However the system is somewhat healthy for the environment. Hydropower fights climate change because it only slightly increases greenhouse gas emissions. Hydroelectric dams account for 4% of total human greenhouse gas emissions. This 4% consists mostly of methane which, although it traps heat much more than carbon dioxide, declines in the atmosphere much faster than carbon dioxide. Hydro also offers potable water storage. Even if farms initially see a decrease in production due to the scarcity of water in the soil, hydroelectric sources solve these problems by offering irrigation systems. The basins of hydroelectric power plants collect rainwater, which can then be used for consumption or irrigation. By storing this water, it protects aquifers from depletion and reduces our vulnerability to drought. (Itaipu.gov, 2014) these irrigation systems turn one of the main disadvantages of dams into a neutral one, suggesting that all farms receive enough water than they received previously. Hydroelectric energy sources have been modified over the years to both increase production and limit the amount of damage it causes to the ecosystem. To address the problem with fish being affected by dams, there have been several alternative routes for salmon to cross the dams. The salmon run is the time when salmon, which have migrated from the ocean, swim upward