Yes, the word upstream is an adverb.
It is also an adjective.
Some example sentences are:
The salmon are swimming upstream.
You'll find the campsite upstream from here.
upstream
downstream and upstream
Upstream - newspaper - was created in 1996.
The duration of Swimming Upstream is 3240.0 seconds.
The duration of Upstream - film - is 3600.0 seconds.
assembly upstream and downstream in ammetres
when a body moves against the flow, it is known as upstream flow
Swimming Upstream was created on 2003-02-27.
Upstream - film - was created on 1927-01-30.
Upstream - mobile marketing - was created in 2001.
Upstream Print Solutions was created in 1995.
Upstream Print Solutions's population is 300.