Question

1. prior to 1856, chicagos rapidly growing population and flat, swampy terrain led to critical sanitation problems. which of the following best describes the primary source of drinking water contamination in the city during this period?

the reliance on polluted underground wells dug beneath crowded tenement houses.
the frequent flooding and sewers dumping directly into the chicago river and lake michigan.
industrial chemical runoff from the early stockyards that was dumped directly into city water treatment fac ties.
the use of open sewers that were built on the citys surface and flowed into the des plaines river.

Explanation:

In 19th - century Chicago, due to its flat and swampy terrain and rapid population growth, the city's sewers dumped directly into the Chicago River and Lake Michigan. Since the city also drew its drinking water from these water - bodies (before proper water treatment was in place), this led to significant water contamination. Underground wells were not the main source as the city's water supply was more reliant on surface water from the river and lake. Industrial chemical runoff from stockyards was not a primary source compared to sewage dumping. Open sewers flowing into the Des Plaines River were not as relevant to the main water supply (which was from the Chicago River and Lake Michigan).

Answer:

The frequent flooding and sewers dumping directly into the Chicago River and Lake Michigan.