Arnolds Park is a city in Dickinson County, Iowa, United States. The population was 1,110 in the 2020 census, a decline from the 1,162 p…Arnolds Park is a city in Dickinson County, Iowa, United States. The population was 1,110 in the 2020 census, a decline from the 1,162 population in the 2000 census. Arnolds Park is located at 43°21′56″N 95°7′47″W / 43.36556°N 95.12972°W.