The lower part of the bisse Riederi between the «roti Flüe» and the hamlet Summerseili is still in operation. The differences of the vegetation before and near, respectively above and beneath the bisse are impressive. Meanwhile the wayside near the bisse is lush green, meadows and forests before and above the bisse are dry. This illustrates the importance of the construction of the irrigation channels for agriculture and the local mountain farmers. The milky water comes from the meltwater from the glaciers which contains lots of debris and rock powder. For this reason, our ancestors called the irrigation water also «glacier milk».