Ecological problems of water resources in Kazakhstan Тurgai Alimbaev, Bibizhamal Omarova, Samal Tuleubayeva, Bekzhan Kamzayev, Nurmuhammed Aipov and Zhanna Mazhitova E3S Web Conf., 244 (2021) 01004 Published online: 19 March 2021 DOI: 10.1051/e3sconf/202124401004