Collins erklärt backwater so:
1. A backwater is a place that is isolated.
...a quiet rural backwater.
Synonyms: isolated place, backwoods, remote place, sleepy town
2.If you refer to a place or institution as a backwater, you think it is not developing properly because it is isolated from ideas and events in other places and institutions.
in British English:
1. a body of stagnant water connected to a river
2. water held or driven back, as by a dam, flood, or tide
3. an isolated, backward, or intellectually stagnant place or condition
in American English:
1. water moved backward or held back by a dam, tide, etc.
2. stagnant water in a small stream or inlet
3. a place or condition regarded as stagnant, backward, etc.
Collins übersetzt backwater mit "(lit) Stauwasser nt, totes Wasser; (fig) rückständiges Nest"