National Stream Water Quality Accounting Network (NASQAN)

Table 1. NASQAN Stations and approximate sampling frequency during 1996-2000.

Table 2. NASQAN Stations operated in the Mississippi River Basin.
[mi2, square miles; ft3/s, cubic feet per second]

Mississippi River Basin above the Missouri River
Station Number	Station Name	Drainage area (mi2)	Mean Discharge (fr3/s)	Subbasin Defined by Station	Incremental increase in drainage area (mi2)	Inremental increase in mean discahrge (ft3/s)	Upstream NAWQA Study Units	Reasons for selection
05420500	Mississippi R. at Clinton, IA	85,600	48,300	Upper Mississippi	85,600	48,300	1	Characterize flux of materials from upper Mississippi subbasin and Minneapolis-St. Paul NAWQA Study Unit; captures inflow from St. Croix, Chippewa, and Wisconsin Rivers; located above major inflow from corn belt streams; most upstream NASQAN subbasin on Mississippi River.;
05587455	Mississippi R. at Grafton, IL	171,300	130,200	Mid-Mississippi (above Missouri)	87,700	73,900	4	In conjunction with Mississippi River at Thebes will provide verification of flux from mid-Mississippi basin. Most financial support for site is from cooperative program between USGS and the State of Missouri
Missouri River Basin
06329500	Yellowstone River nr Sydney, MT	69,100	12,700	Yellowstone	69,100	12,700	1	NAWQA intergrator site; major tributary to the upper Mo; longest unregulated stream in U.S; noncrop and mining landuse. major input to Lake Sakakawea
06185500	Missouri River near Culbertson, MT	91,600	10,500	Upper Missouri	91,600	10,500	0	characterization of inflow from upstream portion of Missouri River basin; above confluence with Yellowstone River; landuse - range and pasture land; in conjunction with the Yellowstone River will provide essentially all inputs to Lake Sakakawea.
06338490	Missouri River below Garrison Dam, ND	181,400	22,100	Lake Sakaka-wea	20,700	-1,100	1	major reservoir (Lake Sakakawea) below confluence of Missouri and Yellowstone Rivers; will provide means to characterize changes in water chemistry resulting from deposition of sediment, carbon, nutrients, metals etc. from these two basins; characterize inputs to downstream Missouri River system.
06440000	Missouri River at Pierre,SD	243,500	28,600	Lake Oahe	62,100	6,510	1	large increase in drainage area from Lake Sakakawea; below major reservoir (Lake Oahe), a sink for sediment, carbon, metals, and nutrients; input to downstream river system.
6610000	Missouri River at Omaha, NE	322,800	32,200	Mid-Missouri	79,300	3,600	2	large increase in drainage area; below all Missouri River Basin reservoirs which are sinks for sediment and nutrients; above corn belt and major sources of agrichemicals; characterize inputs to lower Missouri subbasin
06805500	Platte River at Louisville, NE	85,800	6,800	Platte	85,800	6,800	3	tributary;integrator site for 3 NAWQA units; basin for Miss. Carbon study; first major agrichemical input to Missouri River
06934500	Missouri River at Hermann, MO	524,200	84,500	Lower Missouri	115,600	45,500	6	terminus of Missouri River; dominates sediment input to Mississippi River; more than 40% of drainage area of Mississippi basin
Mississippi River Basin below Missouri River
07022000	Mississippi River at Thebes, IL	713,200	203,400	Mid-Mississippi	15,100	17,700	10	integrator site for all Mississippi River flow above the Ohio River including the Missouri River basin; compare sum of Hermann and Grafton flux with Thebes to assess accuracy. Values not used to determine incremental contribution of this subbasin.
Ohio River Basin
03216600	Ohio River at Greenup, KY	62,000	89,400	Upper Ohio	62,000	89,400	2	upstream coal mining and industry; below 2 NAWQA study units; most upstream NASQAN site on the Ohio R; input to mid-Ohio subbasin
03303280	Ohio River at Cannelton Dam, KY	97,000	125,700	Mid-Ohio	35,000	36,300	4	large increase in flow; integrator site for 2 intervening NAWQA units between Greenup site and this site; characterize output from mid-Ohio subbasin.
03377500	Wabash at Mt. Carmel, IL	28,600	27,700	Wabash	28,600	27,700	1	major tributary; poor quality water with high agrichemical input to Ohio River; integrator site for NAWQA unit.
03609750	Tennessee River at Paducah, KY	40,300	68,400	Tennessee	40,300	68,400	2	major tributary to Ohio River; good quality water; integrator site for 2 NAWQA Units.
03612500	Ohio River at Grand Chain, IL	203,000	270,900	Lower Ohio	37,100	49,100	7	terminus of Ohio River; provides approximately 50% of water inflow to Mississippi; subbasin contribution calculated as difference between outflow and inflow from Wabash, Tennessee, and mid-Ohio
Lower Mississippi River
07263620	Arkansas River at D. Terry Dam, below Little Rock, AR	158,300	48,400	Arkansas	158,300	48,400	~1.5	major tributary; integrator site for 2 NAWQA units; largest input to Mississippi R. below Ohio River.
07381495	Atchafalaya River at Melville, LA	93,300 + Mississippi diversion	234,700 (includes Mississippi diversion	Red/Ouachita	93,300	varies with Mississppi diversion	~1.5	distributary of Mississippi River; receives about 25% of Mississippi flow, as well as inflow from the Red and Ouachita Rivers; in conjunction with St. Francisville, provides total flux from Mississippi basin to Gulf of Mexico; subbasin contribution calculated as difference between outflow and diversion from Mississippi R.
07373420	Mississippi River at St Francisville, LA	1,125,300	514,500	Lower Mississippi	50,800	varies with Mississippi diversion	21.5	terminus of Mississippi River; upstream of Baton Rouge and New Orleans; in conjunction with the Atchafalaya River will provide total flux from Mississippi basin to Gulf of Mexico; subbasin contribution calculated as difference between outflow (measurements at St. Francisville plus diversion to Atchafalaya R.) and inflows from Ohio RIver, Mississippi R. at Thebes, and Arkansas R.
	Total including Mississippi and Atchafalaya Rivers	1,218,600	749,200		--	--	23

Table 3. NASQAN Stations operated in the Rio Grande Basin

Table 4. NASQAN Stations operated in the Columbia River Basin.
[cfs, cubic feet per second]

Table 5. NASQAN Stations operated in the Colorado River Basin.
[mi2, square miles; ft3/s, cubic feet per second]