Slovenia's natural environment suffers from damage to forests by industrial pollutants, especially chemical and metallurgical plant emissions and the resulting acid rain. Water pollution is also a problem. The Sava River is polluted with domestic and industrial waste; heavy metals and toxic chemicals can be found in the coastal waters. The country is subject to flooding and earthquakes. As of 2001, 5.9% of Slovenia's total land area was protected. In the same year, 10 out of 75 mammal species and 3 out of 207 breeding bird species were threatened, as were 3 plant species. Threatened species include the Italian agile frog, slender-billed curlew, Beluga, Danube salmon, and the olm.