TORRES, Brazil — A mayor in southern Brazil asked residents to ration water Tuesday in a state capital where some 80% of the population is without running water, a week after massive flooding that has left at least 90 people dead and more than 130 missing.

Efforts were continuing to rescue people stranded by the f loods in the southern state of Rio Grande do Sul, as more rains were forecast for the region into next week. The capital, Porto Alegre, has been virtually cut off, with the airport and bus station closed and main roads blocked due to the floodwaters.

Five of the city's six water treatment facilities aren't working, and Porto Alegre Mayor Sebastião Melo ordered that water be used exclusively for ''essential consumption.'' Local shops have also been short on water supplies.

''We are living an unprecedented natural disaster and everyone needs to help,'' Melo told journalists. ''The shortage is real and it will take some time until it goes back to normal."

''I am getting water trucks to soccer fields and people will have to go there to get their water in bottles. I cannot get them to go home to home,'' the mayor added.

The most urgent need is drinking water, but food and personal hygiene products are also in short supply. Other Brazilian states are mobilizing trucks with donations bound for Rio Grande do Sul.

Residents in Rio Grande do Sul who are able to flee are doing so, over fears of shortage and the spread of disease. However, it's difficult for many to leave Porto Alegre with main access roads blocked by floodwaters. The city's airport and main bus terminal are filled with water and closed for the foreseeable future.

The downpour has stopped for now, but a looming cold front will bring more severe rain starting Tuesday night, mainly in the southern part of the state, according to the National Meteorological Institute. Rainfall is could exceed 150 millimeters (5.9 inches) by early Wednesday.

Late Monday, Rio Grande do Sul's Gov. Eduardo Leite issued an alert for several cities close to the massive Patos Lagoon. The floodwaters in Porto Alegre and other cities pass through the lagoon to the sea.

''The water level will rise and it will affect you,'' he said in a video broadcast on his social media channels. ''Please, believe the alerts and help us save lives. Let's reduce the damage so we can be together to rebuild.''

Damage from the rains has already forced more than 150,000 people from their homes. An additional 50,000 have taken refuge in schools, gymnasiums and other temporary shelters.

Brazil's President Luiz Inácio Lula da Silva visited Rio Grande do Sul for a second time on Sunday, accompanied by Defense Minister José Múcio, Finance Minister Fernando Haddad and Environment Minister Marina Silva, among others.

During Mass at the Vatican on Sunday, Pope Francis said he was praying for the state's population.

Public health experts say there is growing risk of disease as much of the region remains underwater, warning that cases of dengue fever and leptospirosis in particular could rise sharply within days

Security is another concern. Rio Grande do Sul's public security secretariat said in a statement that police will beef up operations to prevent looting and theft. Several volunteers working on rescue operations have been robbed as they tried to help in the Porto Alegre metropolitan region.

Also on Monday, three top-tier Rio Grande do Sul state soccer clubs whose stadiums are flooded urged Brazil's soccer federation to suspend their national league matches for the next 20 days because of the flooding. Brazil's soccer confederation said it would consider the request.

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AP journalist Gabriela Sá Pessoa contributed from Sao Paulo.