Section Overview
A comprehensive 30-year water security plan including restoration of 20,000 water bodies, desalination, the ‘Tamil Nadu Water Security Action Plan 2056’, and new reservoirs. Water management has the highest long-term economic return of any infrastructure investment in water-stressed regions.
Summary Ratings
| Fiscal Pressure | Economic Benefit | Social Benefit | Implementation Risk |
| HIGH | HIGH | HIGH | MEDIUM |
Proposal-by-Proposal Analysis
The table below provides fiscal cost estimates and impact ratings for the principal proposals in this section.
| Key Proposal | Fiscal Cost Estimate | Economic Benefit | Social Benefit |
| Restore 20,000 water bodies over 5 years | ~₹20–30 lakh/tank (desilting + bund repair). 20,000 tanks × ₹25 lakh avg = ₹5,000 cr over 5 years. Partially funded via MNREGS. | HIGH | HIGH |
| Tamil Nadu Water Security Action Plan 2056 (study + implementation) | Plan preparation: ₹30–50 cr. Implementation is a generational commitment – first-phase cost ₹3,000–5,000 cr. | HIGH | HIGH |
| New large reservoirs in water-deficit districts | Unit cost of major reservoir: ₹2,000–5,000 cr. 2–3 new reservoirs = ₹6,000–15,000 cr over 10 years. | HIGH | HIGH |
| Mamallan Reservoir (6th Chennai reservoir) – already laid | Estimate ₹2,500–3,500 cr total project cost (land + construction). | HIGH | HIGH |
| Remove water hyacinth from canals/lakes continuously | Annual contractor cost: ₹50–80 cr/yr statewide. | LOW | HIGH |
| Urban lake restoration with walkways | 500 urban lakes × ₹50–150 lakh = ₹250–750 cr over 5 years. | MEDIUM | HIGH |
Analytical Notes
⚑ Analytical Note: Water investment is among the highest-return public expenditure categories in South Asian states. World Bank South Asia Water Security Report (2023) estimates ₹1 invested in tank restoration yields ₹3–5 in agricultural productivity, groundwater recharge, and flood mitigation over 10 years. The Mamallan reservoir and the 2056 plan are existential infrastructure for Chennai’s long-term water security given the city’s population trajectory.
