Effects of Irrigation on Salmon

Long before the Hell’s Canyon Complex was constructed, large areas in the Upper Snake were removed from salmon production by early irrigation development. One Corps of Engineers biologist explained that this process was well underway by 1910, and that

“Large irrigation storage dams completely blocked fish migration and diverted water from river channels leaving them with insufficient flow or altering water temperatures adversely for fish many miles downstream from the dam. . . the major source of damage here was the hundreds of unscreened irrigation canals that diverted millions of juvenile salmon and steelhead to die in the farmers’ fields for periods as long as three and four decades.”21

Along the upper Snake River in Idaho, the U.S. Fish and Wildlife Service estimates that eighty percent of the habitat has been lost.22

It does not seem likely that the reduction in flow from river irrigation has itself had any great adverse effect on salmon downriver. In 1990, the total amount of water withdrawn for irrigation in the Pacific Northwest was only about 7% of the average annual flow of the Columbia River.23 There are localized adverse effects from irrigation withdrawals in the Snake River, where Idaho state policy was and is to reduce the River’s flow to zero at Milner Dam. Keith Higginson, the Director of the Idaho Department of Water Resources, said in 1988: “we do not require, expect, need or want any flow to pass Milner.”24

Counting tributaries, there is almost 13.5 million acre-feet of storage capacity in the Snake River Basin.25 Irrigators probably remove 7-8 million acre feet of water from the Snake River every year.26 But since the Hell’s Canyon Complex stopped the salmon from going upstream anyway, it is hard to assess the adverse impact of irrigation.

The biggest problem with irrigation is a problem of governance: since state and federal governments have been incapable of providing clear and reliable property rights in water, irrigators are unable to sell or lease excess water for experiments in fishery management.27 The government has a simple answer: to shut down any future water withdrawals from the Columbia or Snake Rivers. The proposed Snake River Salmon Recovery Plan calls for such a moratorium to extend to "tributaries and those groundwater resources that are part of the Snake and Columbia River System".28

In May 1997, the National Marine Fisheries Service even declared that a single Oregon irrigator’s application to remove 303 cubic feet of water per second (peak) from the John Day pool would jeopardize the continued existence of Snake River salmon.29 All the irrigators together in Oregon take less than 1% of Columbia River flow—even in a low flow year.30 No one really believes that a single irrigation withdrawal will spell the death knell of the salmon, but no single farmer can afford to invest the effort to try and persuade a court that this is not true.

21 Ed Mains, quoted in O. Bullard, Crisis on the Columbia 111.

22 T. Palmer, The Snake River: Window to the West 13 (Island Press 1991).

23 NRC, Upstream at 61 (Prepub. ed.).

24 Quoted in T. Palmer, The Snake River 142.

25 T. Palmer, The Snake River 54 (citing Northwest Power Planning Council study).

26 T. Palmer, The Snake River 103 (1987 figures from the Idaho Department of Water Resources show 8.2 maf consumption).

27 T. Palmer, The Snake River 131.

28 NMFS, Draft Snake River Salmon Recovery Plan, at 70. NMFS refuses to release the draft to the public, although it is circulating to State and Tribal fishery agencies and the Northwest Power Planning Council's Independent Science Advisory Board as this book goes to press in October 1997. The citation comes from some pages of the plan that were anonymously faxed to the Columbia River Alliance.

29 NMFS, Endangered Species Act Section 7 Consultation, Inland Land, Inc., May 16, 1997.

30 Fred Ziari (pers. comm.)

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