Characteristics of water, sediment, and benthic communities of the Wolf River, Menominee Indian Reservation, Wisconsin, water years 1986-98

Analyses and interpretation of water quality, sediment, and biological data from water years 1986 through 1998 indicated that land use and other human activities have had only minimal effects on water quality in the Wolf River upstream from and within the Menominee Indian Reservation in northeastern Wisconsin. Relatively high concentrations of calcium and magnesium (natural hardness), iron, manganese, and aluminum were measured in Wolf River water samples during water years 1986-98 from the three sampled sites and attributed to presence of highly mineralized geologic materials in the basin. Average calcium and magnesium concentrations varied from 22-26 milligrams per liter (mg/L) and 11-13 mg/L, respectively. Average iron concentrations ranged from 290-380 micrograms per liter (μg/L); average manganese concentrations ranged from 53-56 mg/L. Average aluminum concentrations ranged from 63-67 μg/L. Mercury was present in water samples but concentrations were not at levels of concern. Levels of Kjeldahl nitrogen, ammonia, nitrite plus nitrate, total phosphorus, and orthophosphorus in water samples were often low or below detection limits (0.01- 0.10 mg/L). Trace amounts of atrazine (maximum concentration of 0.031 μg/L), deethylatrazine (maximum 0.032 μg/L), and alachlor (maximum of 0.002 μg/L) were detected. Low concentrations of most trace elements were found in streambed sediment.

Tissues of fish and aquatic invertebrates collected once each year from 1995 through 1998 at the Langlade and Keshena sites, near the northern and southern boundaries of the Reservation, respectively, were low in concentrations of most trace elements. Arsenic and silver in fish livers from both sites were less than or equal to 2 μg/g arsenic and less than 1 μg/g silver for dry weight analysis, and concentrations of antimony, beryllium, cadmium, cobalt, lead, nickel, and uranium were all below detection limits (less than 1 μg/g dry weight). Concentrations of most other trace elements in fish were low, with the exceptions of chromium, copper, mercury, and selenium; however, these concentrations are not at levels of concern. Concentrations of all trace elements analyzed in whole caddisfly larvae also were low compared to those reported in the literature.

During 1998, a total of 48 species of macroinvertebrates were identified at each of two sampled sites, with similar numbers of genera represented at both: 41 at Keshena and 44 at Langlade. The percentage EPT (Ephemeroptera, Plecoptera, and Trichoptera) was 52 at Keshena and 77 at Langlade; these relatively large percentages suggest very good to excellent water quality at these sites. A total of 52 algal taxa were identified at the Wolf River near Langlade. Diatoms made up 96 percent of the algal biomass. A total of 58 algal taxa were identified at Keshena, including 48 diatom taxa (83 percent). Although diatoms accounted for just 22 percent of the algal relative abundance, in cells per square centimeter, diatoms contributed 91 percent of the total algal biomass. The overall biological integrity of the Keshena and Langlade sites, based on diversity, siltation, and pollution indexes for diatoms is excellent.