Upper Missouri River Bank Erosion Montana and North Dakota 1991
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Upper MíssouriRiuer BankErosion . cLASaOU Ff. ?ECr RIY¡ I tto I rr¡outl D IIELETA. U3 ¡¡LtÍt LL rvtt ¡ltIArcx C I 1É J = c F F H KOTA f M ¡¡LL FOUTCHT tvt i ¡t tt ll¡ DAr ¡ ¡¡¡D I el gAYI stoux cllY Poltl 1 lllo DA¡ Ar{A NEB RASKA Montaraa and N orth D akota ApríL 1991 UPPER MTSSOURI RIVER BANK EROSION MONTÀNÀ ÀND NORTH DÀKOTÀ Prepared by: d'cvzr- Bruce Enge El Ìlaren, g st North Dakota State Tlater Montana Department of Natural Commission Resources and Conservation Submitted by: Fr , P.E. t tor , Superv sor llater Development Division Hydrosc iences Section North Dakota State I{ater I4ontana Department of Natural Commission Resources and Conservation Approved by: av , G , State Engineer ïva Res s Division North Dakota State Ï{ater Montana Department of NaturaL Commission Resources and Conservation TÀBLE OF COI*TENTS Page I. INTRODUCTION 1 Problem Statement. 1 Purpose and Scope. 1 Descript,ion of the Study Àrea. 2 II. HISTORICÀL 5 Before the Dams. 5 The Dams 7 Àfter the Dams B III. EXISTTNG ÀIIIIIORITIES 11 rv. JUSTIFICÀTIOIÙS 13 Upper Basin Sacrifices 13 Reservoirs 13 Bànk Erosion L4 Future Problems. L7 Delta Formation. 18 Benefits 18 Flood Control. 19 Navigation 2L Irrigation 22 Hydropower 23 Recreation 24 Dam Operations 25 Responsibility 30 Historical Sites 32 Repair of Existing Structures 33 V. DÀUAGED ÀRE,AS. 36 Existing Structures. 36 Site Selection 36 Montana. 39 North Dakota 39 Cost Estimates 40 Erosion Sites. 4L VT. PEÀSE 1 - CRITICÀI, ÀRE,A, - BÀIIK STÀBILIZÀTION PT,AI¡. 52 VII. SUIII,fÀRY. 54 -r- TÀBLB OF CONTENTS ( COIüT. ) Paqe TÀBLES TabIe 1 Land Acquired for Reservoirs 13 TabIe 2 Comparison of Post Dam Stream Bank Erosion Rates 15 TabIe 3 Dístribution of Benefits and Cost of Pick-Sloan PIan. 19 Table 4 Electric Power. 23 Table 5 Structures Needing Repair 37 Table 6 Erosion Sites, Fort Peck Dam to Lake Sakakawea. 42 TabIe 7 Erosion Sites, Garrison Dam to Lake Oahe. 45 TabIe I Sites Needing Protection fmmediately. 47 Table 9 Sites Needing Protection Soon 47 Table 10 Noncritical Sites 49 FIGIIRES Figure 1 I'lissouri River Basin. 3 Figure 2 Upper Basin 4 Figure 3 Itfissouri River Flow at IùoÌf Point, Dfontana. 27 Figrrre 4 Missouri River FIow at, Bismarck, North Dakota 27 Figrrre 5 Power Peaking Operations Fort Peck Dam. 28 Figure 6 Missouri River Discharge WoIf Point 29 Figrrre 7 Ìlissouri River Stage Wol-f Point, 29 ÀPPEIIDIXÀ-Section33 ÀPPEIüDIX B - Resolutions and Letters of Support ÀPPEIüDIX C - Photographs -t_r- I. TNIR.ODUCTIOIÜ Problen Statenrent Since the completion of the Ìfissouri River main stem reservoirs, the net ross of highty valued land.s along t,he river in the upper basin states has increased substantially. The loss of these lands has adversely impacted landowners, local and state governments, rndian Reservations, recreation, witdrife, and. the environment. The corps of Engineers, who operate the main stem dar¡s, are responsible for the bank erosion. However, the corps has refused to correct the damage being done. The congress of the united states has directed the secretarT of the Àrmy to undertake such measures, including maintenance and rehabilitation of existing structures, which the Secreta:r¡r deter:rrines are needed. to alleviate bank erosion and related problems. By this action the Congress acknowledges that the federal government, through the corps of Engineers, is responsibre for the bank erosion. Howeverr Do money has been appropriated to atlow the corps to meet their responsibility. Purpose and Scope This report' reviews the history of the development, of the Missouri River system, presents justifications for bank protection measures, and itemizes erosion sites. Àlthough this report emphasizes the probrems in Montana and North Dakota, information from Nebraska and South Dakota is included as these t\øo states are also losing land to bank erosion. -1- The organizations supporting this report, hope the informa- tion provided wilr persuade the united states congress to appropriat'e sufficient funds to alleviate the damage occurring in the upper basin states. The organizations also hope the Congress will dÍrect the coqps of Engineers to repair the damage caused by the'dams they control. Description of the Study Àrea The Dlissouri River drainage basin consists of 529rOO0 sçluare miles and includes all or parts of ten states, Figure 1. There are six main stem dams located along the thousand mile reach of the Missouri River extending from yanlrton, south Dakota to Glasgow, Molrtana. Open reaches of river exist between Fort peck and Lake sakakawea (204 miles), Garrison and take oahe (g? miles), oahe and Lake sharpe (5 mires), Fort, Randall and Lewis and Clark Lake (44 nriles), and downstrearn of Gavins .point Dam (58 miles). The area upstream of the point 58 ¡¡iles downstrean of Gavins Point is referred to as the upper basin, Figure 2. The five open reaches are the focus of this report with emphasis given to the reaches between Fort Peck and Lake Sakakawea and betrøeen Garrison and Lake Oahe. -2- __c4ll ,ro4 FIGURE I L E CEND o TI DÀKOTA ?t w0tn lN oPtMtþr coxsr ¡cItvE t¡(! t a4a u0. Rtvt LtYtE toc^L PRoItCItoI i o *att tAr(t a> tÞ Nr^ cùari¡rVt N/t N^Yrolltox AI0 'r?ly. tf^ôtLllAIt0t Pn0t ^rvc¡ æNftt alaa{ ú ,ca,¿ù¿tu 4lama rût atø tfu.aa T ¿lKO A ¡ro ¡qo l^v aa.3 I l¡) æ¿a¿. trval I tl toxca, N ¡rdx cllv IOwÀ N a EB 4r¡a*41þi T , I I crl coL , I 0llrtrcl 03t¡AÂCAttil I I a ÍAÉAl CIlY¡ I . f^E^¡ clr. CORPS OF ENGINEERS - trtlll alut irwr Llx:¡ ltorcvlfr ¡ llw r.irF¡) a - tluc ilYSi 6 XAXX:L M ISSOURI RIVER a Lltllc llvt t, cñax. 4' DIVISION - taart r ¡\al CIVIL WORKS PROJECTS AUOU!1, teôr FIGURE 2 <- STUDY AREA -.-) .0 ¡ooY f f.Pfcx ¡tv LLI ¡f or. ettroutt D 0Anttt ¡a3L f xa. t ut¡a!sx3L! 0A¡a rva ¡ tr^rcf I C I lÉ UÞ s c JO NORTH TA SOUTH KO A I J; MON TA A ITLL touicxE lvt i rllfilf oAÍ E 0^r ¡le ¡tl. D 0At t. r^¡0^L L Y^ttf a V3 I 3^Vtt ¡r0ux €¡f t oti^l^ totx f L EG ENO oA¡ V- e,o¡ton r,r¡ OT¡XA ' I - Fort p.cl O¡m lo Lrkt S¡¡.¡¡rar 2 - O¡rrlton Otm to L¡¡t O¡òt NEBRASKA rT. EISI1ORIeAIJ BÀCKGROT'ND Before the Da¡rs The Dfissouri River, before the construction of the main stem reservoirs, was a tlpical alluvial river that gradually meandered in its broad flood prain. There Ìras a barance over the years between the destruction of valrey lands by erosion of the high banks and the building of new valley lands by sediment deposited during floods. This process resulted in a continual migration of the river channel within the I'fissouri River varrey, but no Iong-te::n net loss of valley lands. The natural flows of the Missouri River varied greatly frorn \ year to year and during the year. The winter flows of the upper lfissouri River were nonrally very low since the cold temperatnres precluded rainfall and snowmelt. Groùnd water flows into the river and it,s tributaries were the only sources of flow. The cold tentperatures also caused thick ice formation on the river. Àt BÍsmarck, the ice Ìras so stable that railroad tracks \rere laid on the ice to allow trains to cross before the present bridge was constructed. Spring temperatures caused the snorr cover on the plains to melt causing a sudden surgie of high water. Normally the melt occurred in }fontana earlier than in the Dakotas. The spring runoff sometimes arrived in the Dakotas before the ice on the river had melted causing ice jams and flooding. The severity of these ice jam floods depended on the amount of water and t_he Ê amount and hardness of the ice. During these ice jam floods, Iarge amounts of sedinents were deposited, building up the valley lands. The spring runoff rùas veaa¡ sudden, the riverbed. and banks rÍere st'ill frozen so amazingly little bank erosion occurred during the spring despite the high fl_o¡¿s. After the sprÍng runoff the river returned to low flows. The snow in the mountains of Montana and wyoming usuarly began melting in late üay, reached a peak in rate June, and rÍas com- pleted in July. This caused what was known as the June rise. The river channel i,ras nonrally large enough to accommodate the June rise without flooding the normar bottom rand. The lower sandbars, especially those that had a growth of willows, slowed the silt l-aden water, causing the deposition of silt and thus the beginning of ne¡'v land foruration. Nomally, low precipitation in the upper basin during the late srunmer and fall caused the river to return to moderate and low flows that cont,inued through the winter. The bottom lands of the Ìfissouri River superbly complemented the adjacent lands. The hills adjacent to the bottom lands t¡ere ideally suited to grazing cattle and the bottom lands provided hay and idear wintering quarters for the ranchers' herds. The occasional flooding or near flooding kept the water table high enough to sub-irrigate the land and the silt deposits of the floods' high in phosphate and potash, created an ideal environ- ment for many crops including forage crops for winter feed. The -6- wooded land provided all the shelter needed to protect, cattle through the winter and they were moved to higher ground before the spring flood.