This is a great question. Dam are important to our country and the sheer number of them show this point well. However, dams have problems as well. They change the ecosystem of a river and this can have adverse long-term effects. In addition, dams are expensive to build and to maintain. So, people need to think twice before building one. In other words, they should think of alternatives.
If the reason to create a dam is to get more drinking water, a community should think of alternate water sources. Can they get water from underground pumps instead? This might be a better option. Can they get water from another place and get it transported in?
If the reason for the dam is to get more electricity, the community might want to consider reducing their need for energy or alternative sources for energy.