def stations_level_over_threshold(stations,tol):
    """For Task 2B - returns a list of tuples
    The tuples contain a station and then a relative water level
    the relative water level must be greater than tol
    returned list should be in descending order"""
    
    threshold_list=[]
    for station in stations:
        m=station.relative_water_level()
        if m==None:
            pass
        elif m>tol:
            threshold_list.append((station, m))
    
    final_threshold_list = sorted(threshold_list, key=lambda x: x[1], reverse=True)

    return final_threshold_list