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Yellowstone River

 About the Yellowstone River

Yellowston River Location Map

At the confluence of the Missouri and Yellowstone Rivers, the Yellowstone River is actually the larger river.  Both rivers historically flood during the spring, and ice jams have caused dramatic flood events.  The Missouri River’s flow and water quality have been altered greatly by Fort Peck Dam.  However, "the Yellowstone River, the longest undammed river in the contiguous United States, retains most of its natural habitat characteristics and flows" (Ryckman, 2000).

 Captain Lewis

Thursday, April 25, 1805, on the Missouri River, near the entrance of the Yellowstone River

Grazing Bison in Theodore Roosevelt National Park Courtesy National Park ServiceThe wind was more moderate this morning, tho’ still hard; we set out at an early hour.  the water friezed on the oars this morning as the men rowed.  about 10 oclock A.M. the wind began to blow so violently that we were obliged to lye too. . . . The wind had been so unfavorable to our progress for several days past, and seeing but little prospect of a favourable chang; knowing that the river was crooked, from the report of the hunters who were out yesterday, and believing that we were at no great distance from the Yellow stone River; I determined, in order as mush as possible to avoid detention, to proceed by land with a few men to the entrance of that river and make the necessary observations to determine its position, which I hoped to effect by the time that Capt. Clark could arrive with the party; accordingly I set out at 11OCk on the Lard. side, accompanyed by four men. . . . I ascended the hills from whence I had a most pleasing view of the country, particularly of the wide and fertile vallies formed by the missouri and the yellowstone rivers, which occasionally unmasked by the wood on their borders disclose their meanderings for many miles in their passage through these delightfull tracts of country.  I could not discover the junction of the rivers immediately, they being concealed by the wood; however, sensible that it could not be distant I determined to encamp on the bank of the Yellow stone river which made it’s appearance about 2 miles South of me.  the whol face of the country was covered with herds of Buffaloe, Elk & Antelopes; deer are also abundant but keep themelves more concealed in the woodland.  the buffaloe Elk and Antelope are so gentle that we pass near them while feeding, without appearing to excite any alarm among them. . . .
Compare the weather conditions Lewis and Clark observed to the current weather conditions.

    The courses and distances of this day (25th) being as follow.              Miles
    N. 68° W. to a point of woodland on Lard. side                              2.½
    West      to a tree in a low plain in a bend on Std.                        1.¼
    South.    to the upper part of a low bluff in a ben on Stard. side          1.½
    East.     to a point of timbered land on Stard. side.                       2.½
    S. 28° E. along the Stard. point, opposite a bluff                           .¾
    S. 20° W. along the Stard. point opposite a bluff                           1.
    N. 65° W. to the upper part of a timbered bottom in a bend on Stard. side   3.
    S. 72° W. to the lower point of some timber in a bend on Stard. side        1.¾

Friday, April 26, 1805, on the Missouri River, near the entrance of the Yellowstone River

Elk Herd in Theodore Roosevelt National Park Courtesy National Park ServiceThis morning I dispatched Joseph Fields up the yellowstone river with order to examine it as far as he could conveniently and return the same evening; . . . while I proceeded down the river with one man in order to take a view of the confluence of this great river with the Missouri, which we found to be two miles distant on a direct line N. W. from our encampment.  the bottom land on the lower side of the yellowstone river near it’s mouth, for about one mile in width appears to be subject to inundation; while that on the opposite side of the Missouri and the point formed by the junction of these rivers is of the common elivation, say from twelve to 18 feet above the level of the water, and of course not liable to be overflown except in extreem high water, which dose not appear to be  very frequent.  there is more timber in the neighbourhood of the junction of these rivers, and on the Missouri as far below as the White-earth river, than there is on any part of the Missouri above the entrance of the Chyenne river to this place.  the timber consists principally of Cottonwood, with some small elm, ash and boxalder.  the under growth on the sandbars and verge of the river is the small leafed willow; the low bottoms, rose bushes which rise to three or four fet high, the redburry, servicebury, and the redwood; the high bottoms are of two discriptions, either timbered or open; the first lies next to the river and it’s under brush is the same with that of the low timbered bottoms with the addition of the broad leafed willow, Goosbury, choke cherry, purple currant, and honeysuckle bushis; the open bottoms border on the hills, and are covered in many parts by the wild hyssop which rises to the hight of two feet.  I observe that the Antelope, Buffaloe Elk and deer feed on this herb; the willow of the sandbars also furnish a favorite winter food to these anamals as well as the growse, the porcupine, hare, and rabbit. . . . in the evening, the man I had sent up the river this morning returned, and reported that he had ascended it about eight miles on a streight line; that he found it crooked, meandering from side to side of the valley formed by it; which is from four to five miles wide.  the corrent of the river gentle, and it’s bed much interrupted and broken by sandbars; at the distance of five miles he passed a large Island well covered with timber, and three miles higher a large creek falls in on the S. E, side above a high bluff in which there are several stratas of coal.  the country bordering on this river as far as he could percieve, like that of the Missouri, consisted of open plains.  he saw several of the bighorned anamals in the couse of his walk; but they were so shy that he could not get a shoot at them; he found a large horn of one of these anamals which he brought with him.  the bed of the yellowstone river is entirely composed of sand and mud, not a stone of any kind to be seen in it near it’s entrance.  Capt Clark measured these rivers just above their confluence; found the bed of the Missouri 520 yards wide, the water occupying 330.  it#&8217;s channel deep.  the yellowstone river including it’s sandbar, 858 yds. of which, the water occupyed 297 yards; the depest part 12 feet; it was falling at this time & appeard to be nearly at it’s summer tide.  the Indians inform that the yellowstone river is navigable for perogues and canoes nearly to it’s source in the Rocky Mountains, and that in it’s course near these mountains it passes within less than half a day’s march of a navigable part of the Missouri.  it’s extreem sources are adjacent to those of the Missouri, river platte, and I think probably with some of the South branch of the Columbia river.1 . . .  the water of this river is turbid tho’ dose not possess as much sediment as that of the Missouri. . . . a sufficient quantity of limestone may be readily procured for building near the junction of the Missouri and yellowstone rivers.  I could observe no regular stratas of it, tho’ it lies on the sides of the river hills in large irregular masses, in considerable quantities; it is of a light colour, and appears to be of an excellent quality.

    The courses and distances of the 26th as the party ascended the Missouri, are as follow      Miles
    S. 45. E. to a point of woodland on the Stard. side                                            2½
    S. 40. W. along the Stad. point, opposite a bluff                                              1½
    N. 75. W. to the commencement of the wood in a bend on Stard. side                             3.
    South.    to the point of land formed by the junction of the Missouri and yellow stone rivers  1.
                                                                                             Miles 8.-
    Point of Observation No. 7. April 26th 1805.
    On the lard bank of the yellowstone river 2 miles S.E. of it’s junction with the Missouri observed 
      Equal altitudes of the sun with Sextant and artificial horizon.
               h     m     s
               9.   41.   13.   __             6.   49.    3.      Atd. given by Sextant at the time of
      A. M.    ".   42.   52.   __     P.M.    ".   50.   41.      observation
               ".   44.   31.   __             ".   52.   17.      48° 57′. 45"
                                                                   h.   m.   s.
    Chronometer too fast mean time.  he clouds this morning prevented my observing the moon with a.
    Aquilae; and as the moon was not again observeable untill the 1st of May, I determined not to wait,
    but reather to relinquish for the present the obtaining the necessary data to fix the longitude of 
    this place.
    Observed Meridian altitude of sun’s L.L. with Octant by the back observation 73°47′ Latitude deduced 
    from this observation.

 Captain Clark

Friday, April 26, 1805, on the Missouri River, near the entrance of the Yellowstone River

. . . on the forks about 1 mile from the point at which place the 2 rivers are near each other a butifull low leavel plain commences, and extends up the Missouri & back, this plain is narrow at its commencement and widens as the Missouri bends north, and is bordered by an extencive wood land for many miles up the Yellow Stone river, this low plain is not Subject to over flow, appear to be a fiew inches above high water mark and affords a butifull commanding situation for a fort2 near the commencement of the Prarie, about [blank space in MS.] miles from the Point & [blank space in manuscript.] yards from the Missouri a small lake is Situated, from this lake the plain rises gradually to a high butifull countrey, the low Plain continues for some distance up both rivers on the Yellow Stone it is wide & butifull opsd.  the point on the S. Side is some high timbered land, about 1 1/2 miles below on the same side a little distance from the water is an elivated plain. . . . I Saw maney buffalow dead on the banks of the river in different places some of them eaten by the white bears & wolves all except the skin & bones, others entire, those animals either drounded in attempting to cross on the ice dureing the winter or swiming across to bluff banks where they could not get out & too weak to return  we saw several in this Situation.  emence numbers of antelopes in the forks of the river, Buffalow & Elk & Deer is also plenty.  beaver is in every bend.  I observe that the Magpie  Goose duck & Eagle all have their nests in the Same neighbourhood, and it is not uncommon for the Magpie to build in a few rods of the eagle, the nests of this bird is built verry strong with sticks covered verry thickly with one or more places through which they enter or escape, the Goose I make no doubt falls a pray to those vicious eagles

 Confluence of the Missouri and Yellowstone Rivers

Confluence of the Missouri and Yellowstone Rivers

The Missouri River is the river flowing from west to east in the above July 28, 1995, photograph.
The Yellowstone River flows from the south into the Missouri River.

 Current Streamflow Data

To view current water-level and streamflow data for the USGS gaging station on the Yellowstone River near Cartwright, North Dakota, click on the link below.

Data for other  gaging stations on the Yellowstone River are available at NWISWeb.

 Water-Discharge and Gage-Height Records

The USGS maintains water-discharge and gage-height records for the Yellowstone River. Click on the links below to view the data.

It is necessary to have Adobe® Acrobat® or Adobe® Acrobat® Reader® installed on your computer in order to view some U.S. Geological Survey reports.  Acrobat Reader, is a free download it from Adobe Systems, Inc.


1This information about the headwaters is erroneous (DeVoto, 1953).

2Fort Union Trading Post was established near the confluence in 1829.   According to the North Dakota Tourism Department, "This was the largest and most imposing trading post on the Missouri River during the fur trading era.  Built near the confluence of the Yellowstone and Missouri Rivers by John Jacob Astor’s powerful American Fur Company, Fort Union controlled the trading economy of the Northern Plains between 1828 and 1867."  Later, the United States government built Fort Buford near the confluence.  According to the Fort Buford 6th Infantry Regimental Association, "In August of 1864 Sully’s command arrived at Fort Union, which was by then a rundown facility. General Sully scouted out the area and chose a site three miles to the east of Fort Union, overlooking the confluence directly, for the construction of a new post for the military."


DeVoto, Bernard, ed., 1953, The Journals of Lewis and Clark: New York, Mariner Books Houghton Mifflin Company, 504 p.

Fort Buford 6th Infantry Regimental Association, n.d., Confluence History: accessed June 28, 2001, at URL

North Dakota Tourism Department, n.d., Fort Union Trading Post National Historic Site: accessed June 28, 2001, at URL

Power, Greg, Fred Ryckman, Jeff Hendrickson, Jason Lee, Chris Grondahl, and Darren Bruning. 2000. ‘Cross the wide Missouri: Significant Missouri River system biological sites. North Dakota Outdoors 63(8):6-20. Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. (Version 18SEP2000). accessed June 28, 2001

Reid, Russell, ed., 1947-48, Lewis and Clark in North Dakota: Reprinted from North Dakota History, published by the State Historical Society of North Dakota, vol. 14-15, 359 p.

Theodore Roosevelt National Park, n.d., Grazing Bison: accessed July 2, 2001, at URL

Theodore Roosevelt National Park, n.d., Elk Herd: accessed July 2, 2001, at URL

U.S. Geological Survey, 1995, The Yellowstone River Entering the Missouri River: accessed June 28, 2001, at URL

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