Alkali Flats Warm Spring

Closure notice: Alkali Flats Warm Spring is not open to the public, and no public soak exists there. The spring lies in the Fort Hall Bottoms, within the Fort Hall Indian Reservation of the Shoshone-Bannock Tribes, and the reservation is closed to the general public under tribal law. This page is a documentation and history record, kept so the site’s account of Idaho’s springs is complete and honest. It is not a visitor guide, and there is no trip to plan around this spring.

Alkali Flats is one of the faintest entries in Idaho’s thermal record: a warm spring in the Snake River floodplain that appears in the federal geothermal inventories and almost nowhere else. It has no resort, no operator, no documented pool, and no history as a place anyone traveled to soak. Its whole written life is three federal dataset records and a single water chemistry sampling visit in 1977.

At a Glance

The facts below describe an inventoried, closed spring on tribal land. They are collected here so readers are not misled by the name turning up in federal lists: there is no soak to visit at Alkali Flats.

Current Status & Access

The spring’s township and floodplain setting place it inside the Fort Hall Indian Reservation, in the reach of Snake River floodplain known as the Fort Hall Bottoms: some 25,500 acres of tribal land along the river, administered by the Tribes’ Land Use Policy Commission. The access regime is stated plainly in the Shoshone-Bannock Tribes’ official Trespass Permit: “The Fort Hall Reservation is closed to the general public. Except for Tribal Members and those specifically exempted, no person may trespass on the Fort Hall Reservation.” Entry itself requires a sponsored, purpose-specific tribal permit that covers crossing only.

The one recreation the Tribes sell to non-members in the Bottoms is limited fishing, under a capped tribal permit program for the Bottoms’ spring creeks and the Snake River. No soaking, swimming, or general visiting use is offered anywhere on the reservation. This closure is jurisdictional rather than seasonal: it does not lift at any time of year, and there is no agency office, permit, or access point that turns this spring into a destination. Please respect the Tribes’ law and land, and do not attempt to reach the spring.

Location & Place Information

Alkali Flats Warm Spring rises in the Snake River floodplain in Bingham County, in the wetland country at the head of the American Falls Reservoir reach, where groundwater springs feed the spring creeks and marshes of the Fort Hall Bottoms. Because the spring sits on closed tribal land, this listing gives the county and the landscape only: there is no street address, no public access point, and no directions. The nearest town is Blackfoot, the Bingham County seat, roughly 20 miles northwest. The land-side authority for the area is the Shoshone-Bannock Tribes, who publish no page for this spring.

The Spring Itself

The one firm physical fact is the temperature. The USGS thermal springs list gives 93°F, the federal GEOTHERM database gives 34°C, and NOAA-derived thermal data gives 93°F again, so the inventories agree: this is a warm spring, not a hot one, and the “Warm Spring” in its inventory name is accurate. Federal surveyors visited once for a closer look: on August 18, 1977, the USGS sampled the water for a full major-ion chemistry suite, and that sampling site remains part of its federal record.

Beyond that, the record is silent. No flow measurement exists, no source describes the spring’s physical form, and no pool, tub, or soaking opportunity has been documented at Alkali Flats at any date. The Bottoms’ springs collectively matter a great deal, feeding the spring creeks behind the area’s well-known tribal trout fishery, but this spring’s own contribution has never been separately described.

History of Alkali Flats Warm Spring

Alkali Flats enters the written record through the twentieth century federal geothermal inventories. It is carried in the USGS thermal springs list in the lineage of the early national surveys, at 93°F on the Yandell Springs quadrangle. It appears in the GEOTHERM database as record 0081048, compiled in USGS Open-File Report 83-431 with data current to December 1981. And it was sampled once by the USGS for water chemistry, on August 18, 1977. That is the whole of its documented history.

The land around it was mapped early because of the reservation itself. Mansfield’s USGS Bulletin 713, “Geography, geology, and mineral resources of the Fort Hall Indian Reservation” (1920), surveyed the reservation’s townships, and it is the survey behind the federal geographic records that place this spring’s township inside the reservation. The bulletin is context for the land; it does not name or describe this spring.

Nothing else is recorded. No source explains the spring’s name, documents a structure, a resort era, or any historic use, and this page will not invent one. The Fort Hall Bottoms are a culturally and ecologically significant tribal landscape, and that significance is a reason for this listing’s restraint: what can honestly be said about Alkali Flats is that the spring is real, that the federal inventories have carried it for a century, and that it lies on tribal land where it is not the public’s to visit.

Fees, Hours & Reservations

There are none. Alkali Flats Warm Spring is not an attraction, takes no visitors, and has no hours, fees, or reservations. Questions about access to the Fort Hall Reservation belong to the Shoshone-Bannock Tribes.

Nearby Hot Springs

There is no soak at Alkali Flats, and none on the reservation. For springs in the same corner of the state that can actually be visited, see the region’s listings: South-East Idaho hot springs →