Central Ground Water Board, Ministry of Water Resources, Government of India

Ground Water is a Precious National Resource - Preserve it, Protect it and Don't Pollute it.

State Profile
Ground Water Scenario of Tamil Nadu

Area (Sq.km)	1,30,058
Rainfall (mm)	995
Total Districts / Blocks	32 Districts

Hydrogeology

Nearly 73% of the total area of the State is occupied by a variety of hard & fissured crystalline rocks like charnockite, gneisses and granites. The depth of open wells varies from 6 to 30mbgl. While the depth of borewells generally varies from 30-100m. The sedimentary formations consist of sand stones, limestones and shales whereas Quaternary sediments in the State represented by Older alluvium and Recent alluvium and coastal sands. In the Cauvery delta of Thanjavur District, the artesian pressure head ranges between 4.5 m to 17 magl with free flow up to 270 m3/hr. The yield of wells in the alluvium varies form 27 to 212 m3/hr. The yield of wells in the fissured formations varies from 7 to 35 m3/hr.

Dynamic Ground Water Resources (2011)
Annual Replenishable Ground water Resource	21.53 BCM
Net Annual Ground Water Availability	19.38 BCM
Annual Ground Water Draft	14.93 BCM
Stage of Ground Water Development	77 %
Ground Water Development & Management
Over Exploited	374 Blocks
Critical	48 Blocks
Semi- critical	235 Blocks

Artificial Recharge to Ground Water (AR)	Area identified for AR: 68839 sq km Volume of water to be harnessed:712.30 MCM Feasible AR structures: Percolation tank- 5388 Check dam/NB- 16163 Recharge Shaft- 154578 Recharge tube well- 743 RT(KM)- 539 Farm pond/Recharge pond-16163
Ground Water Quality Problems
Contaminants	Districts affected (in part)
Salinity (EC > 3000 µS/cm at 25 ° C)	Arriyalur,Chennai, Coimbatore, Cuddalore, Dharampuri, Dindigul, Kancheepuram, Karur, Nagapattinam, Namakkal, Perambalur, Pudukkottai, Ramnathapuram, Salem, Sivaganga, Thanjavur, Theni,Tiruppur, Thiruvallur, Tirunelveli, Trichchirappalli, Tuticorin, Vellore, Villupuram, Virudhunagar.
Fluoride (>1.5 mg/l)	Coimbatore, Dharmapuri, Krishnagiri, Namakkal, Kancheepuram, Puddukotai, Ramanathanpuram, Salem, Sivagangai, Thiruvannamalai, Tiruchirapally, Tiruppur, Vellore, Virudhunagar
Iron (>1.0 mg/l)	Namakkal, Salem
Nitrate (>45 mg/l)	Ariyalur,Chennai, Coimbatore, Cuddalore, Dharmapuri, Dindigul, Erode, Kancheepuram, Kanyakumari, Karur, Madurai, Namakkal, Nilgiris, Perambalor, Puddukotai, Ramanathanpuram, Salem, Sivagangai, Theni, Tiruppur Thiruvannamalai, Thanjavur, Tirunelveli, Thiruvallur, Trichy, Tuticorin, Vellore, Villupuram, Virudhunagar
Heavy metals: Lead (above 0.01 mg/l) Cadmium (above 0.003 mg/l) Chromium (above 0.05 mg/l)	Lead : Dindigul, Tiruvallur, Kancheepuram Cadmium : Tiruvallur Chromium: Cuddalore, Dindigul, Erode, Kanchipuram, Tiruvallur

Central Ground Water Authority

Areas Notified for Regulation of ground water development

Pollachi_S Block of Coimbatore District
Morappur Block of District Dharmapuri
Pappireddipatti Block of District Dharmapuri
Usilampatti Block of District Madurai
Kuttalam Block of District Nagapattinam
Rasipuram Block of District Namakkal
Attur-S Block of District Salem
Gangavalli Block of District Salem
Panamaruthupatti Block of District Salem
Talaivasal Block of District Salem
Veerapandi Block of Salem
Chengam Block of District Tiruvannamalai
Valangaiman Block of District Tiruvarur
Udangudi Block of District Tuticorin
Gudiyatham Block of District Vellore
Jolarpet Block District of Vellore
Pernampet Block of District Vellore
Tiruppathur Block of District Vellore

CENTRAL GROUND WATER BOARD