Malcolm Ross classifies the languages as an independent family, a position confirmed by Timothy Usher.
Because of the apparent phonological similarities and sharing of stable basic words such as ‘louse’, William A. Foley speculates the potential likelihood of a distant relationship shared between the Skou and Lakes Plain families, but no formal proposals linking the two families have been made due to insufficient evidence.
However, Saponi shares half its basic lexical vocabulary with Rasawa, and Ross left it in the Lakes Plain family pending further investigation.
Ross transferred it to the East Bird's Head – Sentani languages on the basis of pronoun similarities in hopes that this would promote further research.
Although phonetic nasals do exist in most Lakes Plain languages, they do not contrast with the corresponding voiced stops.
Many of the languages have very high constricted (fricativised) vowels; in Doutai and Kirikiri these constitute separate phonemes from /i/ and /u/.
Unlike other Lakes Plain languages which can be disyllabic or trisyllabic, Iau word structure is predominantly monosyllabic.
Bauzi, an East Geelvink Bay language spoken to the northwest of the Lakes Plain family, also does not have gender.
[3] Basic vocabulary of the Lakes Plain languages (Rasawa, Kirikiri, Iau, Duvle, Obokuitai, Diebroud) listed in Foley (2018).