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Report Site Map > Monitoring Network for Nine Major Subbasins Comprising the Mississippi-Atchafalaya River Basin

USGS Open-File Report 2007-1080 - Streamflow and Nutrient Fluxes of the Mississippi-Atchafalaya River Basin and Subbasins for the Period of Record Through 2005

Monitoring Network for Nine Major Subbasins Comprising the Mississippi-Atchafalaya River Basin

In addition to the stations that are used to estimate delivery to the Gulf of Mexico, monitoring for flow and nutrient flux is conducted at 9 locations that are either on the main stem of the Mississippi River or are located on the major subbasins. Data from 16 stations are used to calculate flow and nutrient fluxes for major subbasins of the Mississippi-Atchafalaya River Basin at these 9 locations. The station locations are shown in figures 1 and 2 and pertinent station information is provided in table 1.

The sampling station below Alton, Illinois, was relocated to below Grafton, Illinois, in 1989 after concurrent monitoring demonstrated that data from these stations were comparable. Flow data for these two stations were collected from stations adjacent to the water-quality sampling stations. Water-quality data for these two stations were combined in this analysis to yield a single long-term dataset. Nutrient flux estimates at the mouth of the Ohio River use flow data measured at Metropolis, Illinois, and water-quality data collected at Grand Chain, Illinois. Nutrient flux estimates for the Arkansas River use flow data measured near Little Rock, Arkansas, and water-quality data collected below Little Rock, Arkansas. For all other stations, flow and water-quality information is collected at the same station.

Sampling is active for all nine major subbasins as of 2006. Seven of the nine subbasins are currently part of the National Stream Quality Accounting Network (NASQAN) Program network. The Red River at Alexandria, Louisiana, and the stations on the Mississippi River at and below Grafton, Illinois, are supported by other U.S. Geological Survey activities.

  
Figure 1. Schematic of Mississippi-Atchafalaya River Basin showing additional sampling stations used for estimating nutrient fluxes for the major subbasins
Figure 1. Schematic of Mississippi-Atchafalaya River Basin showing additional sampling stations used for estimating nutrient fluxes for the major subbasins.

Figure 2. Location of nine large subbasins comprising the Mississippi-Atchafalaya River Basin that are used for estimating and studying nutrient fluxes.
Figure 2. Location of nine large subbasins comprising the Mississippi-Atchafalaya River Basin that are used for estimating and studying nutrient fluxes. (Subbasin number is identified in table 1.)
   
Table 1. Summary of information for stations used for nutrient flux estimation for the major Mississippi-Atchafalaya River Basin subbasins. [The Map No. column refers to the subbasins identified in figure 2.]
Station Name   Station ID    Drainage Area 
(km2) 		Map No. Data Type Source
Mississippi River at Clinton, Iowa 05420500 222,000    1 flow and quality USGS
Mississippi River below Grafton, Ill.1,2,3 05587455 443,700    2 quality USGS
    Mississippi River at Grafton, Ill. 05587450 443,700    2 flow USGS
Mississippi River below Alton, Ill.1,2,3 05587550 444,200    2 quality USGS
    Mississippi River at Alton, Ill. 05587500 444,200    2 flow USGS
Missouri River at Omaha, Nebr. 06610000 836,000    3 flow and quality USGS
Missouri River at Hermann, Mo.4 06934500 1,353,000    4 flow and quality USGS
Mississippi River at Thebes, Ill.5 07022000 1,847,000    5 flow and quality USGS
Ohio River at Cannelton Dam at Cannelton, Ind. 03303280 251,000    6 flow and quality USGS
Ohio River at Dam 53 near Grand Chain, Ill.1,6 03612500 526,000    7 quality USGS
    Ohio River at Metropolis, Ill. 03611500 525,800    7 flow USGS
Arkansas River below Little Rock, Ark.1 07263620 409,964    8 quality USGS
    Arkansas River near Little Rock, Ark. 07263450 409,300    8 flow USGS
Red River at Alexandria, La.7 07355500 175,000    9 Flow and quality USGS and USACE
    Atchafalaya River at Simmesport, La. 03045 226,800    9 flow USACE
    Old River Outflow Channel near Knox Landing, La. (Total Outflow) 02600 --       9 flow USACE
1   =   Flow measurements are used from nearby stations, which are identified in the next row.
2   =   The sampling station below Alton, Ill., was relocated to below Grafton, Ill., in 1989.
3   =   Subbasin includes one upstream subbasin (Map Number 1).
4   =   Subbasin includes one upstream subbasin (Map Number 3).
5   =   Subbasin includes four upstream subbasins (Map Numbers 1 through 4).
6   =   Subbasin includes one upstream subbasin (Map Number 6).
7   =   Flow data augmented by measurements at the stations identified in the next two rows. Additional flow data details are available.
USGS   =   United States Geological Survey
USACE   =   United States Army Corps of Engineers

Report Site Map > Monitoring Network for Nine Major Subbasins Comprising the Mississippi-Atchafalaya River Basin

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