Well, becauseofthisdamsarenotgreatfortheenvironmentaroundthembecauseputting a wallupinthemiddleof a rivertendstodisrupttheecosystem, includingofcoursethemigrationofsalmon.
Anditreallywasn't untilwewentthrough a verylargedamconstructionerainthetwentiesthirties, fortiesandfiftiesthatwebegantoseecumulativelytheimpactsthatdamsarehavingthroughoutCaliforniaandthroughoutthewest, whenyoudisrupttheflowof a river, therearesomanynegativeconsequencestothesurroundingecosystemthatit's justhardtofititallintoonevideo.
Salmonhaveevolvedtosurviveusingthissamenaturalpatternthatrivershavewiththeirhighflowsinthewinterandthey'relowflowsinthesummertimedamshavebeenconstructedfairlylowdownin a riverandoftenendupblockingtheabilityoffishtomoveupstreamandaccesssomeofthathabitatthattheyneedtoreproduce.
Soiffishladdersandelevatorsandcannonsaren't theanswer, thenwhatis a damnneverlastsforever.
Andsoyouhave a situationwherethereisnolonger a needforthedamandthecostofmaintainingitissohighthatitactuallybeginstomakesensetotakethatdamnoutandtohave a lotoftheecologicalbenefitsthatwouldcomefromdamremoval.
Now, howdoyouremove a damn?
It's notalwaysexplosions.
Eventhoughthatisthemostvisuallyappealing.
Itactuallytakes a lotofwork.
A lotofplanningresearchpermits, surveysandjusttakingitdownin a waythatdoesn't harmtheenvironmentevenmore.
Butitdoeshappen.
It's actuallyhappened a lotintheusalone.
Over 1200 damshavebeenremovedandthathelpsrestoretheriversthattheywereimpacting.