function enviar_formulario(codigo){  
 		document.formulario.departamento.value=codigo
		document.formulario.submit() 		
}
function JS_saltoMenu(targ,selObj,restore){ //v3.0
  eval(targ+"='"+selObj.options[selObj.selectedIndex].value+"'");
  if (restore) selObj.selectedIndex=0;
}
<!--para oclutar parametros-->
function enviar(codigo){
		var winl = (screen.width - 779) / 2;
		var wint = (screen.height - 470) / 2;
		var caracteristicas = "width=450,height=400,top=" + wint + ",left=" + winl;
		window.open('','nombre_pop',caracteristicas);
		document.formmaps.action='mapsAgencia.asp';
		document.formmaps.target = 'nombre_pop';
		document.formmaps.codigo.value = codigo;
		document.formmaps.submit();
}