Some characteristics of Realism in literature are that the characters resemble ordinary people in ordinary circumstances, the characters often meet unhappy ends, the dialogue resembles ordinary speech, and the settings are places that actually exist or could exist. "The Luck of Roaring Camp" meets all these criteria for realism.
The characters in the story resemble real people in ordinary circumstances. These rough miners and one prostitute are the type of people who actually populated the Western mining towns in the Gold Rush years. Certainly prostitutes were a common enough feature of such towns, and Stumpy, a polygamist who had come to the camp as a "city of refuge," also reflects events of the period. Although the characters of Kentuck and the other "roughs" are colorful, they are by no means unbelievable. Of course, these characters meet unhappy ends, especially Kentuck and Stumpy, who die in the flood. The others have their homes washed away and their baby, whom they have loved, taken from them in death.
The dialect Harte uses for dialogue is realistic and gives the story some of its charm. For example, Kentuck says, "I crep' up the bank just now ... and dern my skin if he wasn't a-talking to a jaybird as was a-sittin' on his lap." Stumpy's speech is likewise ordinary for a man like him: "It ain't my style to spoil fun, boys, ... but it strikes me that this thing ain't exactly on the squar."
Finally, the setting seems realistic as described; such mining camps did exist in California during the Gold Rush. Harte places the camp in "the Sierra foothills," and he describes at various points the river, the gulch, a "large redwood-tree," and the rude cabins the men live in. These are all believable, historical features of a mining camp.
Harte's story definitely contains elements of realism because of its characters, the real-life dialect, and the concrete setting of a mining camp during the California Gold Rush.