VICTORIAN rivers and streams are in a state of decline and pose serious threats to human health thanks to an unpleasant culprit: cow poo.

Monash University research has renewed concerns about the poor condition of rivers, which environmentalists say are suffering due to ''Third World management'' of public land.

Uncontrolled cattle access to rivers can affect water quality.

The latest research, to be released today, confirms long-held fears that grazing cattle damage rivers by leaving waste in the water, as well as increasing the potential for toxic algae blooms. It also notes uncontrolled cattle access to rivers can affect water quality due to pathogens in cow faeces. While many towns have water filtration systems to remove these, some do not, putting people at risk of health problems.

The report, Riverside Rescue, was commissioned by the Victorian National Parks Association to coincide with World Rivers Day, today. It comes as the Baillieu government faces growing pressure to boost its environmental credentials after widespread criticism over issues such as the state's 20 per cent emissions reduction target, cattle grazing in the Alpine national park, and restrictions on wind farms.