Protecting Public Health and the Environment.

Ballard, Henry, and Enoch Mines

Investigations & Remediation Efforts

The US Environmental Protection Agency (EPA) in cooperation with federal, state, and Tribal agencies, proposes to work with the community on a Remedial Investigation/Feasibility Study (RI/FS) and subsequent cleanup (or Remedial Action) at three mine sites: the Ballard, Enoch Valley, and Henry Mine Sites, or P4 Mines. The RI/FS and cleanup will be done under the federal Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). EPA is the lead agency for this effort with DEQ, US Department of Interior, Bureau of Land Management, US Department of Agriculture, US Forest Service, US Fish and Wildlife Service, and the Shoshone-Bannock Tribes participating as support agencies.

Source: EPA website on Southeast Idaho Mines

2009 Cleanup Agreement

In December 2009, an agreement was reached between P4 Production LLC, a southeastern Idaho phosphate mining company, and five federal and state agencies, as well as the Shoshone-Bannock Tribes, to develop comprehensive cleanup plans for three phosphate mines near Soda Springs.The agreement requires P4 Production (a subsidiary of the Monsanto Company) to complete RI/FSs for the Ballard, Henry, and Enoch Valley mines. The Ballard Mine was operated from 1951 to 1969, the Henry Mine was operated from 1969 to 1989, and Enoch Valley Mine was operated from 1989 until recently. They are all currently inactive.

Data already collected by P4 show that selenium and other pollutants are being released from waste rock dumps and contaminating nearby soil, water, and vegetation. EPA will use this and other information captured about the site to develop proposed plans of how to clean them up. EPA will seek formal comment on proposed cleanup plans from interested parties before making final decisions. The first proposed cleanup plan is expected to be completed in the next 2 to 3 years.

Community Involvement Plan

In July 2010, a Community Involvement Plan was developed describing how EPA, in cooperation with federal, state, and Tribal agencies, proposes to work with the community on an RI/FS and subsequent cleanup at the sites, which will be done under the federal CERCLA.

EPA is the lead agency for this effort with support from DEQ, US Department of Interior, Bureau of Land Management, US Department of Agriculture, Forest Service, US Fish and Wildlife Service, and the Shoshone-Bannock Tribes. Identified in the plan are outreach activities the agencies will use to address stakeholder concerns and inform the public about this work and opportunities they will have to provide input during the cleanup process.

History of Ballard Mine

The Ballard Mine is located about 12 miles north of Soda Springs. The first recorded phosphate-related activity in the area of the mine occurred in 1912 when a US Geological Survey (USGS) field party under the direction of R.W. Richards explored the phosphate in the area of the future Ballard Mine with two hand-dug trenches.

There was no further interest in the phosphate deposits of this area until the J. R. Simplot Processing Company (later the J. R. Simplot Company) filed an application to lease the phosphate from the federal government on August 28, 1947. A lease sale was held on July 21, 1948. There were two bidders in the sale, the J. R. Simplot Company and the Washington Cooperative Farmers Association. The Simplot Company was the successful high bidder and was issued lease BL-055875 on December 1, 1948. The Simplot Company’s intentions were to mine the lower grade phosphatic shales to feed an electric furnace to make elemental phosphorus. The Simplot lease was the first lease ever issued by the federal government in which development of lower grade ores specifically was the intent (Salt Lake City Tribune, Thursday, December 9, 1948). Simplot never developed the lease for either low-grade or high-grade ore and on May 23, 1951, the Simplot Company assigned the lease to the Monsanto Chemical Company. Monsanto began exploration activities on July 16, 1951.

Exploration in 1954 in the area of the mine and development of the ore body within the existing lease showed that a large volume of ore existed outside of lease BL-055875. On February 7, 1955, Monsanto applied to lease that ore with the Bureau of Land Management (BLM). Lease I-05723 was issued to the Monsanto Company on July 1, 1955. Once that ore had been secured, the West Ballard Pit was developed on the new lease. The West Ballard Pit contained the largest ore reserves and was operated longer than any of the other pits in the mine. The Ballard Mine eventually consisted of several side-hill, open-pit excavations.

Mining continued in various places on the two leases until late 1969 when the Ballard Mine was finally worked out entirely. Even before the mine was worked out, reclamation had started on the earlier pits. As early as 1958, the Ballard Mine dumps were used for experimental plantings for reclamation. Additional experimental plantings were done in the 1960s, and in the early 1970s, the US Forest Service Experimental Station at Logan, Utah, planted a total of 78 types of trees, shrubs, grasses, and forb seeds and seedlings and cuttings on the dumps (USGS 1977). These experimental reclamation plantings had varying degrees of success.

In 1970, the Monsanto Company completed active mining at the Ballard Mine. During the 18 years of production, about 11 million tons of phosphate rock were mined and removed from about 191 acres at the Ballard Mine on the two federal leases. Over 20 million cubic yards of waste rock were stripped; of this amount, 2 million cubic yards were used to backfill the pits with the remaining 18 million cubic yards hauled to the dumps. About 317 acres of land were covered by the dumps and an additional 96 acres were used as service areas for the mine (USGS 1977).

The Monsanto Company filed relinquishments for the two federal leases on April 30, 1984. The BLM accepted the relinquishments and the leases were closed on July 3, 1984.

Source: A History of Phosphate Mining in Southeastern Idaho, William H. Lee, 2000.

History of Henry Mine

The Henry Mine, operated by the Monsanto Company, is located southeast of the small village of Henry, Idaho. The phosphate resources in the area of the North Pit of the Henry Mine were first explored in 1912 by a field party of the USGS.

There was no further known interest in the phosphate of this particular area until the Monsanto Chemical Company applied to the BLM for a federal phosphate lease on March 15, 1960. A phosphate lease sale was held on July 7, 1960. There were two bidders at the sale, the J. A. Terteling and Sons Company and the Monsanto Chemical Company. Monsanto was the high bidder and was issued federal lease I-011451 on September 1, 1960. Monsanto’s intent was to use the ore on this lease as replacement for the dwindling resources at its Ballard Mine (Carter 1978).

Exploration on its newly acquired federal lease soon led the Monsanto Company to seek additional adjacent acreage. On December 10, 1962, Monsanto applied to the BLM for a prospecting permit covering land immediately south of federal lease I-011451. The BLM issued a prospecting permit on April 5, 1963. Apparently, Monsanto found phosphate ore in the area of the permit because it filed an application with the BLM for a Federal Preference Right Lease on January 11, 1965. The lease, I-013814, was issued on December 1, 1965.

Mining at the Henry Mine began in 1969. Mining in the South Henry Pit (Pit III) started in the fall of 1976. Mining operations in that pit were completed in 1980, and mining then started in the Center Henry Pit (Pit IV) in the summer of 1981. Mining in the Center Henry Pit was completed in the fall of 1985. The North Henry Pit (Pit V) was opened, and mining operations started at the beginning of the summer mining season in 1986.  Mining operations were completed at North Henry in mid-October 1989, bringing to a close the active phase of the Henry Mine.

Reclamation of the Henry Mine progressed throughout the active mining phase with excavated waste rock being used to backfill the pits as mining advanced. Once the mine closed in late 1989, other forms of reclamation took place such as reseeding and hydromulching of the highwalls. Reclamation continued for a number of years after mining and monitoring of the reclamation effort continued even longer.

Monsanto applied to the BLM for relinquishment of the two federal leases on December 3, 1993. The BLM accepted the relinquishments on December 7, 1993, and the leases were closed, thus bringing an end to the Henry Mine.

Source: A History of Phosphate Mining in Southeastern Idaho, William H. Lee, 2000.

History of Enoch Valley Mine

The Enoch Valley Mine is located in Caribou County, Idaho. The mine lies about 19 air miles northeast of Soda Springs. Mining is conducted on three federal phosphate leases and two state of Idaho phosphate leases. The presence of phosphate ore in this area has been known since the early 1900s. There was some very early exploration for phosphate ore in the immediate vicinity of the future Enoch Valley Mine. The USGS explored this area in 1912 and reported earlier prospect pits by unknown prospectors. 

A flurry of phosphate lease applications were filed with the BLM in 1947 for the phosphate resources in the area of the future mine. None of the lease applications wereissued for a variety of administrative reasons, mostly lack of controlling regulations and failure to submit a filing fee, but that activity indicated interest in the resource in this area.

No further phosphate interest or exploration was reported in the vicinity of the future Enoch Valley Mine until the USGS revisited the area in 1949. 

The BLM held a lease sale on June 4, 1964, for that tract of land. There were four bidders at the sale: FMC Corporation, Monsanto Chemical Company, Phyliss E. Colman, and J. A. Terteling and Sons. The FMC Corporation was the high bidder and was awarded the lease, I-015122, on September 1, 1964. The FMC Corporation began exploration immediately after the lease award. Under an agreement with FMC, Monsanto did some exploration drilling of its own on lease I-015122 between 1972 and 1980. Monsanto Company also applied for state lease E-07957 on February 16, 1978. The state of Idaho awarded the company that lease on May 1, 1978. It became apparent to the Monsanto Company that the phosphate resource on its new leases could not be fully developed without some additional adjacent state-owned land, so it acquired state lease E-08379 on April 2, 1981.

The Monsanto Company began to develop its leaseholds in preparation for mining in late 1987. The company’s operation at the Henry Mine was winding down, and a source of future ore needed to be developed. The initial pit mining began on October 10, 1989. Actual shipment of ore from the new Enoch Valley Mine began in the spring of 1990, with the first production shipment from federal lease I-015122 and state of Idaho lease E-07957 in May. The ore from the mine was to feed Monsanto’s elemental phosphorus plant near Soda Springs.

On September 1, 1997, Monsanto spun off its traditional chemical business to form Solutia. Monsanto retained its pharmaceutical, foods, biotech, agricultural chemicals, and seeds business. On that same day, Solutia and Monsanto formed a joint venture called P4 Production L.L.C., organized under the laws of the state of Delaware. The phosphate leases were assigned to P4 Production. P4 Production also owns, to the current time, the Soda Springs elemental phosphorous plant and all other mineral rights formerly held by Monsanto. Operation of the joint venture was originally with Solutia was transferred to Monsanto in June 2000.

Source: A History of Phosphate Mining in Southeastern Idaho, William H. Lee, 2000.

Staff Contacts

Mining Project Coordinator
Michael Rowe
DEQ Pocatello Regional Office
444 Hospital Way #300
Pocatello, ID 83201
(208) 236-6160

DEQ Resources

Area Wide Human Health Ecology Risk Assessment Work Plan 2002 

Community Involvement Plan

More Information

Final Remedial Investigation Report (November 3, 2014)

Administrative Settlement Agreement and Order on Consent/Consent Order (November 6, 2009)

Other Information

History of Phosphate Mining in Southeastern Idaho (William H. Lee, 2000)


Related Pages

Southeast Idaho Phosphate Mining

Selenium Investigations in Southeast Idaho

Conda/Woodall Mountain Mine Site

Georgetown Canyon Mine