Analytical results from extracts of semipermeable membrane devices (SPMDs) from Milwaukee-area streams included evidence of potential toxicity to macroinvertebrates and fish due to synthetic organic compounds in water (table 22). WWC results can be compared with toxicity results by individual WWC constituent as well as by WWC class. In general, the same constituents at the same sites appeared in both SPMD results and WWC results; WWC results indicated where the constituents were occurring at high frequencies, whereas SPMD results indicated that these constituents had the potential to accumulate in fish tissue. For the remaining eight sites that were not sampled for SPMDs, the WWC data could indicate which sites would be of interest for further toxicity testing in Phase III.

Table 22. Results for toxicity tests and selected chemical analyses of semi-permeable membrane device (SPMD) extracts and detection frequencies for Phase II wastewater-compounds (WWCs) analysis at seven sites in the Milwaukee Metropolitan Sewerage District planning area, Wis.

[pg TEQ/mL SPMD, picograms of 2,3,7,8-tetrachlorodibenzo-p-dioxin per milliliter of SPMD extract; µg PAH/mL SPMD, micrograms of polycyclic aromatic hydrocarbons per milliliter of SPMD extract; mg eq SPMD/mL DSMO, milligram equivalent SPDM extract per milliliter dimethyl sulfoxide; ng/SPMD, nanograms per total SPMD; <, less than; all SPMD values in time-normalized (30 days) concentrations; all WWC values in detection frequencies; units for Microtox EC50 are for the 50-percent-effective concentration]

¹ SPMD data was collected as part of the U.S. Geological Survey National Water-Quality Assessment Program (NAWQA) Effects of Urbanization on Stream Ecosystems Topical Study. For these three MMSD Phase II sites, three nearby NAWQA sites were sampled: Underwood Creek at Watertown Plank Road at Elm Grove (about 3 miles upstream of Underwood Creek at Wauwatosa), Honey Creek near Portland Avenue at Wauwatosa (about 1 mile upstream from Honey Creek at Wauwatosa), and Root River at Layton Avenue at Greenfield (about 2 miles upstream from the Root River at Grange Avenue at Greenfield).

Cytochrome P450RGS tests indicated potential toxicity from the presence of compounds like dioxins, PCBs, and PAHs in streamwater at all seven sites, with the highest potential toxicity at the Little Menomonee River, Root River at Grange Avenue, Oak Creek, Lincoln Creek, and Honey Creek sites (SPMD data for the Root River at Grange Avenue, Honey Creek, and Underwood Creek Phase II sites actually were sampled at nearby USGS NAWQA sites; see page 14 for more details).

Fluoroscan results indicated the presence of PAHs at all seven sites. The highest concentrations of PAHs found during 2004 were at Little Menomonee River and Menomonee River at Menomonee Falls. The concentration for Little Menomonee River was nearly twice that for Menomonee River at Menomonee Falls; concentrations for Root River at Grange Avenue, Honey Creek, Lincoln Creek, and Oak Creek were also high compared to other sampled sites. In addition to other sources, high concentrations of PAHs have been found in coal-tar-based sealcoats used on parking lots that break down over time and allow PAHs to be washed into waterways with runoff (Mahler and others, 2005).

Microtox tests indicated higher potential toxicity at the Underwood Creek site than at all other sampled sites in the Milwaukee area, suggesting that compounds other than those detected in the P450RGS or Fluoroscan tests were causing toxicity to the bioluminescent bacteria used in the Microtox test. Phase II results were examined for potential sources of this toxicity. Of the WWCs, 9,10-anthraquinone, and tris(2-butoxyethyl) phosphate had high DFs at Underwood Creek, and elevated concentrations of lead were found in bed sediments at this same site.

Chemical analyses of the SPMD extracts found the presence of several PAHs. The PAH phenanthrene was highest at the Menomonee River at Menomonee Falls site (750 ng/SPMD), but was also relatively high at the Root River at Grange Avenue (590 ng/SPMD), Honey Creek (380 ng/SPMD), and Little Menomonee River (340 ng/SPMD) sites; SPMD results for anthracene, another PAH, indicated its presence in these four streams as well. Phase II results from WWC data analysis in water indicated that phenanthrene was present at all the same sites at a DF of 50 percent or greater. The site with the highest detections of phenanthrene was Underwood Creek (100 percent), followed by Root River at Grange Avenue (77 percent) and Little Menomonee River (75 percent). WWC water analysis indicated anthracene was present at low DFs (33 percent or less) in 5 of the 7 sites, and absent at Menomonee River at Menomonee Falls and Oak Creek.

SPMD results for pyrene and fluoranthene had the highest concentrations at the Little Menomonee River (1,700 and 1,640 ng/SPMD, respectively), Root River at Grange Avenue (2,100 and 1,600 ng/SPMD, respectively), and Menomonee River at Menomonee Falls (1,900 and 1,300 ng/SPMD, respectively) sites. Naphthalene was found only in the SPMD results for Little Menomonee River, whereas methylnaphthalene compounds were found at Little Menomonee River and Root River at Grange Avenue. WWC results for pyrene indicated the highest DFs at Underwood Creek (100 percent), Little Menomonee River (83 percent), Root River at Grange Avenue (77 percent) and Honey Creek (75 percent). WWC results also indicated 100-percent DFs for fluoranthene at Little Menomonee River, Underwood Creek, and Root River at Grange Avenue. WWC DFs for naphthalene were relatively low at all sites (33 percent or less), even though it was detected at 5 of the 6 sites; DFs for 1- and 2-methylnaphthalene were even lower than those for naphthalene (25 percent or less).

Overall, results for toxicity tests (performed on SPMD extracts) and individual constituent analyses (performed on both SPMD extracts and water) from Little Menomonee River had moderate to high concentrations and DFs, and indicate that PAHs may be an issue of particular concern at this site. Contamination at this site may be attributed to the Moss-American Superfund site located upstream.

In summary, the combination of WWC results, in concert with toxicity tests and chemical analyses based on SPMD results, confirmed that concentrations of some synthetic organic compounds were of concern to aquatic biota in MMSD-area streams.

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