during flood events the water flow through the weir is increased to lower the water level in the lake the maximum discharge set in the jointly agreed operation rules is mvs conversely the weir is more or less closed in times of drought in order to maintain the water level the overall trophic situation of the shallow lake is mcsoeutrophic lake neusiedl had a good ecological and chemical status in according to the requirements of the wfd since the s and the early s the diffuse nutrient load eg nitratenitrogen has markedly decreased