Definitions
- af or AF:
Acre foot. The amount of water required to flood one acre one foot deep.
- Confining Layer:
A relatively impermeable underground layer, usually of clay, which restricts vertical movement of groundwater. In Owens Valley, confining layers of clay generally extend from the toes of the alluvial fans along the Sierra Nevada east to the toes of the fans along the White and Inyo Mountains. The Conceptual diagram of the Owens Valley Aquifer (modified from Figure 9-7 ) of the EIR to the LTWA shows a good visualization of confining layers.
- Dispute Resolution:
A procedure for resolving disputes regarding implementation of the LTWA. It is defined in section XXVI. of the LTWA. The MOU to the EIR of the LTWA has its own Dispute Resolution procedure established (Section VI. MOU)
- DWP or LADWP:
Los Angeles Department of Water and Power. The DWP website is at http://www.ladwp.com/ladwp/homepage.jsp
- EIR:
Environmental Impact Report. The California Environmental Quality Act requires that an EIR be written for projects which may significantly impact the environment. After DWP completed the second barrel of the aqueduct in 1970, Inyo County sued under CEQA to force DWP to write an EIR for the groundwater pumping used to fill the expansion of the aqueduct. The first two EIR's were rejected as inadequate by the court. The third EIR, written to cover both the pumping for the aqueduct and the LTWA, was also found to be inadequate. Rather than start all over on a fourth EIR, however, the court invited The Owens Valley Committee, the Range of Light Group of the Sierra Club, the California Department of Fish and Game and the California State Lands Commission to be "friends of the court" and negotiate with DWP and Inyo County an MOU to remedy the deficiencies of the EIR to the LTWA.
- Green Book:
The technical appendix to the LTWA.
The location of each management area, vegetation monitoring site, and each monitoring well; the wells linked to each vegetation monitoring site; the method for locating additional monitoring sites and monitoring wells; the type of monitoring to be conducted at each site; and the standardized procedures for analysis and interpretation of monitoring results, including the determination of available soil water and the amount of soil water required by vegetation, are set forth in a technical document called a "Green Book."
(Section I.E LTWA). The full text of the Green Book is available at http://www.inyowater.org/Water_Resources/Green Book 2000.PDF- Hydrograph:
Graph in which water table depths are plotted over time. Water table depth is usually plotted on the Y (vertical) axis while time is usually plotted on the X (horizontal) axis.
- ICWD:
Inyo County Water Department. The ICWD website is at http://www.inyowater.org
- LTWA:
Inyo-Los Angeles Long Term Water Agreement The full text of the LTWA is available at http://www.inyowater.org/Water_Resources/water_agreement/default.html
- MOU:
Memorandum of Understanding. The LTWA was negotiated in 1990: 1) to settle CEQA litigation initiated in 1972 over deficiencies in the EIR for the pumping to fill the second barrel of the Los Angeles Aqeduct; and 2) to insure future groundwater management would avoid significant environmental impacts while providing a reliable supply of water to Los Angeles. The EIR for the LTWA itself, however, was found to be deficient by the court with jurisdiction over the original CEQA litigation. Rather than throw out the LTWA and start from scratch to resolve the original CEQA litigation, the court invited The Owens Valley Committee, the Range of Light Group of the Sierra Club, the California Department of Fish and Game, and the California State Lands Commission to be "friends of the court" and negotiate with DWP and Inyo County an MOU to remedy the deficiencies of the EIR to the LTWA. After seven years of negotiation, an MOU was signed among these six groups. This 1997 MOU is the one to which references in this website to "the MOU" refer. The full text of the MOU is available at http://www.inyowater.org/Water_Resources/mou/default.html The 1982 MOU under which the Inyo-LA Standing Committee was formed is a different MOU.
- On/Off:
The pumping management protocol in the Green Book is often referred to as "On/Off management". The Green Book contains complicated procedures for determining whether any given well can be pumped (on) or must not be pumped (off). The basic idea is that a pump can be turned on only when there is sufficient soil moisture to support vegetation at the monitoring site associated with the pump. Pumps can be go into On status any time of the year. Pumps can go into Off status only on July 1, or October 1 of any given year. Both ICWD and DWP agree that the On/Off protocol is inadequate to meet the goals of the LTWA. Unfortunately, as of April 2004 neither ICWD nor DWP have proposed an alternative.
- Permanent monitoring site:
Sites where plant cover and species composition, and soil moisture are measured every year. As of March 2004 there are 33 permanent monitoring sites. 22 of the sites are associated with particular wells. Data on soil moisture and plant cover from each monitoring site are used in the on/off protocol to determine whether the wells associated with each monitoring site will be pumped or not. The remaining 11 permanent monitoring sites are in areas not impacted by pumping and are used as controls i.e. for comparisons with those in pumped areas.
- Screened:
The portion of a well that is not sealed off from the surrounding rock is considered to be screened. The screening depth of a well is the depth at which the sealing ends and the well is open to draw in water from the surrounding material. Wells constructed since the 1970's have generally been sealed where they penetrate shallow aquifers and screened only in deep aquifers under confining layers.
- Standing Committee:
The Inyo-LA Standing Committee was formed pursuant to an MOU signed September 2, 1982. DWP representatives on the Standing Committee shall include at least one (1) member of the Los Angeles City Council, the Administrative Officer of the City of Los Angeles, two (2) members of the Board of Water and Power Commissioners, and three (3) staff members.
Inyo County representatives on the Standing Committee shall be at least one (1) member of the Inyo County Board of Supervisors, two (2) Inyo County Water commissioners, and three (3) staff members.
Inyo County shall have one (1) vote and Los Angeles shall have one (1) vote (Section II. LTWA).
