Old Bavarian Donaumoos
... that the surface level of the Old Bavarian Donaumoos, once a bog covering 180 square kilometres (69 sq mi), has dropped by 3 metres (9.8 ft) since drainage began in 1790?
... that the surface level of the <b id="mwEiQ"><a href="./Old_Bavarian_Donaumoos" id="mwEiU" rel="mw:WikiLink" title="Old Bavarian Donaumoos">Old Bavarian Donaumoos</a></b>, once a <a href="./Bog" id="mwEiY" rel="mw:WikiLink" title="Bog">bog</a> covering <span about="#mwt60" data-mw='{"parts":[{"template":{"target":{"wt":"convert","href":"./Template:Convert"},"params":{"1":{"wt":"180"},"2":{"wt":"km²"}},"i":0}}]}' id="mwEic" typeof="mw:Transclusion">180 square kilometres (69</span><span about="#mwt60" typeof="mw:Entity"> </span><span about="#mwt60">sq</span><span about="#mwt60" typeof="mw:Entity"> </span><span about="#mwt60">mi)</span>, has dropped by <span about="#mwt61" data-mw='{"parts":[{"template":{"target":{"wt":"convert","href":"./Template:Convert"},"params":{"1":{"wt":"3"},"2":{"wt":"m"}},"i":0}}]}' id="mwEig" typeof="mw:Transclusion">3 metres (9.8</span><span about="#mwt61" typeof="mw:Entity"> </span><span about="#mwt61">ft)</span> since drainage began in 1790?