Water quality in the St Croix National Scenic Riverway, Wisconsin

Water-Resources Investigations Report 85-4319




A water quality study of the St. Croix National Scenic Riverway, was conducted during the period 1975-83. The water was shown to be good for most uses and is a calcium bicarbonate type. Concentrations of most constituents analyzed, and constituent loads and yields were lower in the Scenic Riverway than in other Wisconsin streams. Water quality samples were collected at 10 stations throughout the study area and were compared to analyses of samples from selected National Stream Quality Accounting Network stations (NASQAN) and the Hydrologic Bench-Mark Network (HBMN) station in Wisconsin. The average suspended sediment (SS) concentration for 9 of the 10 stations in this study was 7.7 mg/L. This compared with an average SS concentration of 11 mg/L for two other stations in the scenic riverway and an average SS concentration of 110 mg/L for Wisconsin. The concentrations of major cations and anions at two of the stations were similar to concentrations at the HBMN station Popple River near Fence. Mean total phosphorus concentrations ranged from 0.02 to 0.08 mg/L at the study stations and from 0.03 to 0.16 mg/L at selected NASQAN stations. Concentrations of trace metals were below safe drinking water standards at all the study sites, except for iron and manganese which exceeded drinking water standards at some of the study sites. Pesticides were sampled at the St. Croix River at St. Croix Falls and above and below cranberry bogs that drain into the Namekagon River. No pesticides were detected in the water/suspended sediment mixture or bottom material. Average annual loads of SS, total phosphorus, total nitrogen, and dissolved solids were calculated by a flow duration curve method. Annual SS loads ranged from 580 to 25,000 tons/yr at the study stations. Annual SS loads at the HBMN station and NASQAN stations ranged from 720 tons at the Popple River near Fence to 443,000 tons at the Chippewa River near Durand. Average annual total phosphorus loads ranged from 6,800 to 900,000 pounds at the study stations compared with 145,000 to 1,600,000 pounds at selected Wisconsin NASQAN stations. Suspended sediment yields ranged from 1.9 to 13.3 tons/sq mi. The average SS yield for Wisconsin is 80 tons/sq mi. Total phosphorus and other constituents exhibited the same trend. (Lantz-PTT)

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USGS Numbered Series
Water quality in the St Croix National Scenic Riverway, Wisconsin
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Water-Resources Investigations Report
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United States Department of the Interior, Geological Survey,
iv, 48 p. :ill., maps ;28 cm.