NASQAN National Stream Quality Accounting Network
The first objective for NASQAN is to address questions about the annual transport of selected constituents from selected large rivers to coastal waters of the United States. These questions include:
A. What are the concentrations and loads of nitrogen, phosphorus, carbon, silica, dissolved solids, selected pesticides, and suspended sediment discharging to coastal waters of the United States?
B. How do concentrations and loads of these constituents change through time?
The second objective for NASQAN is to address questions specific to the Mississippi-Atchafalaya River Basin (MARB) related to hypoxia in the Gulf of Mexico. These questions include (in addition to questions A and B listed under the first objective):
A. What are the seasonal loads of total and dissolved nutrients from the Mississippi River Basin to the Gulf of Mexico?
B. What are the concentrations and loads of objective 1 constituents in major subbasins and selected smaller basins within the Mississippi River Basin?
C. How do concentrations and loads of objective 1 constituents change through time in major subbasins and selected smaller basins within the Mississippi River Basin?
Thirteen large rivers are included in the NASQAN Coastal Subnetwork. The 13 coastal rivers are the Altamaha River, Atchafalaya River, Colorado River, Columbia River, Mississippi River, Mobile River, Potomac River, Rio Grande, Sacramento River, San Joaquin River, St. Lawrence River, Susquehanna River, and Yukon River. Together, the 12 stations on rivers in the conterminous United States contribute approximately 80 percent of the total discharge of streamflow, nitrogen, phosphorus, and suspended sediment to coastal waters from this part of the United States.
Twenty stations are included in the NASQAN MARB Subnetwork. These stations include two on the Ohio River, three tributaries to the Ohio, two stations on the Missouri River, one tributary to the Missouri River, five stations on the Mississippi River, five stations on rivers tributary to the Mississippi River (excluding the Missouri and Ohio), and two stations on the Atchafalaya River.
In addition to the 33 stations operated by the NASQAN program, 5 stations with the same objectives are operated as part of the Ocean Action Plan National Monitoring Network (NMN Subnetwork). Of the 5 stations in the NMN Subnetwork, 4 are coastal rivers (Hudson, Delaware, Apalachicola, and Brazos) and one is on the Mississippi River. Information about these sites is also included on the NASQAN web site.