The environmental institute found that 48 percent of all the samples it collected in Italy's 15 coastal regions show signs of pollution.
Goletta Verde's team of scientists analyzed more than 300 samples of water from along Italy's coastline and found that 39 percent were "heavily polluted," while a further 9 percent also showed signs of substantial pollution.
Lack of sewage treatment is the main cause, states Legambiente's final report. "Poor purification is, in fact, an environmental emergency that must be tackled urgently since we have also been ordered to pay a fine of 25 million euros to the EU, plus 30 million every six months until we are in good standing," Giorgio Zampetti, Legambiente's director, said in the statement.
The mouths of rivers are the points where the highest levels of pollution were identified. Of 149 examined, 106 resulted polluted.
The coastline in Liguria, Tuscany and Sicily are the most polluted, according to a map by Legambiente which outlines the results. The waters around the island of Sardinia are the cleanest. The Legambiente results from 2018 show an 8 percent increase in pollution since 2017.
Legambiente's report covered the entire expanse of Italy's coastline – islands and peninsula – but focused on "abandoned waters," or 170-kilometres of coast where 556 watercourses run into the sea but are not regularly monitored by Italy's Ministry of Health, according to the environmental activists.
Legambiente also launched the #NoOil campaign, which aims to pressure Italy's Minister of Economic Development Luigi di Maio to stop the extraction of fossil fuels.
"In our seas, research and extraction activities of hydrocarbons put at risk over 120 thousand square kilometres: there are 67 production concessions, 138 oil rigs and 24 exploration permits to which a further 34 could be added," states Legambiente.
Beach areas are similarly polluted, according to the results. Of 78 beaches examined (the equivalent of 60 football pitches), 50,000 items of waste were identified – 620 every 100 metres. Some 80 percent of all the waste was plastic. Plastic bottles, bottle tops, dishes and plastic bags were the most prominent waste items.
In at least eight areas where swimming is officially banned, the organisation found that only one had signs on display to warn people not to enter the water.
Since the beginning of 2018, Legambiente volunteers have cleaned up 500 Italian beaches.