(CNN) India's top court may have finally ended a centuries-long, and at times bloody, dispute over the allocation of water from a river to states in South India.

The country's Supreme Court's solution to the age-old problem has turned out to be simple -- a fixed allocation of water for the next 15 years to the states bickering over it, and the creation of an independent body to regulate the release of water from the Cauvery river.

The states of Karnataka, Tamil Nadu and Kerala, along with the union territory of Puducherry, all claim a share of water from the 475-mile-long Cauvery, which originates in Karnataka and flows into neighboring Tamil Nadu before feeding into the Bay of Bengal. The river basin, meanwhile, extends into Kerala and Puducherry.

The Supreme Court said Karnataka will receive 284.75 thousand million cubic feet (TMC) of water from the river each month for the next decade and a half — 14.75 TMC more than its previous quota. Tamil Nadu, meanwhile, would get 177.25 TMC, lower than what it used to receive.

Why the court cut Tamil Nadu's allocation

Tamil Nadu's allocation was reduced because of the ground water resources available to the state, while Karnataka's share was increased to ease the strain brought about by a string of droughts. The state's quota was also raised to provide drinking water for its fast-growing capital, Bengaluru — India's original tech hub, home to campuses of many Indian and US tech giants, including Infosys, Microsoft and Google.

Kerala and Puducherry will continue to receive 30 TMC and 7 TMC, in line with earlier settlements.

The court also ordered the creation of an independent board within four weeks to control the allocation of the river's water, saying the Cauvery Management Board will be "entrusted with the function of supervision of the operation of reservoirs and the regulation of water releases".

The decision was welcomed by environmental activists.

"The river should not be the possession of any one state. It is a common public trust. People are the owners and the state is merely a custodian but the states have become dogmatic about their custodianship. They have started using their rights as territorial rights. So, just because Karnataka has won in terms of legality, does not mean this is a time for celebration. It is a time for greater responsibility," Leo Saldanha, a founding trustee of the Bengaluru-based Environment Support Group, told CNN.

"The Supreme Court is reminding us of the constitutional mandate, that we have to take care of our common resources as people and that it should not be divided by the borders of states."

Saldanha also welcomed the court's decision to increase Karnataka's allocation.

"The allocations that have been increased for Bengaluru provide a certain type of elasticity in its growth and political incentive to expand the city. The larger point is that in Karnataka, we should be more responsible in terms of how we use our water for agriculture and urbanization in the Cauvery Basin," said Saldanha.

However, politicians in Tamil Nadu expressed frustration at the court's decision.

Actor-turned-politician Kamal Haasan said he was "shocked" at the reduction in the supply of water to Tamil Nadu.

"But I think the Supreme Court firmly said that water cannot be owned by any state. That's a consoling factor," he said at a press conference in the state capital, Chennai.

"I think now, instead of letting politicians meddle for their vote hunt, we should see that amity is maintained between the two states and the Tamil farmers should think about conserving whatever water we're getting. The people of Tamil Nadu should work hand in hand to see how we can conserve the water."

MK Stalin, a former mayor of Chennai and deputy chief minister of Tamil Nadu, decried the ruling and said the state has been "betrayed" by the reduction.

A contentious issue

Farmers in both states rely on the Cauvery to irrigate their lands. It is also a vital source of drinking water after the monsoon rains wind down in southern India in September.

The dispute over Cauvery's waters date back to the early 1800s, according to government records. The disagreement has resulted in multiple settlements in the past but none have resolved the issue.

The Cauvery water dispute erupted into violence on September 12, 2016. (MANJUNATH KIRAN/AFP/Getty Images)

In September 2016, riots broke out on the streets of Bengaluru after a Supreme Court ruling ordered the state to release 15,000 cubic feet of water per second per day (cusecs) from its reservoirs to relieve drought-stricken farmers in Tamil Nadu.

After rumblings of unrest, the Supreme Court reduced the level of water that had to be released to 12,000 cusecs each day until September 30. Violence erupted after the court refused Karnataka's request for a further reduction.

Demonstrators vandalized shops and set fire to more than 100 cars, buses and trucks in Bengaluru.

Thousands of police were deployed in the city in an attempt to regain control, while authorities banned large gatherings and imposed a curfew in several areas.

Two people were killed in the unrest.

2016 wasn't the only time the issue of the Cauvery's water resulted in violence. The long running dispute has triggered other incidents in the past, including the 1991 anti-Tamil riots in Karnataka which resulted in a slew of xenophobic attacks against the state's Tamil population and their homes and businesses.

Ahead of today's verdict, security was ramped up in Bengaluru as well as Chennai. Public bus services were reduced in both cities.

The US Consulate in Chennai also issued an advisory, warning American citizens that demonstrations could take place in light of the verdict.

In recent years, the issue has become heavily politicized, with Tamil Nadu claiming it has not received enough water and blaming its neighbor for holding it in its reservoirs.

CORRECTION: This story has been updated to provide the correct quotation for Leo Saldanha.