Engineering college parts of a university may not require as much foreign language BUT- one first has to get admitted to the university as a whole. Students are competing for spots at UW regardless of intended major.
A BS at UW only requires 3 years (college semesters) of one foreign language while a BA requires 4 of one or 3 of one plus to of a second to graduate in L&S. Therefore, for that school, taking 4 years worth (middle school can count) of a foreign language in HS means meeting any college foreign language requirements unless for a specific (likely foreign language) major. One less requirement in college.
It seems a good idea to do at least the 3rd year of HS Spanish to meet some schools’ requirements and to be more competitive in the admissions process, regardless of proposed major. It also is a good thing to learn another language.