Farming in Bihar hit by siltation in major canal systems: CAG

PATNA: Heavy siltation of major canal systems, including the Eastern Kosi Canal System (EKCS), the largest major irrigation project of Bihar, is now proving to be a bane for the state since it has resulted in low water discharge and ultimately affecting the crop production, the Comptroller and Auditor General of India (CAG) report on the outcomes of surface irrigation projects in Bihar revealed.
As per the report, a total of 85.41 lakh hectares were to be irrigated during the period of 2015-2021 against which irrigation was provided to 59.87 lakh hectares (70%) only. However, the audit observed that the report of the Water Resources Department was not correct.
“As per net availability of water in the canal system and duty of water decided by the department, irrigation was possible in maximum 21.37 lakh hectares (25%) only,” the CAG report said, attributing low irrigation to various factors such as siltation and deficient planning of construction of settling basin.
The report states that due to heavy siltation in Kosi river, canal flow capacity of the head reaches of the main canal and branch canal have gradually reduced. The Kosi project is an international project between India and Nepal in accordance with the Indo-Nepal Agreement of 1954, subsequently revised in 1966. The barrage, canal head works and head reaches of the canal fall in Nepal and lower reaches of canal in Indian territory. The project was finally closed in March 1985 after an expenditure of Rs187.16 crore, the report states.
“Audit report observed that the designated discharge capacity of EKCS was 15,000 cusec. However, average water discharge during the kharif season was 5,215 cusec (35%) only during 2015-2021. Lower discharge than designated water discharge capacity was due to siltation and damaged/defunct structures,” the CAG report mentions.
According to the report, the settling basin was constructed at the cost of Rs68.53 crore in the Eastern Kosi Main Canal System (EKMCS), up to two metres deep below the canal bed level, to “trap the silt coming from Kosi river in the system to provide silt-free water to hydel power project and irrigable land”. For dredging of silt from the settling basin of the EKMCS, an agreement was even executed (September 2015) with a contractor for five years. “Though the contractor was to remove silt of 7.70 lakh cum from settling basin, he actually removed 7.70 lakh cum silt lying above the level of settling basin leaving 10.88 lakh cum of silt in and above settling basin,” the report reveals.
The report says the Eastern Gandak Canal System (EGCS), the third largest surface irrigation project, too remains affected with heavy siltation resulting in low water discharge. “Audit observed that the designated water discharge capacity of EGCS was 12,480 cusec. However, average water discharge was 7,024 cusec (56%) only during 2025-21. Lower water discharge was due to siltation and damaged/defunct structures,” the report stated.
The audit also found that though the post-project yield increased in the areas covered by this project, yet this was not mainly attributable to the surface irrigation. The use of private tube wells was the main reason for the increase of yield in the project command area. “During beneficiary surveys, it was found that 76% farmers were dependent on other sources of irrigation, including use of private tube wells in the areas of EGCS,” the report said.