Activities done by Cau Sub-RBO in the first 6 months of 2009 were presented and praised at its semi-annual meeting held on June 25-26, 2009 in Bac Giang province. The Sub-RBO has well coordinated among its members in exploiting and allocating water resources in Cau river basin and its sub-basins. The member provinces were also actively involved in river bank protection, reforestation and watershed management, flood control and environment protection in the basin. However, challenges in organization and operation of the Sub-RBO are existent and need greater efforts by the Sub-RBO itself and direction by Ministry of Agriculture and Rural Development and the RRBO for better performance of the Sub-RBO.