dams

The dams retain enough water to aquify the surrounding land but do not completely restrict the flow.

With dams holding back two years of water flow surely you are in a position to do the same.

But, also environmental diversion often counts water several times as the same water passes several dams.

This becomes impractical for the largest rivers, but larger rivers often have a network of dams to achieve the same effect.

There are many small dams that really are obsolete or of little benefit, but Sierra Club also opposes some that have clearer benefits.

Unlike people at the dawn of civilization, those farmers didn't build those dams on the Colorado River, the Army Corps of Engineers did.

Then you enter an arms race by building levys/dams/dikes and we're still just treating the symptoms.

Further, people want large changes like dams to reduce flooding, drainage etc.

They can open or close hydroelectric dams, causing flooding and death.

Big game is rare, no wolves, a handful of bears, few to no birds, orders of magnitude less fish due to dams.

We built dams all over the rivers feeding it.

A record-setting 72 dams were removed across 19 states...

Wikipedia gives some 908 notable dams, and 137 hydroelectric facilities of 1GW+ net capcity.) There are other questions, notably whether or not "deaths per GWh generation" is the most appropriate measure of risk.

Dams and canals aren't just subsides, they're system efficiency multipliers, much like the Interstate Highway system.