Is there a reason why the name of lake sometimes appears in front and others it behind for instance Lake Tahoe vs Folsom Lake?

There is no specific rule that determines whether the name of a lake appears before or after the word "lake." It is a matter of style or preference rather than a grammatical rule.

In general, when the lake is well-known or has historical significance, its name may be placed before the word "lake." For example, "Lake Tahoe" is often referred to without the definite article ("the") because it is a famous lake known worldwide. Similarly, "Lake Michigan" is usually mentioned without the article due to its popularity.

On the other hand, when a lake is less well-known or when there are multiple lakes in the same region, the word "lake" may come before the name. For instance, "Folsom Lake" is placed after the word "lake" since there are several named lakes in California in which "lake" might be a part of their proper name.