Chennai Water Facts

Madurai West block status

Draft-to-availability ratio of 105.8% in CGWB's 2024 Dynamic Groundwater Resource Assessment - above the 100% threshold, meaning extraction exceeds annual recharge. Usilampatti is critical at 95.0%; three blocks (Madurai South, Vadipatti, Peraiyur) are semi-critical 70-90%.

GWR2024 blocks classified

Madurai East/West/North/South + 7 peri-urban blocks. 1 over-exploited, 1 critical, 3 semi-critical, 6 safe.

CGWB monitoring stations

CGWB / TN-NHP / TN State GW network across Madurai district. Mix of seasonal manual wells and telemetric DWLR piezometers. Madurai has no MMC ward-level piezometer mesh comparable to Chennai's CMWSSB 200-station network.

HC water-body registry order

Madras HC Madurai bench (R. Manibharathi v UoI) directed TN to publish a public website listing every water body with survey number, location, original and present extent within 6 months. Petition filed over Thenkal Kanmoi and Vandiyur tank bund-road encroachment.

MMC Vaigai cleanup proposal

Madurai Municipal Corporation submitted a Rs 440 crore proposal in 2024 covering pumping-station overhaul plus Vaigai river cleanup. Submitted to TN govt; status: pending sanction.

Over-exploited groundwater blocks (CGWB)

4 of Madurai district's 66 CGWB-classified blocks are pumping faster than recharge. Most stressed: Sindhupatti at 120% development. Latest GWR data 2024.

Critical or semi-critical blocks

Beyond the over-exploited tier, 7 blocks are 'Critical' (>90% draft) and 21 are 'Semi Critical' (>70%). These are the watch-list zones where TWAD / Madurai Corporation interventions need to start before they tip over.

Flagship tanks at critical restoration priority

5 hand-curated flagship tanks score 'critical' on Madurai's restoration-priority composite (status severity × cultural anchor × size × source confidence). Highest score: Vandiyur tank at 100/100.

Flagships at high restoration priority

Beyond critical, 2 more flagships rank 'high'. Combined critical + high = 7 of 19 - the short-list for any Kudimaramathu / Smart City / AMRUT cycle.

F-grade wards on the risk composite

12 of Madurai's 100 wards score F (composite >80) on the 3-factor risk index (groundwater depth 50%, water-body density 20%, water-body health 30%). Highest risk: Ward 88 (SOUTH) at 90.7/100. 34 more wards score D.

Average ward groundwater depth (IDW)

Inverse-distance interpolation from 35 telemetric CGWB stations gives a citywide average water-table depth of 5.1 m. Deepest: Ward 100 at 11.9 m. Refreshes daily as new WRIS readings land.

Vaigai BOD pollution gradient through Madurai

CPCB 2024 NWMP readings: BOD jumps from 3 mg/L upstream of Madurai (Sellur) to 4.2 mg/L downstream (Anuppanadi). Sewage outfalls and textile dyeing through the city push the river over the 3 mg/L drinkable-after-treatment threshold.

Vaigai dissolved oxygen, downstream of Madurai

Latest CPCB NWMP reading at Vaigai D/S Madurai (2024). The 5 mg/L threshold is the cutoff for outdoor bathing and propagation of fish/wildlife under CPCB Class C. Just above threshold.

Urban tank area lost to encroachment

14 fully lost + 12 severely reduced urban tanks. Combined area swallowed: ~16.5 sq km, roughly 30% of Madurai's old city footprint. ~15k slum households now sit on former tank beds.

Vaigai Riverfront Development project

Smart City Mission project: counter-fort retaining walls, walkways, greenbelt, ghats, lighting, e-toilets, children's play areas. Distinct from the Rs 440 crore Vaigai cleanup proposal (pumping-station overhaul + river cleanup, submitted 2024, pending TN sanction). The riverfront project beautifies the bank; it does not address the sand-mining bed-drop that severed the cascade.