It could take months to evaluate the extent of damage to a river left choked with mud when a dam burst at an iron ore mine, Brazil's environment minister said Wednesday.

Izabella Teixeira said that rains could further complicate the task of recuperating the Doce River, which filled with huge quantities of mud unleashed by the Nov. 5 dam burst in the southeastern state of Minas Gerais.

"We will have to wait until the end of the rainy season to evaluate what is going on," Teixira said on state-run television, referring to the country's December to March rainy season. "We are going to monitor the concentration of mud that keeps arriving."

The flood of mud unleashed by the dam burst at the Samarco mine all but erased a nearby hamlet, with eight deaths directly attributed to the disaster, another four bodies yet to be identified and another 11 people still missing. The wave spilled into the Doce River, where it has devastated fish and other wildlife and compromised the source of drinking water for hundreds of thousands of people.

The destruction spread over the weekend into the ocean as the plume of mud reached the Atlantic, hundreds of kilometers (miles) from the site of the accident. The plume has spread many kilometers out to sea, tinging the sapphire waters the color of chocolate milk and threatening marine life there.

The area of coastline, in the north of the Espirito Santo state, encompasses the Comboios Biological Reserve, a spawning area for the critically endangered leatherback sea turtles. It's the peak of the animal's reproductive season.

In a statement over the weekend, Samarco, the mining company behind the dam burst, said it was installing "9,000 meters of barriers along both banks of the Doce River and at some islands in the estuary, with the objective of protecting the fauna and flora which inhabit these regions." However, aerial photos of the area show the brown waters bleeding through the barriers.

Samarco is jointly owned by two mining giants, Brazil's Vale and BHP Billiton of Australia.

The Brazilian government has already handed Samarco a fine of around $260 million, though environmentalists say the damage amounts to many times that sum.

In a statement Wednesday, two United Nations independent experts on environment and toxic waste took the companies and the government to task on their handling of the disaster.

"The steps taken by the Brazilian government, Vale and BHP Billiton to prevent harm were clearly insufficient," the statement quoted UN Special Rapporteur on human rights and the environment, John Knox, and the Special Rapporteur human rights and hazardous substances and wastes, Baskut Tuncak, as saying.

"The scale of the environmental damage is the equivalent of 20,000 Olympic swimming pools of toxic mud waste contaminating the soil, rivers and water system of an area covering over 850 kilometers," Knox is quoted as saying.