During the 1970s, the ecological and economic effects of these projects prompted scientists to seek ways to modify dam operations to maintain certain fish species.
[12] One effort currently underway to restore environmental flows is the Sustainable Rivers Project, a collaboration between The Nature Conservancy (TNC) and U.S. Army Corps of Engineers (USACE), which is the largest water manager in the United States.
Dam reoperation to release environmental flows, in combination with floodplain restoration, has in some instances increased the water available for hydropower production while reducing flood risk.
Ongoing monitoring is capturing resulting ecological responses such as rejuvenation of native willow-cottonwood forest, suppression of invasive and non-native tamarisk, restoration of more natural densities of beaver dams and associated lotic-lentic habitat, changes in aquatic insect populations, and enhanced groundwater recharge.
Due to very limited available data, innovative approaches were developed for estimating flow needs based on experiences and observations of the local people who depend on this nearly pristine river reach.
However, very few of these are comprehensive and holistic, accounting for seasonal and inter-annual flow variation needed to support the whole range of ecosystem services that healthy rivers provide.
Other tried and tested environmental flow assessment methods include DRIFT (King et al. 2003), which was recently used in the Kishenganga HPP dispute between Pakistan and India at the International Court of Arbitration.
In India, the need for environmental flows has emerged from the hundreds of large dams being planned in the Himalayan rivers for hydro power generation.
There have been some recommendations by various authorities (Courts, Tribunals, Expert Appraisal Committee of the Ministry of Environment and Forests (India)) on releasing e-flows from dams.