▁and ▁are ▁home ▁to ▁some ▁extremely ▁rare ▁plant ▁and ▁animal ▁species . ▁ ▁The ▁Upper ▁Har z ▁P onds ▁also ▁have ▁the ▁oldest ▁working ▁d ams ▁in ▁Germany . ▁ ▁Pur pose ▁▁ ▁The ▁p onds ▁were ▁originally ▁built ▁for ▁storing ▁the ▁water ▁needed ▁to ▁drive ▁the ▁water ▁whe els ▁providing ▁energy ▁to ▁the ▁Upper ▁Har z ▁silver ▁mines . ▁These ▁water ▁whe els ▁drove ▁the ▁p umps , ▁the ▁ho isting ▁equipment , ▁the ▁stamp ▁mill s ▁and , ▁from ▁ 1 8 2 0 , ▁the ▁man ▁engines ▁as ▁well . ▁ ▁To ▁begin ▁with , ▁the ▁p onds ▁merely ▁imp ounded ▁water ▁from ▁their ▁natural ▁catch ment ▁areas . ▁But ▁in ▁many ▁cases , ▁their ▁in flow ▁was ▁later ▁increased ▁significantly ▁through ▁the ▁use ▁of ▁additional ▁collection ▁d itch es . ▁ ▁Today ▁the ▁p onds ▁are ▁operated ▁for ▁several ▁reasons : ▁the ▁protection ▁of ▁historic ▁monuments , ▁rural ▁conservation , ▁nature ▁conservation ▁and ▁recre ation . ▁Several ▁p onds ▁also ▁provide ▁flo od ▁protection ; ▁others ▁are ▁used ▁to ▁supply ▁drink ing ▁water . ▁ ▁The ▁operator ▁of ▁the ▁p onds ▁today ▁is ▁the ▁Har zw asser werke , ▁who ▁also ▁manage ▁six ▁modern ▁d ams ▁in ▁the ▁Lower ▁Sax on ▁part ▁of ▁the ▁Har z . ▁ ▁Design ▁ ▁The ▁bar riers ▁were ▁built ▁as ▁earth - fill ▁d ams , ▁the ▁fill ▁being ▁usually ▁exc av ated ▁on ▁site . ▁Usually ▁small ▁quar ries ▁were ▁established ▁in ▁the ▁terrain ▁ear mark ed ▁as ▁the ▁future ▁res er