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Records of GASP

Identifier: WGAS

Scope and Contents

The Records of GASP consists of documents dated 1912 to 2007, with the bulk falling from 1970 to 2007. The collection includes agreements for water rentals and transfers obtained by the company to replace depletions caused by wells, as well as yearly plans of operation indicating how this water was used to allow pumping within Colorado's administrative framework. Also of interest are board meeting minutes and agendas, correspondence with the State Engineer's office, extensive membership lists, and information about individual wells. Oversize maps detail reservoirs, irrigation networks, and streamflows along the Front Range. Several legal cases and related correspondence pertinent to well-augmentation are included. Additionally, GASP's filings for a substitute supply plan in 2003 detail the company's growing difficulties in sustaining its operations in the face of legal and administrative changes. Predominant material types include operation plans, membership lists, well information, legal documents, dissolution documents, marketing materials, correspondence, meeting minutes and agendas, as well as oversize maps and drawings.


  • Creation: 1912-2007
  • Creation: Majority of material found within 1970-2007


Restrictions on Access

There are no access restrictions on this collection. However, some items are stored off-site, so advance notice is recommended.

Restrictions on Use

Not all of the material in the collection is in the public domain. Researchers are responsible for addressing copyright issues.


The Groundwater Appropriators of the South Platte River Basin, Inc. (GASP) was a non-profit well-augmentation company, the first of its kind in Colorado. Founded in 1972, its purpose was to offset depletions to the South Platte River caused by extensive pumping of the South Platte valley-fill aquifer, which is hydrologically connected to the flowing stream. By supplying replacement water to the river and its adjoining aquifer, the company's operations enabled thousands of wells to utilize groundwater, despite their junior status relative to most surface rights within Colorado's prior appropriation system. At its peak, GASP served more than 3,000 wells in northeastern Colorado. However, as state regulations of this activity were modified in 2001 and the state experienced severe drought in 2002, the company ceased operations, selling the last of its assets in 2007.

Use of groundwater in Colorado dates back to at least the 1880s, but its development mushroomed after World War II, when technological improvements and low-cost electric power encouraged well-drilling for commercial irrigation. This activity spread throughout the state and became especially popular in the South Platte valley, where a shallow aquifer composed of loose gravel and sediments made pumping both productive and economical. Periodic drought, coupled with advances in pumping and drilling technology, further encouraged the use of wells as an alternative to surface water supplies. In some areas, especially where surface flows were intermittent, irrigators came to rely exclusively on underground water for their enterprises. Despite concerns that pumping could diminish local water tables and ultimately impair surface-water rights by affecting the flow of the South Platte River, development proceeded virtually unregulated for decades.

GASP was created in response to Colorado's 1969 Water Rights Determination and Administration Act, which sought to regulate most types of groundwater use conjunctively with surface-water rights under the state's established doctrine of prior appropriation. This system, in which older claims are entitled to their full share of water before newer claims can be fulfilled, threatened to shut down most wells in the South Platte River valley if strictly applied - wells were liable to be curtailed when senior surface users needed more water to satisfy their claims. To avoid this outcome, lawmakers included provisions in the 1969 Act such as augmentation plans and substitute-supply plans that enabled well users to replace some of the water they withdrew, allowing for continued operation of wells while also protecting surface rights. GASP was the largest among several organizations created to fill this need.

GASP provided replacement water using several methods, including recharge ponds, which allowed surplus water to seep into the aquifer and eventually back to the river; direct wells, which added water to the river at strategic points to satisfy senior rights; and permanent reservoir or ditch company rights, which GASP bought and delivered directly to the South Platte. These water rights, some leased and others owned by GASP, were turned over each year to the State Engineer, who approved the company's replacement plans on a year-to-year basis. GASP members, well-users who paid annual fees, were then allowed to pump out-of-priority, their "debt" to the river and senior surface rights having been satisfied in advance.

GASP's approach to well augmentation became unworkable following a 2001 court ruling and the onset of drought the following year. Since 1972, GASP's replacement plans were reviewed and approved annually by the State Engineer, rather than permanently by a water court. In 2001, the Colorado Supreme Court ruled that the State Engineer lacked proper authority to approve these substitute water supply plans. The next year, Colorado experienced severe drought, which increased well augmentation requirements and simultaneously reduced the availability of annually leased water. Faced with diminished supplies, large obligations, and no immediate avenue to secure legal approval for its plans, GASP ceased operations and sold the last of its assets in 2007.


30.5 linear feet (20 record cartons, 1 flat file, 2 tubes)

Language of Materials



The Groundwater Appropriators of the South Platte River Basin, Inc. (GASP) was a non-profit well-augmentation company, the first organization of its kind in Colorado. Founded in 1972, its purpose was to offset depletions to the South Platte River caused by pumping of the South Platte valley-fill aquifer. At its peak, GASP served more than 3,000 wells in northeastern Colorado. As state regulation of this activity was modified, the company ceased operations in 2003 and sold the last of its assets in 2007. Collection materials include operation plans, membership lists, well information, legal documents, marketing materials, correspondence, dissolution documents, meeting minutes and agendas, as well as oversize maps and drawings. A portion of the collection is digitized and online.


The collection consists of 4 series in 20 boxes, 2 oversize folders, and 2 tubes:

Series 1: Operations, 1943, 1972-2007 and undated

Series 2: Membership, 1970-1998 and undated

Series 3: Printed materials, 1978-1998

Series 4: Oversize, 1912-1999 and undated


The Records of GASP were donated to the Water Resources Archive by Dave King of GASP in three installments, the first in November 2006, the second in March 2007, and the third in July 2009.

Online Materials

Some files have been scanned and are available through the Colorado State University Libraries website. In the electronic version of this document, direct links appear in context.

Related Collections

The Groundwater Data Collection, Water Resources Archive, contains additional information about the development of groundwater use in the South Platte valley and throughout the state, in addition to materials related to augmentation and recharge programs.


Processing of the initial portions of this collection was completed in May 2007. This involved removing metal fasteners, rubber bands and binders; plastic clips were used where needed. Folded documents were unfolded, and acid-free paper was inserted on either side of acidic documents. Large membership binders were left intact and stored flat in boxes, and all materials were rehoused in acid-free containers. Rolled and some folded oversized items were prepared for storage in flat files or in tubes if extra-large. Original order and grouping of material types were maintained wherever possible, and loose documents were filed with similar materials. Exact duplicates beyond two copies were removed, as were blank forms and commonly available publications. Processing of the final part was completed in December 2009. Documents both in folders and in binders were rehoused in acid-free folders and boxes. This portion is found in boxes 18 through 20, but is integrated in the inventory below.

Inventory Note

Note: Title information supplied by the archivist is bracketed. Estimated pagination is preceded by an "e." Authored articles are listed in bibliographic form.

Guide to the Records of GASP
Edited Full Draft
Prepared by Nicolai Kryloff; revised by Jana Leighton
Copyright 2009
Language of description
Script of description
Language of description note
Finding aid written in English.

Repository Details

Part of the CSU Libraries Archives & Special Collections Repository

Fort Collins Colorado 80523-1019 USA