In 1806 and 1806 Lewis and Clark noted the two mouths with an "island" inbetween.

"... a verry Considerable Stream Dischargeing its waters through 2 Chanels which forms an Island of about 3 miles in length on the river and 1 1/2 miles wide, composed of Corse Sand which is thrown out of this quick Sand river ..." [Clark, November 3, 1805]

"... This morning early we dispatched Sergt. Pryar with two men in a small canoe up quicksand river with orders to proceed as far as he could and return this evening. ... Sergt. Pryar returned in the evening and reported that he had ascended the river six miles; that above the point at which it divides itself into two channels it is about 300 yds wide tho' the channel is not more than 50 yds and only 6 ft deep. ..." [Lewis, April 1, 1806]

In 1841 Charles Wilkes of the U.S. Exploring Expedition named this island "Bachelet I.", with the upper mouth being named "Quichel's R." and the lower mouth becoming "Palle Creek". These names did not stick. The upper mouth of the Sandy became the "Sandy River" and the lower mouth became the "Little Sandy River", and the "island" between them became the northern part of the "Sandy River Delta" - today the 600-acre "Sundial Island". In the 1930s, the Oregon Department of Fish diked/damed the upper mouth of the Sandy to improve the smelt run, with the waters of the upper Sandy being diverted into the lower mouth. The upper mouth became a slough as it filled in with silt. The "island" became pastureland. The area today is known as the Sandy River Delta and includes hiking trails, birding environments, and an off-leash dog park.

"... at 3 miles I arrived at the enterance of a river which appeared to Scatter over a Sand bar, the bottom of which I could See quite across and did not appear to be 4 Inches deep in any part; I attempted to wade this Stream and to my astonishment found the bottom a quick Sand, and impassible -- I called to the Canoes to put to Short. I got into the Canoe and landed below the mouth. & Capt Lewis and my Self walked up this river about 1 1/2 miles to examine this river which we found to be a verry Considerable Stream Dischargeing its waters through 2 Chanels which forms an Island of about 3 miles in length on the river and 1 1/2 miles wide, composed of Corse Sand which is thrown out of this quick Sand river Compressing the waters of the Columbia and throwing the whole Current of its waters against its Northern banks, within a Chanel of 1/2 a mile wide, Several Small Islands 1 mile up this river, This Stream has much the appearance of the River Platt: roleing its quick Sands into the bottoms with great velocity after which it is divided into 2 Chanels by a large Sand bar before mentioned, the narrowest part of this River is 120 yards ..." [Clark, November 3, 1805]

What caused this sand bar ??? ... According to Cynthia Gardner of the U.S. Geological Survey [Gardner, et.al., 2000] an eruption of Mount Hood occurred a few years before the passage of Lewis and Clark.

"In 1805, Meriwether Lewis and William Clark named a river on the south side of the Columbia River gorge the "Quicksand River." Their description of a wide, shallow river with a bed "formed entirely of quicksand," bears little resemblance to the narrow, moderately deep river we call today the Sandy River. What happened? The answer lay 50 miles away at Mount Hood. An eruption in the 1790's caused a tremendous amount of volcanic rock and sand to enter the Sandy River drainage. That sediment was still being flushed downstream when Lewis and Clark saw and named the river. Since 1806, the river has removed the excess sediment from its channel. The Toutle River in southwest Washington was similarly affected by the 1980 eruptions of Mount St. Helens."

While Lewis and Clark generally called the river "Quicksand" River, the phrase "Sandy River" did appear.

"... passed the Lower mouth of Sandy river at 3 miles ...     river wide The Countrey below quick Sand river on the Lard Side is low Piney Countrey. ..." [Clark, November 3, 1805, first draft]

"... This morning our Officers sent Serjeant Pryor & 2 of our party in a Canoe in order to go 5 or Six Miles up <Quick Sand or> Quicksand or Sandy River ... " [Whitehouse, April 1, 1806]

"... Myself and 4 men went below the mouth of Sandy river, and killed an elk, some deer and a black bear. ..." [Gass, April 2, 1806]

"... The natives that were still with us, informed our Officers, that there was a large River, which emptied itself into the Columbia River, on the South side, below Sandy River ..." [Whitehouse, April 2, 1806]

"... This morning early we dispatched Sergt. Pryar with two men in a small canoe up quicksand river with orders to proceed as far as he could and return this evening. ...     Sergt. Pryar returned in the evening and reported that he had ascended the river six miles; that above the point at which it divides itself into two channels it is about 300 yds wide tho' the channel is not more than 50 yds and only 6 ft deep.     this is a large vollume of water to collect in so short a distance; I therefore think it probable that there are some large creeks falling into it from the S.W.     the bed of this stream is formed entirely of quicksand; it's banks are low and at preasent overflows.     the water is turbid and current rapid. -- the following are the courses taken by Sergt. Pryor. S.10^ow. 1 M. to a point on the Lard. side passing a large Island on Stard. S.24^oE. 2 m. to the head of an Island near the Lard. shore. S 33^oE. 4 m. to a stard. point passing several islands on the Lard. side and a creek 50 yds. wide on Stard at 1 1/2 miles.     the river from hence appeared to bend to the East.     he heard falls of water.     several different tribes informed us that it heads at Mount Hood. ..." [Lewis, April 1, 1806]

Sergeant Pryor reached as far as today's Dabney State Recreation Area, located at Sandy River Mile (RM) 6 (see more below).

"... From hence a large river bore S.5 E., which was afterwards seen to take a southwestwardly direction, and was named Baring River ..." [Broughton, October 30, 1792]

Lewis and Clark passed the Sandy River on November 3, 1805, and generally called the river "Quicksand River", altho the phrase "Sandy River" did appear in the journals (see above). Lewis and Clark also noted the fact that there were two mouths to the Sandy River, which they called the "upper mouth" and the "lower mouth", with an "island" inbetween.

"... a verry Considerable Stream Dischargeing its waters through 2 Chanels which forms an Island of about 3 miles in length on the river and 1 1/2 miles wide, composed of Corse Sand which is thrown out of this quick Sand river ..." [Clark, November 3, 1805]

In 1838 the "Map of the United States Territory of Oregon West of the Rocky Mountains, Exhibiting the various Trading Depots or Forst occupied by the British Hudson Bay Company, connected with the Western and northwestern Fur Trade. Compiled in the Bureau of Topographical Engineers, from the latest authorities, under the direction of Col. J.J. Abert, by Wash: Hood." had the river labeled "Quicksand R.".

In 1841 Charles Wilkes and the U.S. Exploring Expedition mapped this area and gave the two mouths of the Sandy separate names. The lower mouth became "Palle Creek" and the upper mouth became "Quichel's R.", with the "island" inbetween the mouths being called "Bachelet I.". Directly across from these two rivers and Bachelet Island, was "Frost I.", today known as Lady Island and "Evarts Bay", today the mouth of the Washougal River. On the Columbia River inset on Wilke's "Map of the Oregon Territory" the Washougal River is labeled "Evets R.".

The 1902 U.S. Coast and Geodetic Survey map calls the lower mouth "Little Sandy River" and the upper mouth the "Sandy River", with numerous unnamed islands shown between the two mouths.

The 1948 U.S. Coast and Geodetic Survey map also has the "Little Sandy River" downstream, and the "Sandy River" upstream, with the "Sandy River" showing a dike and siltation in its channel. Unnamed islands and sloughs are between the two mouths.

"... Sam Barlow, in the summer of 1845 arrived in The Dalles, Oregon from Missouri. He discovered another hazardous portion of the Oregon Trail. The Columbia River! This river must either be crossed twice or rafted down at exorbitant prices. He learned that he could follow an old Indian Trail around the south side of Mount Hood, a route that had not been used by fellow immigrants. The initial Barlow Road was used early in 1846, and was 80 to 90 miles in length. During the first year 145 wagons arrived by this new route, bringing to Oregon, and Sandy, nearly a thousand settlers with their droves of horses and cattle. About the best that could be said for improvements to it were the Laurel Hill section, with its 60% drop, was eliminated with switchbacks, and Mr. Revenue put a bridge over the Sandy River, and fording areas were improved. Railroads to California in the 1870's and then to Oregon in the 1880's eliminated most of the travel over the Barlow Road. ..." [Oregon Historical Society Website, 2009]

There have been two Post Office's called Sandy. Between 1854 and 1868 a Post Office named Sandy was located near the present site of Troutdale. In 1873 the Sandy Post Office of today was established.