She had written a similar kind of letter to the prime minister even in May 2012. Like last year's letter, she says in today's letter that reports had suggested that the Karnataka government has constructed a diversion structure for diversion of water.
"This act of Karnataka will affect the (water) flow in the river considerably and will severely affect the irrigation in Tamil Nadu depending upon the waters of the inter-state Pennaiyar river," she said.
The river flows through the districts of Krishnagiri, Dharmapuri, Thiruvannamalai, Villupuram and Cuddalore in Tamil Nadu. It runs south and then east for 400 km through Karnataka and Tamil Nadu, emptying into the Bay of Bengal at Cuddalore.
It originates in Nandi Hills, just outside Bangalore city and has water for very few months. It is also highly polluted river with sewage water of Bangalore flowing into the river through Varthur lake.
The river is dry for the most part of the year and its sand is most treasured in the area. Water flows during the monsoon season when it is fed by the southwest monsoon in catchment area and the northeast monsoon in Tamil Nadu. It also acts as source of groundwater throughout its journey.
However, pollution studies reveal that the groundwater in many places is contaminated by higher concentrations of NO3, Cl, PO4 and Fe. The level of salinity, sodium adsorption ratio, and sodium percentage indicate that most of the groundwater samples are not suitable for irrigation as well as for domestic purposes and far from drinking water standards.
In May 2012, she had said "I understand that the Government of Karnataka has proposed to construct check dams and diversion structures across the Pennaiyar River, which is causing great alarm and apprehension in Tamil Nadu. Any attempt to withhold the flows by constructing check dams and diversion structures across the Pennaiyar River will be a serious breach of the existing Inter-State Agreement on this issue. This will also be a body blow to the farmers of Tamil Nadu besides affecting the basic drinking water supply position," she said in a statement.
Jayalalithaa further said that Pennaiyar is an Inter-State River and is also one of the rivers mentioned in Schedule ‘A' annexed to the Madras-Mysore Agreement of 1892.
The clause-II of this Agreement states that the upstream State should not, without the previous consent of the downstream Tamil Nadu State, build any new anicut or a dam or any structure to obstruct, divert or store the waters of the river across any part of the river.