Final answer:
The construction of dams caused detriment to Indigenous populations by causing loss of agricultural land, destruction of habitat, and cultural disruptions due to relocations and prioritization of industrial growth over environmental and traditional interests.
Step-by-step explanation:
The building of dams in the 20th century was detrimental for the Indians primarily because of the loss of agricultural land. Settlements and expansion into less populated regions often caused conflicts between new settlers and the Indigenous populations who already lived there. The construction of large dam projects, such as the Three Gorges Dam, led to the relocation of populations, flooding of historical and archaeological sites, and destruction of habitat. Moreover, these projects often prioritized urban and industrial growth over the environmental and cultural needs of Indigenous communities, further contributing to the depletion of resources and traditional ways of life. The negative impacts were not limited to a single region; dam projects across the United States led to similar ecological damages and cultural disruptions, exemplified by population declines in fish species due to altered river flows and habitat loss.