"It is a bad mill in a bad place," she said.
Uruguay will start presenting its case from September 21.
Argentina has called Uruguay's action a "flagrant violation" of a 1975 treaty.
It filed an application with the court in May 2006, blaming Uruguay of unilaterally authorising the construction of the mill.
Argentina said the treaty granted each country the right "to use the waters of the river within its jurisdiction".
|Opponents say the mill's pollutants are causing 'irreversible' damage [AFP]
The treaty also upheld the two countries' duty to "preserve the aquatic environment and in particular to prevent its pollution".
Cerruti said the mill was built in a densely populated area whose inhabitants are concerned about their health as they use the river for fishing, leisure and tourism.
"It smells like rotten eggs," Cerutti said, adding that residents had to deal with the "unbearable" smell of hydrogen sulphide spewed from the mill.
Since it started operating in November 2007, the mill has discharged 44 million cubic metres of effluent, Cerruti said.
"The pollution is starting to cause irreversible damage to the riverine eco-system," she said.
Ence, a Spanish company, had planned to build another mill on the Uruguay river, but it has changed its plans and sold its project, which is yet to be constructed at a site further away from the Argentinian border.
Botnia's paper mill is worth $1bn and has an annual capacity of one million tonnes of paper pulp.
The mill, the largest ever erected on the banks of the River Uruguay, has a projected life span of 40 years.
Cerruti said that it "would never have been authorised in Europe".
The ICJ, which considers disputes between nations, dismissed a bid by Argentina in July 2006 for an order suspending construction of the two mills.
In January 2007, it rejected an application by Uruguay for an order ending a blockade of a bridge across the river by Argentinian environmentalists that has been in place since 2006.