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Environmental Setting
<br /> SACRAMENTO-SAN JOAQUIN DELTA AND SAN JOAQUIN RIVER BASIN
<br /> The Delta forms the lowest part of the Central Valley,lying between the Sacramento and San s f
<br /> Joaquin rivers and extending inland from the confluence of the two rivers to Sacramento and 1
<br /> Stockton. The Delta is roughly bordered by the cities of Sacramento,Stockton,Tracy,and 12 0�°°°
<br /> Pittsburg. Other cities within the Delta include Manteca,Lathrop,Antioch,Brentwood,Rio n
<br /> Vista,and Isleton. There are also about 14-unincorporated towns and communities in the Delta. A ° u
<br /> The area receives runoff from over 45 percent of the State's land area including flows from 19 t
<br /> tributaries:the Sacramento,McCloud,Butte,Feather,Yuba,Bear,American,Merced,San t �a
<br /> Joaquin,Mokelumne,Cosumnes,Stanislaus,Tuolumne,Chowchilla,Fresno,Kings,Cache, o
<br /> Putah,and Calaveras rivers. The Delta is within the jurisdiction of six counties(Alameda, S
<br /> Contra Costa,Sacramento,San Joaquin,Solano,and Yolo)and covers approximately 1,500 o J
<br /> square miles interlaced with hundreds of miles of waterways(DWR,1993). The Delta is K a
<br /> delineated by a legal boundary that includes the areas that historically were intertidal,along with t
<br /> supratidal portions of the floodplains of the Sacramento and San Joaquin rivers. Today's legal z+
<br /> Delta extends between the upper extent of tidal effect(near the City of Sacramento on the } .9 a 1�
<br /> Sacramento River and Vernalis on the San Joaquin River)and Chipps Island on the west r'
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<br /> (CALFED,1999).
<br /> The 290-mile-long San Joaquin Valley occupies the southern half of the Central Valley and has
<br /> an average width of 130 miles. It covers approximately 32,000 square miles,or one-fifth of the z
<br /> surface area of California. The San Joaquin River Basin is bounded on the west by the Coast €► r 1
<br /> Ranges and on the east by the Sierra Nevada mountain range. The Tulare Lake Basin to the _
<br /> south is normally considered a separate drainage basin,but has contributed occasional flood : I"
<br /> flows and subsurface flows to the San Joaquin River during wet years(DWR,1995). The San s °` ,g
<br /> Joaquin River itself is 330 miles in length and drains a watershed area of 13,540 square miles
<br /> (CSLC,1993). It flows west from the Sierra Nevada,turns sharply north at the center of the - ! o
<br /> valley floor,and flows north through the valley into the Delta. San Joaquin River monthly
<br /> average flow ranges from 400 to 1,500 cubic feet per second(cfs)in dry years,1,500 to 3,500 cfs
<br /> in normal years,and up to 20,000 cfs to 40,000 cfs in wet years(CALFED,1999). Major
<br /> tributaries draining the Sierra Nevada and flowing into the San Joaquin River include the =
<br /> Stanislaus,Tuolumne,Merced,and Fresno rivers(see Figure 1). The San Joaquin River flows • .
<br /> through portions of Fresno,Madera,Merced,Stanislaus,San Joaquin,Contra Costa,and a
<br /> Sacramento counties. The WQCF is currently permitted to discharge secondary treated effluent
<br /> to the San Joaquin River approximately one mile upstream of the Mossdale Bridge which is
<br /> located near the intersection of Interstate 5 and Highway 120. %
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<br /> ,•� rd Z• /: 1 V S w w C
<br /> Figure 1: Lower San Joaquin River and Eastside Tributaries
<br /> City of Manteca Antidegradation Analysis 15 June 2007 City of Manteca Antidegradation Analysis 16 June'007
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