Adilapidated, abandoned building on the quiet shores of Kazakhstan's Lake Balkhash is a stark reminder of a fishing industry in rapid decline. The doors to the facility are locked, but its Soviet-era murals - proud fishermen standing lakeside amid a bountiful catch - are easily visible through the missing roof and broken windows. Fishmongers in the nearby market describe shrinking catches and rising prices. The Balkhash fishery's problems are myriad, including pollution and the ill-conceived introduction of predatory species. The lake's constantly fluctuating water levels also take a major toll, and experts warn that increased diversion of the rivers supplying Balkhash may seal the industry's fate. Upstream along Balkhash's main feeder river, the Ili, four elderly Chinese farmers survey a land of plenty. Their major concern is not the size of their substantial wheat and corn yields, but what price they can fetch in the saturated market of Yining, Xinjiang, the closest Chinese city to the Kazakh border. It is hard to imagine a drought affecting the verdant, well-irrigated fields, and indeed, none of them can remember one. Nor have they heard of water problems downriver. Hundreds of kilometres and a political frontier separate Balkhash's fishmongers from Yining's farmers, but the Ili river brings the two distant communities together in their reliance on one resource. 'That border is an abstraction. In nature there are no borders,' said Mels Eleusizov, chairman of Kazakh civic group Nature. Mr Eleusizov, a middle-aged man with thick, wavy hair and the leathery skin of an outdoorsman, seems to have a penchant for lost causes. He has twice run for president, a futile effort in a country that has been led by one man, Nursultan Nazarbayev, since it was part of the Soviet Union. His goal was to draw attention to environmental issues amid the country's oil rush. Outside campaign season, Lake Balkhash ranks highly on Mr Eleusizov's list of uphill battles. The UN Environment Programme warns of a potentially disastrous fall in the level of the lake - the 15th largest in the world, and second in Central Asia only to the Aral Sea - if upstream water use increases as expected. Balkhash has a watershed covering 400,000 sqkm and hosts a fifth of Kazakhstan's 15 million people, including its largest city, Almaty. Its extreme shallowness - averaging less than 6 metres - makes it especially vulnerable to evaporation and salinisation. Haunting the region is the legacy of the Aral Sea, a poster child for poor water management that began shrinking dramatically in the 1960s, ruining the livelihood of thousands. Kuanysh Isbekov, director of the Balkhash branch of the Kazakh Fishing Industry Centre, said Chinese overuse of the Ili was a dire threat to the lake. If diversions increased, as was rumoured, 'Balkhash will undoubtedly become another Aral Sea. It will be an ecological catastrophe,' he warned. Mr Isbekov said the lake was likely to dry up into several parts, devastating fish stocks. Also, less water would be available for farming and drinking and the area's plants and wildlife would be replaced by empty desert. Some, including Mr Eleusizov, say that the damage will eventually threaten Almaty's water reserves, because airborne salt from desertification can settle on nearby glaciers and make them melt faster. The lake's water supply problem is twofold. High in the mountains of Central Asia and western China, global warming is steadily eroding the glaciers that supply Balkhash's rivers. According to Igor Malkovsky, deputy director of the Kazakh Institute of Geography, glacial melt accounts for part of the current cyclical upswing in Balkhash's water level. But the annual 1 per cent decrease in the glaciers' size means the lake is drawing from an ever-dwindling account. 'Until 2010, the flow will not change substantially,' Mr Malkovsky said. 'But by 2020, we clearly expect a drop in water resources due to natural climate conditions,' he said, perhaps by as much as 20 per cent. Compounding this global issue is a local one: the diversion of the area's rivers for human use. Although in square kilometres China accounts for a small portion of the Balkhash basin, its rapid development and possession of the Ili's headwaters puts it in a position to determine the lake's future. Xinjiang, the autonomous Chinese region that includes Yining, is thirsty country, blanketed by two huge deserts and with one of the driest climates on the mainland. Beijing's desire to develop the area is ultimately dependent on water for industry, agriculture and energy. To Chinese planners, the green land around Yining is more than an oasis - it is a resource. On the outskirts of the city itself, new apartment buildings spread in all directions, evidence of the influx of new residents. Pan Junling works for a local real estate firm. She left Henan province for Yining in 2003, following her husband, who served in the army. Enticing newcomers to buy property on a weekday morning, Ms Pan said business was booming. The region's relatively high salaries and less dense population have drawn many from China's interior, creating greater demand for water, food, and energy. The extent of Chinese development plans for the upper Ili and its tributaries remains unclear. A map of the Chinese part of the Ili valley produced by the Kazakh Institute of Geography is peppered with hydroelectric stations, some already functioning, others planned. Irrigated fields spread along both sides of the river's length. One resident said the regional government had been promoting the Yining area as 'the breadbasket of Xinjiang'. Mr Malkovsky said his institute had estimated that in the next few years Chinese diversions of the Ili would increase almost by half, from 5 million cubic kilometres per year to 7.4 million. A local Chinese official working on environmental issues countered that his government was planning to take much more - at least twice the current amount. The official, who spoke on condition of anonymity, said the river system was seen as a solution to water problems in Xinjiang's less fertile areas. 'We don't want a lot of water to flow to Kazakhstan - we just want to cut it off and send it to less populated [Chinese] areas,' he said. The official said his political superiors drove the decision despite opposition from some in local government. 'We said that if we draw water resources from the Ili, we will cause many environmental problems, but they didn't listen.' Abdusalih Nurbay, a professor of ecology at Xinjiang University in the regional capital, Urumqi , denied China was the main cause of Balkhash's problems. Instead he pointed to poor oversight by the Kazakhs and a lack of co-ordination between China, Kazakhstan, and Kyrgyzstan, which also controls a small portion of the basin. 'The Aral Sea and Lop Nur are already dry, and we don't need another one,' Professor Nurbay said, referring to a Chinese lake turned nuclear test site that disappeared due to excessive irrigation. The solution, he said, was to form a plan for joint, sustainable management of the Balkhash region, a project he was embarking upon with colleagues from the neighbouring states. Kazakh experts agreed that the lack of information-sharing between countries was a big obstacle, and several said the Chinese had not been forthcoming about their plans. 'We need a serious international study,' said Mr Eleusizov. 'No one is doing this - our institutes are silent. Maybe China is doing something, but we need to do this jointly.' Iskandar Mirkhashimov, project manager for a European-funded initiative to develop an integrated management plan for the Ili-Balkhash basin, said the decision to co-operate had to be made by political leaders. A 2001 agreement between China and Kazakhstan mandates consultations on cross-border water use, but the talks have produced no agreement. During the most recent talks in March, Beijing rejected a Kazakh proposal to provide free or discounted food to China for letting the Ili flow as before. Eric Sievers, an environmental lawyer who has studied Central Asian water issues, pointed to the construction of a major canal on the Irtysh river in the 1990s as an indication that the Chinese were unlikely to consider the opinions of downstream states. The 300km-long channel, which supplies water to the Xinjiang oil town of Karamay, is thought to drain off as much as 40 per cent of the river's flow. It was built in the face of protests from Kazakhstan and Russia, which also rely on the Irtysh for water. Despite the requirement for consultations on any diversions, the 2001 Sino-Kazakh river agreement was actually a 'coup' for China, said Mr Sievers. It said neither country could limit the other in the use of shared rivers. Kazakhstan, therefore, effectively 'ceded all its rights under international law', Mr Sievers said. Lee Seungho is a specialist in Chinese water policy at Britain's University of Nottingham. He said China's uncompromising position during negotiations over the use of other river systems, such as the Mekong, showed that 'invaluable resources' such as water trumped its relations with neighbours. 'China's approach is very much focused on national sovereignty,' Mr Lee said. He said the bargaining power of downstream states was low, given China's dominant economic position. Kazakh oil exports to China have been growing steadily, and the two countries inaugurated a 960 km-long pipeline last year that is designed to carry 20 million tonnes of oil annually. Mr Mirkhashimov took a longer-term view: 'Nature is like a boomerang - it always comes back at you. It always gives an answer.'