There's a couple things going on here.

The dam is a direct reference to the Johnstown Flood, which is when the South Fork damn failed and there was a substantial loss of life life. Carnegie was linked to the South Fork Fishing and Hunting Club by Henry Clay Frick, a business associate who purchased the reservoir and surrounding land and created the club along with many business partners of Carnegie steel. The basic history of that is that the wealthy members of the club neglected the repairs and maintenance of the dam and on a particularly bad rainstorm it failed. For more info on that I'd direct you to the NPS.Gov Site. Here's the Museum as well.

​

Seeing as the dam failed, and the wealthy were held responsible, including a well known steel baron through association. The reference is that the wealthy and republicans are going to wipe out the poorer people of America with tigher tariffs. The republicans ultimately "Won" the debate and passed the McKinley Tariff Act this increased tariffs to upwards of 50% on goods, and removed others. The logic going that increased tariff's would increase American spending on American goods, lowering tariff revenue, to reduce a surplus that America had at the time. Democrats wanted to lower tariff's to decrease the tariff revenue and lower the surplus that way.

​

As for effects of the McKinley Tariff Act, prices rose on a large number of goods for the American public, and foreign powers viewed it quite negatively. Doug Irwin (Link) published a paper (Link) showing that the Democrat's proposal would have reduced the surplus more than the Republican's version that was passed, which only worked partially due to removing tariffs from sugar. It was very unpopular and in the resulting elections the Democrats swept the government.

​

There was a depression in 1893 called "The Panic of 1893", but this is largely attributed to the Sherman Silver Purchase Act.