This study describers a Health Impact Assessment (HIA) to identify issues associated with the Ping River which affect public health. The first step in the project, scoping, has been conducted for 8 months, from December 2002 to July 2003. The main objectives of the project are 1) to study 4 dimensions  (physical, mental, social and spiritual) of the public health issues associated with the Ping River; 2) to identify the impacts from those public health problems; and 3) to create learning processes at the local level, which will lead to development of better public policy.	The study area was three districts in Chiang Mai Province (Mae Rim, Muang and Saraphree). Each of these districts lie on the Ping River. The main differences between them are in land use. Mae Rim, the northernmost (upstream) District, is rapidly urbanizing from a rural basis, because of its many popular tourist attractions and its position on the main highway north from Chiang Mai. Agriculture is still extensive around Mae Rim. Muang District, in the central part of Chiang Mai province, has a relatively high population density. Here the dominant uses of the Ping River are residential and leisure activities. There are many restaurants on the river banks and the scenery is quite beautiful. The southernmost and most downstream district is Saraphree. This is still a rural area and local culture has been retained. The three districts are connected by the Ping River and share a similar geography, human society and ecology. Any changes in the river’s upstream character will be transmitted to the downstream areas and may influence the physical, mental, social and spiritual dimensions of public health.	The realization of the need for effective decision making by governmental organizations which can affect the Ping River, and which can impact local communities in both positive and negative ways, produced a brainstorming seminar between researchers of this project and government representatives from the local and central levels. In the past, local government officers have conducted many missions, without approaching the public for advice, which have promoted resistance to government ideas and a lack of public participation as a consequence. There has also been overlap in the activities of some different government organizations, which has resulted in waste of time and loss of public money. After the brainstorming sessions, more than 500 questionaires were issues to the public living in the areas of study, asking them how issues related to the Ping River related to the 4 dimensions of public health described above. The results of the survey showed that the most serious for the public was loss of access to the Ping River. The river was reported to be narrower and shallower than before, because of soil erosion from the banks and intrusion of businesses into the river area. These issues affect the 4 dimensions public health as follows: 1) Social public health is affected because of fewer traditional cultural activities; 2) the mental health of the population is reduced due to irritation over poorer water quality and/or riverbank intrusions; 3) physical health is worse because of rashes from contact with river water; and 4) spiritual  health can be negatively affected by human intrusions into the common river area for private personal benefit without community agreement. Spiritual health can also be affected positively, through the retention of culture and tradition, which respects and values the river.	An analysis of the answers and responses from the questionaires was presented to the “Ping River, Environment and Public Health Meeting”, attended by many stake holders. The aim of the meeting was to inform the public, listen to the response and share ideas about the issues. The meeting concluded that the main problems were; 1) Uncontrolled urban development, which caused contamination of water, improper land use along riverbanks and loss of local cultures and traditions; 2) Lack of public participation in decisions over the usage and care of the Ping River, which allowed individuals and small groups to gain  personal  benefit, and avoid law enforcement; 3) Lack of knowledge of consequences of their actions by managers causing more problems, such as changing the direction river flow increasing bank erosion and concrete  construction that ruined river scenery.	These issues arose because some government organizations and members of the public still lack appreciation for the importance of conserving the Ping River. The three issues mentioned above could be solved by a public relations program to promote the appreciation of the value of the Ping River to  the  community. Also government must act with understanding on issues in each particular area and address the real cause of the problems. It is most important to listen to public concerns and get both public and non-governmental organizations, which can be important contributors to policy, to be involved together in the successful long term protection of the Ping River and for sustainable local development.