in the North, surface water quality today is generally good, although there may
be local and seasonal deteriorations. Disposal of untreated sewage from Chiang Rai is a particular
problem. Also, the predicted future water quality is characterised as good, although slightly below the
present level. This is because the effects of increased loadings from a growing population and industrial
expansion are not fully compensated by the improvements obtained by upland reforestation and water
reclamation. The water quality and the aquatic ecosystems are exposed to the combined effects of two
threats: (i) The risk of a reduced stream flow in the dry season, caused by the increased demand for
water; and (ii) the risk of an increased pollution load, caused by population growth, changed lifestyles,
intensified tourism, and intensified agricultural and industrial production. There are no sewered areas in
the basin, and no treatment plants have been established. Sewage stabilisation ponds are under
construction to serve Chiang Rai Town. Industries are typically processing plants for fruits and
vegetables, or noodle factories. They produce mainly organic sewage. Most industries are located around
Chiang Rai, and in the Fang and Upper Lao sub‐basins.