Outside the semi-arid area of the north-east, Brazilians have never had to worry about conserving water. Year in, year out, the summer has always brought rain.

But that has changed dramatically. São Paulo, the biggest metropolis in South America, with a population of almost 20 million, is now in the grip of its worst drought in more than a century – a water crisis of such proportions that reports on the daily level of the main reservoir arefollowed as closely as the football results.

The lack of rain is also affecting the dams that produce most of Brazil’s energy, highlighting the urgent need to diversify power sources.

And yet the state governor, wary of the effects on his prospects in forthcoming elections, has refused to introduce measures to ration, or even conserve, water.

Mighty rivers are running dry

Brazil is blessed not only with the mighty Amazon and all its huge tributaries, but also with dozens of other lengthy, broad rivers – once the highways for trade and slaving expeditions, but now providing waterways for cargo, power for dams, and water for reservoirs. It has at least 12% of the world’s fresh water supply.

But five of the principal rivers – the Tiete, Grande, Piracicaba, Mogi-Guaçu and Paraiba do Sul – that cross or border São Paulo, Brazil’s wealthiest state, have less than 30% of the water they should have at this time of year, according to data from the regional Hydrographic Basin Committee and from the National Electric System Operator (ONS).

Other major water sources – such as the Paraná, South America’s second biggest river, and the Paranapanema – are also suffering from the long dry period. The ruins of towns flooded for dam reservoirs have reappeared, fishermen’s boats are beached because the fish have disappeared, and navigation is at a standstill.

The transport of grain and other cargos to the port of Santos, via the river network, had to be suspended after the water level fell by up to eight metres. The equivalent of 10,000 lorryloads of cargo have been transferred by road so far.

Many industries have suspended their activities because of lack of water, and the drought has resulted in the loss of part of the coffee, sugar cane and wheat crops in one of Brazil’s most important agricultural states.

The hydrological period lasting from October 2013 to March 2014 was the driest for 123 years, according to the Agronomic Institute of Campinas, the oldest institute of its kind in Latin America.

Lowest water volumes since the 1930s

The federal government’s energy research company, EPE, found that in the first three months of 2014 the volume of rain was the third lowest since the 1930s.

It was the third consecutive year of reduction for the reservoirs of the hydroelectric dams that make up the South-east / Centre-West System, where many of Brazil’s biggest cities are located. From 88% in 2011, the volume of water in them had fallen to 38% by April 2014 – the month in which the dry season begins in this region.

By mid-August, the reservoirs of the Cantareira system, which supplies the water for almost 8.5 million of São Paulo’s inhabitants, had fallen to just 13.5% of capacity.

Yet the state government of São Paulo has so far refused even to admit that there is a crisis. The problem is the October elections, when Governor Geraldo Alkmim is running for re-election. Like most politicians, he does not want to be associated with a crisis. The word ‘rationing’ is taboo.

Instead, unofficial rationing – what might be called rationing by stealth – is in operation. At night, the São Paulo Water Company, Sabesp, is reducing the pressure in the water system by 75%, leaving residents in higher areas of the city with dry taps.

People before power? Electricity generation under threat

Over 80% of the country’s energy comes from hydroelectric power, and dozens more giant dams are under construction or planned, mostly in the Amazon basin. The government has been strangely reluctant to invest in, or even encourage, other sources of abundant renewable energy, such as wind, solar and biomass.

The over-reliance on hydropower has already led to a distortion. The back-up system of thermo-electric plants, run on gas and diesel, and designed for emergencies, has had to increase production from 8% in 2012 to cover 25% of energy demand this year – thus contributing to higher carbon emissions.

Politics have also interfered with the special crisis committee set up to monitor the drought situation, with representatives from local and federal agencies unable to agree on what to do.

The Sao Paulo energy company, CESP, unilaterally decided this month to reduce the volume of water released from the shared Jaguari reservoir to the neighbouring state of Rio de Janeiro for electricity generation, in order to keep more for its own water needs.

Dangerous precedent

For Marcio Zimmerman, executive secretary of the Ministry of Mines and Energy, CESP’s action creates a dangerous precedent. “There will be chaos if everyone decides to rebel against the ONS”, he said.

The realisation that climate change is already leading to major changes in weather patterns has sounded alarm bells among the business community about the need to diversify energy sources and conserve water.

Early this month, at a seminar organised by the Brazilian Business Council for Sustainable Development, the chief executives of more than 20 top companies drew up a list of 22 crisis-related proposals to be put to the presidential candidates in October’s election.

Newspaper editorials are now urging the politicians to take their heads out of the sand and involve the population in a serious discussion on the crisis and its effects on the water supply, energy generation, and food production .

The Rio newspaper O Globo declared: “They belittle the potential for efficiency available in a society accustomed to waste. When they act, it might be too late.”

Jan Rocha is a journalist living in São Paulo. She writes for Climate News Network, where this article originates.