Editing Sacramento River (section)

===Discharge===
Following the [[Columbia River]], the Sacramento is the largest river by [[Discharge (hydrology)|discharge]] on the Pacific coast of the continental United States. The natural runoff of the river is {{convert|22|e6acre.ft|km3}} per year, or about {{convert|30000|cuft/s|m3/s}}. Before dams were built on its tributaries, the river flooded up to {{convert|650000|cuft/s|m3/s}} during the rainy season, equal to the flow of the [[Mississippi River]]. Late summers of particularly dry years could see flows drop below {{convert|1000|cuft/s|m3/s}}.<ref>{{cite web|last=Ellis|first=Tom|url=http://www.familywateralliance.com/flood_ellisflows.html|title=How Much Water Flows Through The Sacramento River During a Flood Event?|publisher=Family Water Alliance|access-date=August 27, 2010|url-status=dead|archive-url=https://web.archive.org/web/20100605040030/http://www.familywateralliance.com/flood_ellisflows.html|archive-date=June 5, 2010}}</ref><ref name="NAWQA">{{cite web
 |url          = http://ca.water.usgs.gov/sac_nawqa/study_description.html
 |title        = Study Unit Description
 |publisher    = U.S. Geological Survey
 |work         = Sacramento River Basin NAWQA Program
 |access-date  = August 28, 2010
 |url-status   = dead
 |archive-url  = https://web.archive.org/web/20090813040059/http://ca.water.usgs.gov/sac_nawqa/study_description.html
 |archive-date = August 13, 2009
}}</ref> Large volumes of water are withdrawn from the Sacramento River for irrigation, industry and urban supplies. Annual depletions (water not returned to the river after use) are about {{convert|4.72|e6acre.ft|km3}} for irrigation and {{convert|491000|acre feet|km3}} for urban use. An additional {{convert|7.61|e6acre.ft|km3}} is reserved for environmental uses, primarily to maintain a minimum fresh water outflow in the Delta to combat salinity.<ref>{{cite web |url=http://www.norcalwater.org/2014/03/24/understanding-water-use-in-california-and-the-sacramento-valley/ |title=Understanding Water Use in California and the Sacramento Valley &#124; Northern California Water Association |access-date=March 11, 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160311140839/http://www.norcalwater.org/2014/03/24/understanding-water-use-in-california-and-the-sacramento-valley/ |archive-date=March 11, 2016 }}</ref>

[[Image:VIEW TO SOUTHEAST. AERIAL VIEW OF AREA DURING FLOOD STAGE. GIANELLA BRIDGE AT UPPER RIGHT Photographer unknown, January 24, 1970 - Gianella Bridge, Spanning Sacramento River HAER CAL,11-HAMCI.V,1-33.tif|thumb|right|Flooding on the Sacramento River, January 24, 1970]]
The [[U.S. Geological Survey]] (USGS) has [[stream gauge]]s on 25 locations along the Sacramento River, although not all of them are currently operational.<ref>{{cite web
 |url          = http://waterdata.usgs.gov/nwis/annual?referred_module=sw&search_station_nm=sacramento%20river&search_station_nm_match_type=beginning&state_cd=ca&format=station_list&sort_key=site_no&group_key=NONE&list_of_search_criteria=state_cd,search_station_nm,realtime_parameter_selection
 |title        = USGS Surface-Water Annual Statistics Search Keyword "Sacramento River"
 |publisher    = U.S. Geological Survey
 |work         = Water Resources of the United States
 |access-date  = September 20, 2010
 |url-status   = dead
 |archive-url  = https://web.archive.org/web/20160303174148/http://waterdata.usgs.gov/nwis/annual?referred_module=sw&search_station_nm=sacramento%20river&search_station_nm_match_type=beginning&state_cd=ca&format=station_list&sort_key=site_no&group_key=NONE&list_of_search_criteria=state_cd,search_station_nm,realtime_parameter_selection
 |archive-date = March 3, 2016
}}</ref> The ones currently in operation are at Delta, California (near the source at Mount Shasta), at [[Keswick, California|Keswick]] (near Redding), [[Colusa, California|Colusa]] (about halfway down the river), [[Verona, California|Verona]], and [[Freeport, California|Freeport]]. The Freeport gauge, which sits just downstream of Sacramento, provides a relatively good metric of the annual outflow from the Sacramento River Basin. The average flow between 1949 and 2013 was {{convert|23330|cuft/s|m3/s}}. The maximum recorded flow was {{convert|115000|cuft/s|m3/s}} on February 19, 1986; the lowest was {{convert|3970|cuft/s|m3/s}} on October 15, 1977.<ref name="Freeport-discharge">{{cite web
 |url          = http://wdr.water.usgs.gov/wy2013/pdfs/11447650.2013.pdf
 |title        = USGS Gage #11447650 on the Sacramento River at Freeport, CA (Water-Data Report 2013)
 |publisher    = U.S. Geological Survey
 |work         = Water Resources of the United States
 |access-date  = February 19, 2016
 |url-status   = dead
 |archive-url  = https://web.archive.org/web/20160311134238/http://wdr.water.usgs.gov/wy2013/pdfs/11447650.2013.pdf
 |archive-date = March 11, 2016
}}</ref> Flow in the [[Yolo Bypass]], a relief channel designed to carry a portion of the flood waters in order to protect the Sacramento area, is not measured by the Freeport gauge. A separate gauge on the bypass recorded an average throughput of {{convert|4809|cuft/s|m3/s}} between 1939 and 2013, mostly from December–March. The highest recorded flow was {{convert|374000|cuft/s|m3/s}} on February 20, 1986. During the dry season of July through September, the bypass carries low to zero flow.<ref name="Yolo-bypass-discharge">{{cite web
 |url        = http://wdr.water.usgs.gov/wy2013/pdfs/11453000.2013.pd
 |title      = USGS Gage #11453000 on Yolo Bypass near Woodland, CA (Water-Data Report 2013)
 |publisher  = U.S. Geological Survey
 |work       = Water Resources of the United States
 |format     = PDF
 |access-date = February 19, 2016
}}{{dead link|date=May 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name="coursechanges">{{cite web|author1=Buer, Koll|author2=Forwalter, Dave|author3=Kissel, Mike|author4=Stohler, Bill|url=http://www.fs.fed.us/psw/publications/documents/psw_gtr110/psw_gtr110_a_buer.pdf|title=The Middle Sacramento River: Human Impacts on Physical and Ecological Processes along a Meandering River|publisher=US Forest Service|work=Pacific Southwest Research Station|access-date=August 27, 2010|url-status=live|archive-url=https://web.archive.org/web/20111026165710/http://www.fs.fed.us/psw/publications/documents/psw_gtr110/psw_gtr110_a_buer.pdf|archive-date=October 26, 2011}}</ref>

Although the Sacramento River nominally begins near Mount Shasta, the true hydrological source of the Sacramento River system is the Pit River, which is by far the largest of the three rivers flowing into Shasta Lake. At the USGS Montgomery Creek gauge, the average flow of the Pit River was {{convert|4760|cuft/s|m3/s|abbr=on}} for the period 1966–2013.<ref name="Pit-discharge">{{cite web
 |url          = http://wdr.water.usgs.gov/wy2013/pdfs/11365000.2013.pdf
 |title        = USGS Gage #11365000 on the Pit River near Montgomery Creek, CA: Water-Data Report 2013
 |publisher    = U.S. Geological Survey
 |work         = National Water Information System
 |date         = 1945–2013
 |access-date  = February 19, 2016
 |url-status   = dead
 |archive-url  = https://web.archive.org/web/20160311134206/http://wdr.water.usgs.gov/wy2013/pdfs/11365000.2013.pdf
 |archive-date = March 11, 2016
}}</ref> By comparison, the Sacramento River at Delta gauge, a few miles above Shasta Lake, recorded an average of {{convert|1191|cuft/s|m3/s|abbr=on}} for the period 1945–2013.<ref name="Deltadis">{{cite web
 |url          = http://wdr.water.usgs.gov/wy2013/pdfs/11342000.2013.pdf
 |title        = USGS Gage #11342000 on the Sacramento River at Delta, CA: Water-Data Report 2013
 |publisher    = U.S. Geological Survey
 |work         = National Water Information System
 |date         = 1945–2013
 |access-date  = February 19, 2016
 |url-status   = dead
 |archive-url  = https://web.archive.org/web/20160311133651/http://wdr.water.usgs.gov/wy2013/pdfs/11342000.2013.pdf
 |archive-date = March 11, 2016
}}</ref> The McCloud River had an average discharge of {{convert|775|cuft/s|m3/s|abbr=on}} for the 1967–2013 period.<ref name="McCloud-discharge">{{cite web
 |url          = http://wdr.water.usgs.gov/wy2013/pdfs/11368000.2013.pdf
 |title        = USGS Gage #11368000 on the McCloud River above Shasta Lake, CA: Water-Data Report 2013
 |publisher    = U.S. Geological Survey
 |work         = National Water Information System
 |date         = 1946–2013
 |access-date  = February 19, 2016
 |url-status   = dead
 |archive-url  = https://web.archive.org/web/20160311132133/http://wdr.water.usgs.gov/wy2013/pdfs/11368000.2013.pdf
 |archive-date = March 11, 2016
}}</ref> Since the 1960s, the McCloud River flow has been reduced and the Pit River flow increased due to diversion of water for hydropower generation; however the total volume of water entering Shasta Lake remains the same.<ref name="Pit-discharge"/><ref name="McCloud-discharge"/> Before Shasta Dam was built, the volcanic springs feeding the Pit and McCloud Rivers provided the majority of river flow in dry summers when the Upper Sacramento and other tributaries slowed to a trickle.<ref name="PitRiverWatershed"/>

<div class="center">
'''Monthly combined discharge of Sacramento River at [[Freeport, California|Freeport]] and Yolo Bypass near [[Woodland, California|Woodland]] (cfs)'''<ref>{{cite web|url=http://nwis.waterdata.usgs.gov/nwis/monthly/?referred_module=sw&amp;site_no=11447650&amp;por_11447650_2=2209860,00060,2,1948-10,2014-09&amp;format=html_table&amp;date_format=YYYY-MM-DD&amp;rdb_compression=file&amp;submitted_form=parameter_selection_list|title=USGS Gage #11447650 on the Sacramento River at Freeport, CA, Monthly Data 1948-2014|publisher=U.S. Geological Survey|work=National Water Information System|access-date=February 19, 2016|url-status=dead|archive-url=https://web.archive.org/web/20170524225128/https://nwis.waterdata.usgs.gov/nwis/monthly/?referred_module=sw&site_no=11447650&por_11447650_2=2209860,00060,2,1948-10,2014-09&format=html_table&date_format=YYYY-MM-DD&rdb_compression=file&submitted_form=parameter_selection_list|archive-date=May 24, 2017}}</ref><ref>{{cite web|url=http://nwis.waterdata.usgs.gov/nwis/monthly/?referred_module=sw&amp;site_no=11453000&amp;por_11453000_2=2209900,00060,2,1939-10,2013-01&amp;format=html_table&amp;date_format=YYYY-MM-DD&amp;rdb_compression=file&amp;submitted_form=parameter_selection_list|title=USGS Gage #11453000 on Yolo Bypass near Woodland, CA, Monthly Data 1945-2011|publisher=U.S. Geological Survey|work=National Water Information System|access-date=October 9, 2010|url-status=dead|archive-url=https://web.archive.org/web/20170524225141/https://nwis.waterdata.usgs.gov/nwis/monthly/?referred_module=sw&site_no=11453000&por_11453000_2=2209900,00060,2,1939-10,2013-01&format=html_table&date_format=YYYY-MM-DD&rdb_compression=file&submitted_form=parameter_selection_list|archive-date=May 24, 2017}}</ref>
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