Critical Groundwater Areas Overview
IDWR’s Director is granted the authority to designate Critical Groundwater Areas (CGWAs) under Idaho Code Title 42, Chapter 233a. This section codifies the definition and bases for designating CGWAs.
A CGWA is all or part of a groundwater basin that does not have sufficient groundwater to provide a reasonably-safe supply for irrigation or other uses at the current or projected rates of withdrawal. IDWR’s Director can deny an application for a proposed use if the point of diversion lies within the designated area, and the Directory may require water users to report diversions or other information.
Designated Critical Groundwater Areas
Listed below are Idaho’s designated CGWAs. Click the area name for the description as well as orders and related publications.
| Area | Date Designated | Map | Hydrographs |
|---|---|---|---|
The Blue Gulch CGWA, located in eastern Owyhee and western Twin Falls counties, was declared on December 9, 1970. This declaration was based on a report by Chapman and Ralston (February 1970) which stated that discharge was exceeding recharge. At the time, the area was being considered for increased agricultural development through the federal Desert Land Entry program which would have increased groundwater diversions for irrigation. Outstanding water appropriation permits were anticipated to divert over four times the usage. Designation as a CGWA stopped the processing of new applications while allowing the development of existing permits. A management plan has not been developed nor has an advisory committee been formed. Orders
Related Publications
| December 9, 1970 | Map | Hydrographs |
The Cinder Cone Butte area, located in Elmore County, was declared a CGWA on May 7, 1981 because of declining groundwater levels. Following the declaration, a study was conducted to evaluate the entire Mountain Home area. As a result of that study, the Mountain Home GWMA (which surrounds the Cinder Cone Butte area) was designated on November 9, 1982. New groundwater appropriations are not allowed in the Cinder Cone Butte CGWA. For related information, visit the Mountain Home GWMA page. | May 7, 1981 | Map | Hydrographs |
Curlew Valley is located in southeastern Idaho in Oneida and Power counties and extends south into Utah. The Curlew Valley CGWA was designated on March 15, 1976, and was based on concern that there was not sufficient groundwater supply for existing irrigation uses or to fulfill pending applications and permits. The geographic and hydrogeologic boundaries extend into Utah. In the southern part of the basin, Locomotive Springs is an area of discharge for the aquifer and a Utah state wildlife management area. The State of Utah expressed concern that increased groundwater withdrawals in Idaho were impacting the spring flows. No further studies have been conducted since designation of the CGWA to determine adequacy of supply or impacts on spring flows. A management plan has not been developed for the area nor has an advisory committee been formed. Orders
Related Publications
| March 15, 1976 | Map | Hydrographs |
The Oakley Fan is located in northeastern Twin Falls and western Cassia Counties. Originally declared as the Goose Creek-Rock Creek CGWA on January 16, 1962, the boundaries were modified on September 6, 1967, creating three separate CGWAs: Artesian City, Cottonwood, and Oakley-Kenyon. On January 19, 1982, the West Oakley Fan CGWA was established. The four areas create a contiguous tract and have been managed as a single unit. The order modifying the boundaries and establishing the initial three areas stated "there does not appear to be available unappropriated groundwater within the boundaries of the three designated areas. Therefore, new appropriations of water shall not be allowed." The West Oakley Fan order did not specifically prohibit new diversions. However, the order stated that a study indicated that the available groundwater was limited. A management plan has not been developed nor has an advisory committee been formed. A groundwater recharge demonstration project has been ongoing in the region since the early 1990s. However, only limited volumes have been recharged. Orders
Related Publications
| January 16, 1962 | Map | Hydrographs |
The Oakley Fan is located in northeastern Twin Falls and western Cassia Counties. Originally declared as the Goose Creek-Rock Creek CGWA on January 16, 1962, the boundaries were modified on September 6, 1967, creating three separate CGWAs: Artesian City, Cottonwood, and Oakley-Kenyon. On January 19, 1982, the West Oakley Fan CGWA was established. The four areas create a contiguous tract and have been managed as a single unit. The order modifying the boundaries and establishing the initial three areas stated "there does not appear to be available unappropriated groundwater within the boundaries of the three designated areas. Therefore, new appropriations of water shall not be allowed." The West Oakley Fan order did not specifically prohibit new diversions. However, the order stated that a study indicated that the available groundwater was limited. A management plan has not been developed nor has an advisory committee been formed. A groundwater recharge demonstration project has been ongoing in the region since the early 1990s. However, only limited volumes have been recharged. Orders
Related Publications
| January 16, 1962 | Map | Hydrographs |
The Oakley Fan is located in northeastern Twin Falls and western Cassia Counties. Originally declared as the Goose Creek-Rock Creek CGWA on January 16, 1962, the boundaries were modified on September 6, 1967, creating three separate CGWAs: Artesian City, Cottonwood, and Oakley-Kenyon. On January 19, 1982, the West Oakley Fan CGWA was established. The four areas create a contiguous tract and have been managed as a single unit. The order modifying the boundaries and establishing the initial three areas stated "there does not appear to be available unappropriated groundwater within the boundaries of the three designated areas. Therefore, new appropriations of water shall not be allowed." The West Oakley Fan order did not specifically prohibit new diversions. However, the order stated that a study indicated that the available groundwater was limited. A management plan has not been developed nor has an advisory committee been formed. A groundwater recharge demonstration project has been ongoing in the region since the early 1990s. However, only limited volumes have been recharged. Orders
Related Publications
| January 16, 1962 | Map | Hydrographs |
The Oakley Fan is located in northeastern Twin Falls and western Cassia Counties. Originally declared as the Goose Creek-Rock Creek CGWA on January 16, 1962, the boundaries were modified on September 6, 1967, creating three separate CGWAs: Artesian City, Cottonwood, and Oakley-Kenyon. On January 19, 1982, the West Oakley Fan CGWA was established. The four areas create a contiguous tract and have been managed as a single unit. The order modifying the boundaries and establishing the initial three areas stated "there does not appear to be available unappropriated groundwater within the boundaries of the three designated areas. Therefore, new appropriations of water shall not be allowed." The West Oakley Fan order did not specifically prohibit new diversions. However, the order stated that a study indicated that the available groundwater was limited. A management plan has not been developed nor has an advisory committee been formed. A groundwater recharge demonstration project has been ongoing in the region since the early 1990s. However, only limited volumes have been recharged. Orders
Related Publications
| January 19, 1982 | Map | Hydrographs |
The Raft River CGWA, located in Cassia County of south-central Idaho, was originally designated on July 23, 1963. Subsequent orders modified the boundaries: eliminating an area on the extreme northern boundary (August 2, 1965); the Albion basin (September 19, 1966); the area north of the Yale-Cotteral Road (November 3, 1970); and, the upper Raft River Valley, Elba, and Yost-Almo subbasins (June 30, 1977). Large-scale groundwater pumping in the Raft River valley began in 1950 and increased through the 1950s. USGS documented declining water levels and decreased stream flow in the Raft River from 1956 through 1960. By 1963, concern over the potential effects of new and increased groundwater use caused the designation as a CGWA. Creation of the management area did not include formation of advisory committee or development of a management plan. Orders
Related Publications
| July 23, 1963 | Map | Hydrographs |
Map of Critical Groundwater Areas
Use the map below to find the designated Critical Groundwater Area boundaries. Need a larger map? Click here to view a full-size interactive map of the Critical Groundwater Areas and Groundwater Management Areas.
<iframe width="100%" height="800" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" title="Groundwater Management Areas" src="https://maps.idwr.idaho.gov/agol/CriticalGroundwaterAreas/"></iframe>
Expansion Rights in CGWAs
An expansion right is an expanded use of a groundwater right located within a CGWA where the expanded use occurred after the designation of the CGWA and is in violation of mandatory permit requirements. Groundwater is deemed to be unavailable to fill expansion rights unless a management program exists which will, within a time period acceptable to the director of IDWR, limit average annual water withdrawals from the aquifer designated in the CGWA to no more than the average annual recharge to the aquifer. Expansion rights may be curtailed if the director of IDWR determines that an adequate management program does not exist within two years after the completion of a general adjudication.
A number of CGWA expansion rights were decreed within the Oakley Fan and Raft River CGWAs as part of the Snake River Basin Adjudication (SRBA). The SRBA was completed as of August 25, 2014. IDWR will provide notice to the holders of CGWA expansion rights about the requirements of Idaho Code § 42-1416B.
Oakley Fan Expansion Rights - Archived Records
- Final Order Re: Management Program in the Oakley Fan Critical Groundwater Area – August 26, 2016
- Final Order Regarding Management Program in the Cottonwood Critical Groundwater Area – August 26, 2016
- Southwest Irrigation District/Goose Creek GWD CGWA Management Plan – August 22, 2016
- Southwest Irrigation District/Goose Creek GWD CGWA Management Plan – June 15, 2016
- Deadline for Submittal of Management Program in Oakley Fan CGWAs
- Presentation on Expansion Water Rights in the Oakley Fan Critical Groundwater Areas – February 5, 2015
- Notice of Public Information Meeting on February 5, 2015
- List of Expansion Rights in Oakley Fan CGWAs – August 23, 2016
- Map of Oakley Fan CGWAs and Expansion Rights
Raft River Expansion Rights - Archived Records
- Amended Final Order Re: Management Program and Curtailing Expansion Rights in the Raft River Critical Groundwater Area – September 21, 2016
- Petition for Reconsideration of Final Order Regarding Management Program and Curtailing Expansion Groundwater Rights in the Raft River Critical Groundwater Area – September 6, 2016
- Final Order Re: Management Program and Curtailing Expansion Rights in the Raft River Critical Groundwater Area – August 26, 2016
- Raft River Groundwater District CGWA Management Plan – June 15, 2016
- Deadline for Submittal of Management Program in Raft River CGWA
- Presentation on Expansion Water Rights in the Raft River Critical Groundwater Areas – February 18, 2015
- Notice of Public Information Meeting on February 18, 2015
- List of Expansion Rights in Raft River CGWA – August 26, 2016
- Map of Raft River CGWAs and Expansion of Ground Water Rights – January 16, 2015