Spain’s government activated a level 2 environmental emergency alert on Saturday over oil slicks that threaten pristine beaches on the southwestern Canary Islands.

The government activated the alert after analyzing ocean current data from Spain’s Oceanographic Institute, saying the slicks could affect the islands’ vulnerable coasts.

The islands are a popular destination for European visitors and harbor an important tourism industry.

The government said one beach had been cleared of oil and clean-up operations were ongoing on three other beaches near the tourist hot-spot of Maspalomas on Gran Canaria after a slick came ashore Thursday.

Regional authorities were criticized by environmental groups like Greenpeace after the Russian trawler Oleg Naydenov, which caught fire in a local port on April 11, was towed out to sea as a precaution. The boat, which carried 1,400 metric tons of a viscous type of fuel oil, sank on April 14, 24 kilometers south of the island.

Source: Appeal Democrat