LOCATION.--Lat 43° 00'15", long 111°
43'00"(Rev.)(NAD83), in SW1/4 NE1/4 sec.12, T.5 S., R.40 E.,
Caribou County, Hydrologic Unit 17040207, Meadow Creek Mountain
quad., Bureau of Land Management lands, near spillway at left end of
Blackfoot Dam on Blackfoot River, 12 mi northwest of Henry, and at
mile 69.0.
DRAINAGE AREA.--567 mi2, revised.
PERIOD OF RECORD.--January 1912 to September 1925 (gage heights
only), January 1929 to September 1989, May 2011 to October 2012
(discontinued). Prior to 1950, published as "Blackfoot Marsh
Reservoir near Henry".
GAGE.--Water stage recorder. Datum of the gage is National
Geodetic Vertical datum of 1983. Prior to 1990 a non recording gage
read occasionally by U.S. Geological Survey employees and at a gage
datum of 6,100 ft. above National Geodetec Vertical Datum of 1929
(levels by Indian Field Service).
REMARKS.--Water diverted from reservoir for irrigation of about
50,000 acres near Pocatello and on Fort Hall Indian Reservation.
Capacity is 313,000 acre-ft between elevation 6,086 ft, bottom of
outlet tunnel, and 6.118.5 ft, crest of spillway, with provision for
additional storage by water from Grays Lake beginning May 1924.
Storage began in spring of 1910.
EXTREMES FOR PERIOD OF RECORD.--Maximum contents observed, 353,200
acre-ft June 12, 1984, elevation, 6,112.75 ft; minimum observed, 610
acre-ft Sept. 12-15, 19, 21, 22, 1934; minimum elevation observed,
6,088.59 ft Sept. 22, 1934.