A set of daily streamflow-routing models are used to simulate Streamflow at 10 sites along the Wisconsin River for water years 1915-76, to determine the effects the reservoir system has on flood discharges. Streamflow is simulated under the following two conditions: (1) No reservoirs are in the system and (2) all of the present reservoirs are in place and operated with current rules. At Wisconsin Dells, 20 miles upstream from Portage, daily Streamflow hydrographs are estimated for the 10-, 50-, 100-, and 500-year floods. These were determined from statistical analysis of the simulated daily streamflows for the condition of all reservoirs in place. The reservoirs have a significant impact on floods. The mean annual flood peak at Wisconsin Dells is lowered about 20 percent from 43,000 cubic feet per second for the simulated, unregulated condition to 34,000 cubic feet per second for the simulated, regulated condition. The 100-year flood peak at Wisconsin Dells is reduced about 10 percent (92,000 to 82,000 cubic feet per second) between the simulated, unregulated and simulated, regulated conditions. The 100-year flood peak at Wisconsin Dells, computed from the simulated, regulated Streamflow data for the period 1915-76, is 82,000 cubic feet per second, including the effects of all the reservoirs in the river system, as they are currently operated. It also includes the effects of Lakes Du Bay, Petenwell, and Castle Rock which are significant for spring floods but are insignificant for summer or fall floods because they are normally maintained nearly full in the summer and fall and have very little storage for floodwaters. L. L. Sheerar of WVIC and M. 0. Andrae of Wisconsin River Power Co. gave advice and instruction on operation of the reservoir system and hydroelectric dams which was necessary for the modeling. M. J. Mezzo and T. L. Hampton of the Wisconsin Department of Natural Resources obtained the reservoir stage records from WVIC and CWPC, computed daily changes in storage, and provided these data on magnetic tape for computer processing. The U.S. Army Corps of Engineers gave advice and assistance in the statistical analysis of the simulated streamflow records and in computation of flood hydrographs for Wisconsin Dells. DATA BASE Data used in digital modeling consisted of (1) daily streamflow data from 18 U.S. Geological Survey gaging stations, (2) reservoir stage data from WVIC, and (3) stage data from hydroelectric pools from CWPC. Locations of the U.S. Geological Survey gaging stations used in this report are shown on plate 1. Their full names, periods of record, and drainage areas are summarized in table 1. For simplicity all gaging stations on the Wisconsin River will be referred to by the location, for example, the Wisconsin River at Rainbow Lake near Lake Tomahawk will be referred to as Rainbow Lake. Gages on tributary streams will be referred to simply by the name of the river, unless more detail is required to avoid confusion. Locations of these gaging stations are also shown in a schematic diagram in f...

A reconnaissance study was conducted of 22 streams tributary to Green Bay to determine whether any of the streams contribute toxic substances to the bay. This effort was part of a comprehensive investigation of Green Bay funded by the U.S. Environmental Protection Agency, Great Lakes National Program Office. The U.S. Geological Survey sampled the bottom sediments and water columns of 11 streams tributary to western Green Bay for polychlorinated biphenyls, lead, and cadmium. Four of these streams also were sampled for dieldrin, a pesticide previously used in the watershed. An additional 11 streams tributary to eastern Green Bay were sampled for dieldrin in the bottom sediment and storm runoff. Samples were collected from July 1987 through April 1988. Neither dieldrin nor cadmium was detected in any of the sampled tributaries. Detectable concentrations of polychlorinated biphenyls and lead were found at only three sites. Polychorinated biphenyls (0.10 microgram per gram) and lead (10 milligrams per kilogram) were found in the bottom sediment of Duck Creek, a western-shore tributary near the city of Green Bay. Lead (10 milligrams per kilogram) also was found in the bottom sediment of the Suamico River near the mouth, about 5 miles north of Duck Creek. Lead (4 micrograms per liter) was detected in a spring-runoff sample from the Fishdam River, a tributary from upper Michigan.

Polychlorinated biphenyls (PCB's) in the bottom sediment and water column of Little Lake Butte des Morts were studied by the Wisconsin Department of Natural Resources and the U.S. Geological Survey. The lake is a 8-kilometer-long impoundment of the Fox River between Lake Winnebago and Appleton, Wisconsin. Discharge of PCB's into the lake by paper mills and waste-treatment plants has resulted in their accumulation in the bottom sediment. The accumulation of PCB's in the sediment was estimated to be 1,100 kilograms in October 1987. The concentrations of PCB's in bottom-sediment core samples were as much as 190 micrograms per gram dry sediment. The congener distribution of the PCB's present in the lake most closely resembles that for the Aroclor 1242 PCB's mixture.

The U.S. Geological Survey collected water samples from the five major tributaries to Green Bay, Lake Michigan, to determine the load of total polychlorinated biphenyls (RGB's) entering the bay. These samples were collected from January 1989 through early May 1990 from the Escanaba, Menominee, Peshtigo, Oconto, and Fox Rivers. Sampling sites were located near the mouth of each river and also just upstream of De Pere dam on the Fox River. Water samples were collected for analysis of total, dissolved, and particulate concentrations of PCB's at the nanogram-per-liter level. Loads of PCB's entering Green Bay were computed using a total-integration method. The methods used to collect water samples and compute the loads of total PCB's entering the bay are described in this report. Graphs showing total PCB's concentrations and loads are presented for each site, along with the corresponding data tables. These data indicate that the amount of total PCB's entering the bay from the Fox River is greater than from all other major tributaries combined.

Plate 1. Drainage basin and base-flow measurement sites of Bridge Creek, Wis.