▁o xygen ▁and ▁increasing ▁ph osph orus ▁concentr ations ▁means ▁it ▁is ▁unclear ▁if ▁the ▁lake ▁will ▁recover . ▁ ▁The ▁Federal ▁Office ▁for ▁the ▁Environment ' s ▁last ▁published ▁report ▁on ▁Lake ▁L ug ano ▁dates ▁from ▁ 1 9 9 5 . ▁To ▁summar ise ▁that ▁report : ▁ ▁at ▁that ▁time ▁measurements ▁indicated ▁some ▁improvement , ▁but ▁this ▁was ▁unlikely ▁to ▁continue ▁at ▁the ▁same ▁pace ▁ ▁there ▁were ▁almost ▁permanent ▁poll uted ▁layers ▁at ▁the ▁bottom ▁of ▁the ▁very ▁deep ▁lake ▁ ▁o xygen ▁was ▁scar ce ▁and ▁could ▁not ▁be ▁found ▁below ▁ ▁depth ▁ ▁as ▁a ▁result ▁ph osph orus ▁levels ▁were ▁increasing ▁at ▁this ▁depth ▁ ▁ph osph orus ▁levels ▁in ▁the ▁northern ▁bas in ▁were ▁six ▁times ▁too ▁high ▁and ▁in ▁the ▁southern ▁bas in ▁twice ▁too ▁high ▁ ▁will ▁take ▁many ▁dec ades ▁to ▁clean ▁ ▁the ▁lake ▁could ▁be ▁said ▁to ▁be ▁" chron ically ▁sick " ▁ ▁in ▁the ▁Italian ▁part ▁of ▁the ▁lake ▁only ▁ 2 0 % ▁of ▁the ▁population ▁were ▁connected ▁to ▁se w age ▁treatment ▁plants ▁with ▁ph osph orus ▁filters ▁( not ▁that ▁all ▁Swiss ▁areas ▁were ▁connected ▁either ). ▁ ▁The ▁Swiss - Ital ian ▁organisation ▁C IP A IS ▁in ▁its ▁most ▁recent ▁published ▁report ▁says : ▁ ▁The ▁Italian ▁environmental ▁group ▁Leg amb iente , ▁in ▁its ▁ 2 0 0 7 ▁study ▁of ▁all ▁northern ▁Italian ▁la kes , ▁found ▁Lake ▁L ug ano ▁to ▁be ▁the ▁most ▁poll uted ▁of ▁all .