1855 -- Yakama Indian Nation treaty with the United States provides the nation with the senior water right to protect fish. Affirmed in court decisions.

1867 -- First recorded diversion of water by non-Indians for irrigation off the reservation in the Lower Naches Valley. By 1902, more than 120,000 acres are being irrigated.

1905 -- Federal Bureau of Reclamation obtains ownership of all surface water not then being used to supply the fledgling Yakima Irrigation Project. The project rights are junior to those of the Yakama Nation and the early settlers, and are reduced when a shortage occurs. The project rights are senior to everyone who came after 1905.

1917 -- State adopts surface water code, creating a permit process for new surface water rights, requiring a finding that water is available and a determination of whether those new rights affect existing rights.

1945 -- State adopts groundwater code that establishes a priority system for obtaining permits for new uses of groundwater, recognizing that groundwater use can affect surface flows.

1977 -- Drought in the Yakima Valley prompts legal disputes among senior and junior water-right holders. The state starts an adjudication of all surface water rights to resolve the disputes, a case still ongoing in Yakima County Superior Court.

1992-2005 -- Five droughts in this time period; court orders all mountain cabins and camps to shut off water in 2001, 2004 and 2005; temporary purchase of senior rights by state Department of Ecology allows water to remain in the stream to offset cabin use.

1993 -- Ecology issues more than 40 new well permits for farmers in the Moxee and Lower Valley areas, prompting appeals by the Yakama Nation. After five years of wrangling, the Yakama Nation settled with 27 applicants, who agreed to pay into a fund for buying water to offset their pumping.

1997 -- The Legislature authorizes the creation of local water conservancy boards to help process applications to change the purpose or place of water use.

1998 -- The National Marine Fisheries Service lists summer steelhead as threatened in the Middle Columbia River, which includes the Yakima River Basin. Bull trout are added a year later.

1999 -- Ecology, the Yakama Nation and the Bureau of Reclamation agree to study the impact of groundwater pumping on surface water. Ecology agrees not to act on applications for new wells until the study is completed. Permit-exempt wells for new homes are excluded.

2007 -- A citizens group, Aqua Permanente, petitions Ecology to prohibit new water wells in Kittitas County. Ecology denies and instead starts to work with the county on how to handle future well requests.

2008 -- Bureau of Reclamation concludes the massive Black Rock storage project would be too costly for the benefits provided.

2009 -- Ecology imposes an unprecedented moratorium on all wells in upper Kittitas County, including permit-exempt domestic wells, as talks with Kittitas County drag on.

2010 -- The U.S. Geological Survey's preliminary results confirm that groundwater pumping intercepts water destined for streams where all water is owned by existing rights. Study estimates that all groundwater pumping reduced flows in the Yakima River at Parker, south of Union Gap, by 115 cubic feet per second as of 2001. The Parker location is key, because a 1994 federal law requires the Bureau to maintain a minimum flow there of at least 300 cubic feet per second. Permit-exempt uses of groundwater account for an estimated 6 cubic feet per second of that amount on an annual basis.

2011 -- Basin water and government interests agree on the outlines of a $5 billion plan to add storage at Bumping Lake and Wymer. The U.S. Geological Survey launches a study of groundwater in upper Kittitas County, an area excluded from the original study.

-- David Lester