代词的指代问题

…However, the couple is throwing trashes into the river, and lots of garbages are floating on the water; that are so disharmonious.

我想用“that”代指前面的“the couple is throwing trashes into the river, and lots of garbages are floating on the water‘’可以么？

由于是非限制性定语从句，应该用which，另外用单数is。