Limnological Monitoring on the Upper Mississippi River System, 1993-1996: Long Term Resource Monitoring Program Onalaska Field Station
Abstract
Since 1988 the Long Term Resource Monitoring Program (LTRMP) staff have performed basic limnological field measurements in the Upper Mississippi River System. The period of this report (1993-96) includes a major revision of the LTRMP sampling design in 1993 that added randomization broader spatial coverage and increased monitoring of tributaries and locations that allow monitoring of material transport. Personnel from the LTRMP Onalaska (Wisconsin) Field Station made about 1300 vi sits to fixed limnological sampling sites and 2100 visits to stratified random sites in the vicinity of Navigation Pool 8 from 1993 through 1996. An extended late-season flood in summer 1993 coincided with some of the highest nutrient and lowest dissolved oxygen (DO) concentrations recorded during the report period. Decreases in nutrient concentrations (particularly nitrogen) and increases in water clarity occurred over the 4-year period. Midday DO concentrations were above 5 mg/L throughout most of the year and across most of Pool 8 with localized exceptions during periods of snow cover. Pool 8 and its watershed are a net source of sediment to the Mississippi River main channel suspended solids concentrations were greater downstream than upstream and concentrations in the tributaries were typically higher than in the main channel. Strong seasonal patterns were evident for temperature DO Secchi transparency turbidity total and volatile suspended solids silicate chlorophyll-alpha and total phosphorus. Spatial variability (among strata) of most measurements generally increased during lower discharge. Within the individual strata, the pattern of variability could be generalized as follows: isolated backwater greater than contiguous backwater greater than impounded greater than or equal to side channel greater than or equal to main channel.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2002
- Accession Number
- ADA408414
Entities
People
- David M. Soballe
- James R. Fischer
- Lisa A. Hodge-richardson
- Troy L. Clemment