Health impact assessments of small dams in the Dogon country, Mali

During the last 40 years, about 108 small dams have been built in the region to support the production of onions, the region"s primary cash crop. Approximately 50% of the dams sustain sufficient water to support one growing season, and 30% will sustain two growing seasons (the first season is from September to January, and the second is January to May). Due to poor siting and/or poor construction, approximately 20% of the dams have failed, i.e., do not hold water beyond the rainy season. The existence of a year-round supply of surface water for agricultural purposes presents potential health risks -- notably, malaria, schistosomiasis, and Guinea worm. Of course, surface water also has potential health benefits such as improved nutrition and hygiene, with an accompanying reduction in skin and eye diseases. Lacking baseline health data, the consultant team"s approach was to look at villages with dams, without dams, and with failed dams to determine if there were significant health risks associated with the presence of dams. The team developed and investigated health, socioeconomic, engineering, and environmental criteria for an impact analysis, visiting 12 villages in all -- 8 with and 4 without dams. The relationship of village water supply and sanitation conditions to water- associated disease was also studied. Health conditions were found to be universally poor in all the villages; problems included high levels of diarrheal diseases, Guinea worm, skin diseases, eye diseases (e.g., trachoma), schistosomiasis, and malaria. Knowledge of basic hygiene and simple proven remedies such as oral rehydration therapy were minimal. Latrines were virtually nonexistent. While all villages with dams also had a source of safe drinking water, most used impounded dam water and/or other unsafe drinking water sources at least occasionally because of convenience or taste factors. Water collection and storage practices were also unsafe in many villages. Not surprisingly, diarrheal disease was reported as the most serious health problem. The eradication of Guinea worm was noted in all cases in which a safe drinking water supply was established and used exclusively for drinking. The only disease found to be specifically related to the presence of dams was schistosomiasis. The Government of Mali (GRM), with the help of the Gesellschaft fuer Technische Zusammenarbeit (GTZ), has been operating a schistosomiasis research and control program in the Bandiagara region for several years. This program was begun in response to GTZ"s concerns about the health effects of small dams they had built in the region. Research to date has shown that although schistosomiasis is endemic to the region, both the prevalence and intensity of infection increased following dam construction. Therefore, GRM"s current strategy is to provide treatment in villages that have dams. The team also concluded that dams may slightly reduce water-washed diseases. The need to incorporate plans for a safe drinking water supply, sanitation facilities, and a hygiene education program into small dam projects is manifest. The most cost-effective and potentially sustainable intervention to address health issues identified during the team"s study were child survival activities. Improved nutrition, an anticipated indirect benefit of the dams, was not investigated but could be assumed to result from improved economic circumstances. Determination of economic benefits of the dams was beyond the scope of this project. Clearly, however, the Dogon people perceive economic benefits associated with small dams. Given the relationship of dams to schistosomiasis, and the existing control program, the team"s recommendations focused on schistosomiasis control and addressed: (1) dam construction, design, and operation; (2) alternatives to small dams; and (3) ways to reduce human contact with unsafe water. The team also identified the need for the Dogon to address marketing issues related to increased onion production. (Author abstract)