More than 20 lakh people in Ghaziabad and Noida who depend on Ganga water are likely to be affected when the irrigation department shuts Upper Ganga Canal for annual desilting from Oct 21 to Nov 25. In the city, Ganga water is supplied to trans-Hindon areas like Indirapuram, Vaishali, Kaushambi, Vasundhara, Siddharth Vihar, Pratap Vihar and delta colonies like Surya Nagar.