Minnehaha is a census-designated place in Clark County, Washington, United States. The population was 11,871 at the 2020 census. This area got its name from a Columbian newspaper editorial in 1891. The editor wrote about Burnt Bridge Creek and called it "Minnehaha, laughing water," from Longfellow's poem "The Song of Hiawatha". The name appealeā¦Minnehaha is a census-designated place in Clark County, Washington, United States. The population was 11,871 at the 2020 census. This area got its name from a Columbian newspaper editorial in 1891. The editor wrote about Burnt Bridge Creek and called it "Minnehaha, laughing water," from Longfellow's poem "The Song of Hiawatha". The name appealed to the citizenry and they kept it. Before that the area was called the "Black Forest" for its thick timber.