteed water supply creating an important drought refuge.
Some revegetation works have failed due to the lack of rain. In several river health improvement projects, plantings were deferred to reduce losses.
The drought delayed planting on new wetlands, which has contributed to Melbourne Water failing to meet nitrogen removal targets for Port Phillip Bay.
However, the drought assisted capital works by extending conditions that enabled access for machinery to the bed and banks of creeks.
Farmers, landholders and other water diverters with licences to extract water from waterways for farming, irrigation, orchards and other agricultural business have faced severe restrictions, and in some cases have had zero water allocations. In the Maribyrnong catchment, diverters faced bans for nine months from October 2006.