Mettur Dam Water Levels Drop as Samba Rice Faces Irrigation Shortage in Tamil Nadu

Mettur Dam Water Levels Drop as Samba Rice Faces Irrigation Shortage in Tamil Nadu

Coimbatore, September 12, 2026 — A sharp decline in water inflow to the Mettur Dam is putting samba rice cultivation in Tamil Nadu's Cauvery Delta at risk, with farmers warning that the reservoir's rapidly dropping levels may not be enough to sustain the critical growing season ahead.

The reservoir, which sits at the intersection of Karnataka and Tamil Nadu and serves as the primary water source for millions of acres of paddy fields in the delta region, has seen inflow drop from 8,993 cubic feet per second (cusecs) on September 7 to just 1,174 cusecs by September 12. This represents an 87 percent reduction in five days, raising urgent questions about water availability for samba rice—the region's second major cropping season that typically runs from October through March.

Dam Levels Fall Below Sustainable Thresholds

The Mettur Dam's maximum water level is set at 120 feet, but as of Friday, September 12, the reservoir stood at just 89.67 feet—down from 91.28 feet on September 9 and 90.52 feet on Thursday. The decline comes despite a directive from the Cauvery Water Management Authority (CWMA) instructing Karnataka to release 6,000 cusecs of water daily to Tamil Nadu for a 15-day period.

The situation has left farmers and water management authorities concerned about the upcoming samba cultivation cycle, which requires consistent irrigation during the initial planting and transplanting stages. The reservoir is currently still releasing 12,400 cusecs for irrigation, but officials warn that without sustained inflow from Karnataka's upstream dams, this rate may not be sustainable.

Historical Water Management Tensions

The Mettur Dam dispute has long been a flashpoint between Tamil Nadu and Karnataka, with seasonal water sharing agreements regularly tested by rainfall patterns in the Western Ghats. The CWMA was established to manage inter-state water allocation, but enforcement depends on monsoon performance and reservoir levels upstream.

This year, the situation is particularly acute. While Karnataka has completed harvesting its first crop, Tamil Nadu farmers are in the critical samba planting phase. The water released over the past 45 days has proven insufficient to meet current irrigation needs, according to local agricultural officials.

Farmer Concerns and Agricultural Impact

C. Nallasamy, secretary of the Tamil Nadu Federation of Farmers Associations, said the situation is already challenging for delta farmers trying to save their drying crops. "It has been difficult for farmers to protect their samba paddy, especially as Karnataka has already completed harvesting its first crop," Nallasamy said. "If water flow does not increase significantly in the coming days, the availability could further diminish, putting immense pressure on farmers and threatening their crops."

Samba rice is a critical crop for Tamil Nadu's food security, with the delta region accounting for a significant share of the state's rice production. Any shortfall in samba output would have ripple effects on grain supplies and farmer incomes across the region.

Technical Details of the Crisis

The dam's current release rate of 12,400 cusecs appears high relative to the inflow, suggesting that water is being drawn from stored reserves rather than incoming flow. At the current rate of decline, the reservoir could approach operational minimums before the samba season reaches its peak demand period.

Experts note that samba rice typically requires 120-150 days of consistent water availability. With the reservoir at 89.67 feet and inflow reduced by 87 percent since September 7, the margin for error has narrowed significantly.

Regional Implications

The Mettur Dam situation reflects broader water stress patterns across the Cauvery basin, where climate variability and population growth are increasingly straining shared resources. The 15-day release window ordered by CWMA represents a short-term fix, but long-term sustainability depends on upstream reservoir management and coordinated policy across state lines.

What's Next

Water management authorities are monitoring the situation closely. If Karnataka cannot maintain the 6,000 cusecs daily release, Tamil Nadu may need to consider alternative arrangements, including drawing down additional stored reserves or adjusting planting schedules. Both options carry economic costs for farmers.

The next major decision point comes in the coming weeks, as samba seedlings begin their most water-intensive growth phase. Without sustained inflow, farmers may need to fallow portions of their acreage—a costly move that could affect the region's agricultural output through early 2027.

Sources: Daily Kiran (September 12, 2026); Cauvery Water Management Authority directives; Tamil Nadu Federation of Farmers Associations