river pronounced central state california mile tributary flowing sierra nevada known swift steep course southern world famous river character changes dramatically reaches foothills slow moving fields activity led sierra river formed steep stream range western flank carrying sediments later help form floor rich zone supported millions migratory birds river southernmost runs salmon north_america indigenous people including tribes lived river thousands years thriving flora fauna supported river diverse lower course aided fertile soils eroded mountains military expeditions history california passed region early 19th century brought people california settled leading establishment railroad river bringing minerals lumber towns established lower later provided tourism national park area conflicts whites indigenous peoples prompted wars resulting expulsion valley 20th century river saw development change state forever large scale agriculture introduced late 19th century led construction numerous state federal privately owned dams water demand higher river environment sustain salmon blocked migrating riverside habitat declined dramatically recent years seen habitat conservation work mimicking historic patterns establishment salmon hopes river health protected damage course feet foot rising confluence cascade polished slopes high country southeastern corner national park flows miles westward series finally flat plains river flows north short distance collects peak fork course turns north west flows steep walled canyon miles river receives collects feet elevation continues northwest miles collects leaving lake river continues west northwest miles open river turns generally westward miles snakes spectacular narrow gorge massive resistant granite cliffs gorge opens river form turning southward unnamed granite cascade little valley glacial valley sits feet feet famous approximately scale river drops receives passes main pine forests fill valley floor join glacial valley end river picks cascade creek turns south near flowing state route follows river west entrance national park miles largest tributary joins left river arcs northwest receive miles enters lake formed new dam river flows west heavily region passing cities joins river hills ferry miles south watershed drainage basin located central spreading square miles km2 characterized slightly smaller southern companion major river north south basin borders watershed includes echo cascade south river miles long largest tributaries south fork include lakes watershed including lake chain lakes lake lake basin characterized alpine climate upper basin river receives heavy snowfall winter usually feed river tributaries year round late autumn reducing flows main stem tributaries significantly causing smaller tributaries dry altogether constitutes majority river early summer flow provides flow happy isles dry season depends supply river flow middle lower basin dominated arid mediterranean semi desert climate river largest tributary irrigation started dams constructed river natural flow mouth higher current average cubic feet second acre feet year upstream river happy isles average flow cubic feet second river locations river happy isles lake mouth record flows unaffected dams human intervention discharge mouth chiefly controlled new dam lake gauge located mining town probably accurate gauge flows overall average annual flow recorded cubic feet second peak cubic feet second reported december mouth gauge highest flow cubic feet second finally gauge happy isles largest flow recorded cubic feet second floods destroyed roads paths bridges valley river primary human use irrigation irrigation district mid operates irrigation infrastructure supplies water acres km2 farmland system includes sets control gates miles canals irrigation taken water lower river rarely reaches sea water return river form irrigation return flows carry mid federally required allow acre feet water annually flow continually river including flooding water allowed river confluence contain water confluence water usually diverted irrigation ecology according study species fish bird species insect species found watershed species divided upper lower watershed usually defined lake formed new dam fish species found lower portion river including sacramento bass bass resident species intentionally introduced humans fish species use lower salmon pacific striped bass upper section river defined stretch lake species fish historically range fish extended head 1950s 1960s years water flowed san rivers allow spawn significant numbers new water use requirements allowed species low salmon mid-20th century high fish 1970s annual run fish seven bird species found occur entire length river birds migratory pass area times year species birds found breeding season despite extensive modifications lower river species birds found lower watershed slow flowing nature river forms marshes zones common species bird basin include crowned cedar american robin yellow tree swallow european endangered species including white tailed hawk birds occur commonly middle upper sections include mourning dove california dark eyed great blue jay red winged red tailed hawk turkey vulture cliff swallow canyon rarely bald eagle insect species include major exotic species chinese crab new_zealand mud species plants found middle upper basin including california poppy white oregon ash oak poison oak maple indian willow historically sugar pine logging began late 19th century bats deer black bear species found middle upper watershed species interest limestone extremely rare habitat downstream limestone depends granite walls canyon survive protect species mile segment canyon covering acres km2 designated area critical environmental concern geology slow journey westwards encountered approximately million years ago began north american continent intense pressure underground caused melt resulting pushed hardened granite makes extensive layers marine rock originally ancient pacific pushed rising granite ancestral formed layer rock millions years cut deep canyon softer rock eventually hitting hard granite beneath encounter rock layer caused river stop tributary streams continued widen ancient canyon million years erosion caused transportation massive amounts sediment floor trapped west sierra nevada east forming incredibly flat fertile land surface present day form upper watershed formed glaciers lower watershed indirectly significantly affected glacial period ice age arrived series tremendous valley glaciers filled upper basin glaciers rose branches upstream descending creek actually eroded deeper arm formed north little valley formed result underlying rock harder cliff wall containing nevada fall branches combined form large feet thick maximum stretching miles downstream past mouth glaciers formed granite cliffs constitute landmarks half dome cloud rest largest eroded upper watershed extent close present form stages followed stages smallest left mouth rocky actually deposited include retreated formed lake flooded nearly entire valley gradual filled lake creating broad flat valley floor sediments glacial origin continued travel following helping form flat floor history native american tribes lived river prominent consisting settled lower sierra lived upper canyon time white explorers came area split permanent villages origin eastern sierra near area lived upper watershed eventually cultural interaction time formed new culture derived meaning valley shaped like big mouth referring shaped early 19th century military expeditions sent spanish colonists coastal california traveled trips headed lieutenant arrived south bank september named river rio river lady mercy patron saint barcelona celebrated september expedition named reaching january feast expedition series ventures funded spanish government find suitable sites missions sierra nevada foothills led expeditions lower canyon time coming eventually plans establish mission chain valley abandoned created named river following establishment independence california mexico settlers came area established small towns dover established confluence dover functioned inland boats delivered supplies area settlers towns followed named set near present day site late 1880s flour mill mill lumber mills constructed operated lumber mills thirty years relying narrow gauge railroads ship lumber sierra nevada river following construction river towns river deserted cities achieve prominence include located railroad 1850s saw gradually increasing mining native americans area revolted leading conflicts miners formed drive remaining valley reservations battalion fought group led river eventually succeeded driving indians reservation near following gold rush allowed incidents prompted second battalion drive time area place names valley origin establishment tourists began travel early roads constructed 1870s road followed big oak flat road trading route environmental movements led convinced establish creation national park tourism valley increased significantly leading roads built upper watershed national forests protecting upper basin followed including originally established discovery mineral deposits canyon continued functioning early 20th century carrying tourists valley constructed canyon end passenger service railway operations continued major flooding occurred destroying sections railroad early 20th century upper basin lay protected lower river subject dam building irrigation irrigation district district proposed dam completed raised 1960s water storage facility irrigation water continued grow substantially land river acres km2 cultivation late 1950s early 1960s irrigation extent rivers ran dry sections confluence river usually dry regaining flow enters mid-20th century flow river diminished degree salmon returned spawn lower section fish built downstream dam fall salmon travel fish ladder pools supplied water diverted valley saw significant amounts damage river flooded valley river modifications despite partial status subject dam building irrigation dams new dam dam dam new dam largest dam river forms lake holds acre feet modern structure preceded old dam forming capacity acre feet old concrete arch dam completed inundated new structure small diversion dams block downstream built irrigation district supply water farms built completely blocks passage fish major lower dam serves regulating dam new dam aside controlling flows lower river dam produces nearly flow river mouth like rivers little water actually reaches pacific_ocean diversion dam timber dam built near flows impact environment damage floods dam originally built generate decommissioned removed 1990s surveyed dam site found dam danger failure classified high hazard structure originally considered inclusion national_register_of_historic_places deemed dangerous today lake completely free flowing dams recreation river tributaries popular recreational area national park activities watershed including boating fishing camping hiking permitted downstream half entrance lake difficult segment rate class iii class upstream boating lake camping upper watershed generally permitted designated river tributaries include ones lake lake ski source railroad flat originates valley railroad travelled old railroad grade exists site public trail trails lead watershed notably starts near happy isles climbs giant staircase past little valley north join near trails follow river little valley area lower river trails segments including lower upper specifically extremely dangerous
Merced River