When I saw the rice fields in Thailand for the first time I was amazed how split into tiny sections they were in order to follow the natural contours of the land. It's not that I had never seen rice fields before-- after all, rice is one of Arkansas' main exports-- but I expected to see swaths of flat land made uniform by huge earth-moving machinery. Rural Thailand has maintained much of its landscape because of lack of access to such equipment. Life is more ecological simply because there is no other option. But this is changing. Developers have discovered dam building, for one.
As Ben said, it almost doesn't matter whether a stream is polluted because flow is everything and a dam changes flow dramatically and permanently. Once that key determinant of stream health is lost, the system collapses and along with it the livelihoods of many. As Bunn and Arthington describe, altered flow regimes lead to a loss of biodiversity, evolutionary life history strategies, lateral stream connectivity, and native species.
Like local communities on the Mun River, communities on the Yom River have seen the effects of an altered flow regime because of a narrow-minded government project. They are actively fighting against a second project, the Kaeng Sua Ten Dam, that would change the region in which they live even more.
Fifty years ago, an irrigation weir was built downstream of Sua Ten (dancing tiger) rapids that, while benefiting some farmers, caused widespread changes that affected many negatively. Fish were no longer able to migrate upstream because they could not get past the concrete obstruction. Fisheries declined. Paw Songwan told us that of the 80+ species that could once be found upstream of the weir, today only 54 can be found. He described the first year after the weir was built when the area just below was packed with migratory fish hoping to spawn upstream. The villagers' nets broke as they hauled out this one-time bonanza catch. Many of those fish types were never to be seen again in the upper Yom River.
Efforts have been made to support the growth of the non-migratory fish species that can now be found in the upper Yom. Parts of the river have been declared conservation areas and fishing is prohibited or limited. In one section of the river, local people gather once a year to repair a low masonry weir that backs up water and allows larger fish to spawn. Unlike the permanent concrete weir built by the government, this weir uses no adhesives and allows water to flow freely. The larger fish are, for the most part, kept upstream of the obstruction, but nature continues to have the upper hand. The people don't seem to mind the system. As Paw Songwan said, it takes a large group of villagers about half a day once each year to do the necessary repairs.
Weirs like the one described above are a common traditional way of providing several needs. The movable, flexible dams are made of stone or woven from bamboo not only to trap larger fish, but to raise water levels for irrigation as well. Because these obstructions are not permanent, they do little to change or harm the overall health of the riparian ecosystem. Local people realize the importance of a diversity of substrates and water velocities-- each situation provides habitat for different organisms. In the case of any ecosystem, diversity is stability. If disease or another disaster strikes a certain segment of the population, other species ensure that the entire ecosystem does not go haywire.
Unfortunately, quite a bit of money and power is involved in dam-building projects. The technocrats who propose them often ignore the fact that their actions "for the common good" are actually impinging on the rights of thousands of society's most powerless communities. However, activists like those in the village of Don Chai have been changing the game for over 20 years. The whole community is involved-- children, elders, adults of all backgrounds. Unlike Nong Po, Don Chai is still a flourishing town and young people are interested in staying in the community. This does not mean they do not dream big. The members of Dakon Yom, a youth activist group, have dreams of becoming doctors and pilots and policemen, but they have a sense of connection and responsibility to their village, as well. The community has networked with dam activists across the world in incredibly sophisticated ways, managed to inform and inspire their youth to join the fight, and feel hopeful and empowered. The pride each of the people seemed to take in the success of their community was palpable.
Though the villagers of Don Chai rely on the Yom River only secondarily, their homes are in danger of ending up below an oxygen-poor, sediment-heavy reservoir that will pad the pockets of a select few and leave those less powerful with a way of life in shambles. I hope that their fight is successful in ridding the country of the last planned large dam. Perhaps their ways of thinking will encourage those in power to consider longer-term options for sustainable development like planning cities far away from flood zones and resisting water-intensive monoculture farming from taking root.