Although their incestual relationship doesn't fulfill the criteria of "sexual motivation", it does provide the plot with the sexual aspect of a film noir. J.J. Gittes is the anti-hero of Chinatown. He's as prideful as he is insightful, and he mixes evidence like paint on a palette. His dialogue is composed of lies and accusations, and he's simultaneously abrasive and charming. As previously mentioned, a film noir almost always has a femme fatale. In Chinatown, this role is filled by Evelyn Mulwray. A femme fatale is an alluring and beautiful woman who uses her sexual prowess for her own gain. Evelyn engages in an intimate relationship, yet further along in the film, it becomes evident that Evelyn is in fact the most tragic and pitiful victim in the movie and not a femme fatale. All of these characteristics help frame Chinatown as a film noir. .
Although the film can primarily be labeled as a film noir, there are many more ideas throughout the movie that allow it to be seen as a film with an ecological viewpoint. The first of these is the heavy use of fish and water symbolism. First and foremost, the movie centralizes around a dam building project and the use and conservation of fresh water. The water-rights scandal helps express how ecological misuse of the land occurs in outrageous land-development schemes that redirect the water's flow. It helps remind the viewers that the natural resources of the world are wearing thin due to the selfish manipulations of powerful business men and large corporations. As well as the water scandal, the saltwater pond serves as a symbol for corruption, seeing as how that was where Noah Cross drowned Mulwray. There's also a large use of fish imagery. It seems as though in most scenes a fish can be seen as part of the setting, perhaps as a painting or other sort of wall decoration. Along with this, Noah Cross has somewhat of a "fish mouth".