"Little Blalock Island" is 0.7 miles long and located 0.3 miles west of Big Blalock Island and 0.8 miles north of Sand Island. The U.S. Board of Geographic Names made "Little Blalock Island" the official name in 1983.

"Sand Island" is 0.2 miles long and is located 0.8 miles south of Little Blalock Island and 2 miles west-southwest of Big Blalock Island. This island is the downstream-most of the islands. The U.S. Board of Geographic Names made "Sand Island" the official name in 1983.

"Rock Island" is 1/4 miles long and is located 0.3 miles southeast of Little Blalock Island and 0.2 miles southwest of Big Blalock Island. This webauthor could not find this island listed on "Topozone.com"'s map (2007). The U.S. Board of Geographic Names made "Rock Island" the official name in 1983.

"Telegraph Island" is another island in the area located north of Little Blalock and Big Blalock Islands, and was not a part of the original Blalock Island. It appears as an unnamed island on the 1906 "Block Island" topographic map. The U.S. Board of Geographic Names made "Telegraph Island" the official name in 1966. Previous variations on the name were "Telephone Island".

"Long Walk Island" is on the Oregon side of the Columbia River located between RM 274 and 275. It too was not part of the original Blalock Island and was instead part of the Oregon shoreline during pre-reservoir days. The island is 2.2 miles long and is approximately 1/2 mile southeast of Big Blalock Island. The U.S. Board of Geographic Names made "Long Walk Island" the official name in 1983.

"Coyote Island" was an island just south of the original Blalock Island, and was located just off the Oregon shore slightly upstream of the old Oregon town of Coyote. Coyote Island is now under the waters of Lake Umatilla.

"... Wed.y. 12th Fine weather, fresh breeze from the Westward. Embarked before sunrise and had a nice sail wind all day. Encamped in the evening a little below Big Island. A good many Indians along the river, but not many salmon. ..." [Work, July 12, 1826]

The 1858 map "Map of military reconnaissance from Fort Dalles, Oregon, via Fort Wallah-Wallah, to Fort Taylor, Washington Territory, 1858. " has the island labeled "Long Island".

In 1899 the entire island was purchased by Dr. Nelson G. Blalock, a Civil War surgeon and a pioneer railroad developer. He built a pumping plant on the southeastern shore of Blalock Island to be used for irrigation. Dr. Blalock planted extensive orchards on the island. (Downstream of the Blalock Islands is Blalock Canyon, a location which Dr. Blalock had hoped to develop into another agricultural center.)

The 1906 USGS Topo 1:125,000 "Blalock Island" has the island labeled "Blalock Island".

Today the original large "Blalock Island" is under the waters of Lake Umatilla, the reservoir behind the John Day Dam, and only small islands dotting the Columbia are left. These islands are now known as "Blalock Islands". In 1983 the U.S. Board of Geographic Names made official the names of the smaller islands - "Big Blalock Island", "Little Blalock Island", "Sand Island", and "Rock Island".

"Rock Island is on the Columbia River above John Day Dam near the Town of Irrigon (OR), and is owned and managed by the U.S. Fish and Wildlife Service as part of the Umatilla National Wildlife Refuge. Rock Island is a small, low-lying gravel island (ca. 0.5 acre) that was created by the John Day Dam impoundment and is part of the Blalock Island complex. The first documentation of Caspian terns nesting on Rock Island was in 2005, when 6 breeding pairs attempted to nest and has grown to ca. 80 breeding pairs in 2009. Caspian terns continue to attempt to nest on Rock Island, but nesting success has remained low due to a variety of factors, including mink predation, avian predation, and fluctuating water levels in the John Day Pool. About 700 pairs of ring-billed gulls also use Rock Island as a nesting site." Source:    "Bird Research Northwest" website, 2019.