The spring rains, plum rains, typhoon rains and north east monsoon rains are a powerful force for soil erosion, but in the ten years since it was filled, the Feitsui Reservoir's water storage capacity has not yet been seriously affected by silting.
北勢溪上游一年四季有雨，春雨、梅雨、颱風雨、東北雨，對土地的沖刷力量也不小，但翡翠水庫蓄水十年，蓄水功能尚未受淤砂影響。