The bombings and spraying of Agent Orange during the Vietnam War were some of the factors that led to a serious decline in aquatic resources in Laos. Since the revolution in 1975, the country has seen a trend toward over-fishing due to an array of factors, such as the widespread use of nylon fishing nets, the introduction of the market/money economy, road improvements, the diffusion of ice and cold boxes, and increased exports to Thailand where inland wild aquatic resources are declining. Upstream dams, which are being constructed to generate electricity for sale mainly to Thailand, are dramatically altering the ecology of fish species as well as the stream environments. Similar changes may be caused by irrigation facilities. Deforestation leads to the loss of surface soil, eroding the water retention capacity of mountains and resulting in environmental degradation along the rivers.