Scour-Critical Bridges in Idaho

Idaho has 205 bridges rated scour-critical by the Federal Highway Administration. These bridges have foundations that are unstable or at risk of undermining during flood events. Scour-critical doesn't mean a bridge is about to collapse — it means extra monitoring and countermeasures are in place — but these structures are priorities for repair or replacement.

How this ranking works

This state list filters to NBI scour ratings 0 through 3, then sorts by average daily traffic. It is intended to show flood-vulnerability exposure, not to label any bridge as currently unsafe.

Bridge	County	Scour Rating	Daily Traffic	Condition
S 25 E; S Hitt RD over Sand Creek	Bonneville	3 — Serious	27,500	Poor
I 84b;centennial W over Uprr;indian Cr;caldwell	Canyon	3 — Serious	26,000	Fair
US 30 Ebl Spur over Snake R;fruitland Bridge	Payette	3 — Serious	24,500	Good
Sma 9773;linder RD over Boise River;n. Channel	Ada	3 — Serious	22,000	Good
US 12 over US 12;snake River	Nez Perce	3 — Serious	21,000	Fair
US 12 over Clearwater River;bnrr	Nez Perce	3 — Serious	21,000	Fair
US 95 over Payette River	Payette	3 — Serious	19,500	Fair
US 26 Ebl & Wbl over Snake River;w.blackfoot	Bingham	3 — Serious	18,000	Fair
I 84b Sbl over Snake River;heyburn Br.	Cassia	3 — Serious	17,000	Fair
Nhs 7553;capitol over Boise River	Ada	3 — Serious	16,500	Fair
I 84b Nbl over Snake River;heyburn Br.	Cassia	3 — Serious	15,000	Fair
US 95 over Kootenai R;uprr;bnnrs Fy	Boundary	3 — Serious	13,000	Fair
I 15 Nbl over Blackfoot River	Bingham	3 — Serious	12,500	Fair
I 15 Sbl over Blackfoot River	Bingham	3 — Serious	12,500	Fair
Stp 7363;americana over Boise River	Ada	3 — Serious	12,000	Fair
SH 33 over Teton Creek	Teton	3 — Serious	11,500	Fair
US 95 over Snake River;homedale Br.	Owyhee	3 — Serious	11,000	Fair
US 20 Wbl over S.fk.teton River	Madison	3 — Serious	10,000	Fair
US 20 Ebl over S.fk.teton River	Madison	3 — Serious	10,000	Fair
I 84 Ebl over Rd;uprr;snake R;glenns F	Elmore	3 — Serious	9,750	Fair
I 84 Wbl over Rd;uprr;snake R;glenns F	Elmore	3 — Serious	9,750	Fair
I 84 Ebl over Snake River;king Hill	Elmore	3 — Serious	9,750	Fair
I 84 Wbl over Snake River;king Hill	Elmore	3 — Serious	9,750	Fair
I 90 Ebl over S.fk.coeur Dalene River	Shoshone	3 — Serious	9,500	Fair
I 90 Wbl over S.fk.coeur Dalene River	Shoshone	3 — Serious	9,500	Fair
I 15 Nbl over Portneuf River	Bannock	3 — Serious	8,000	Fair
I 15 Sbl over Portneuf River	Bannock	3 — Serious	8,000	Fair
7th AVE N. over Indian Creek	Canyon	3 — Serious	8,000	Good
SH 55 over S.fk.payette River	Boise	3 — Serious	7,300	Fair
US 93 over Salmon River;salmon Br.	Lemhi	3 — Serious	7,300	Poor
I 90 Ebl over Coeur Dalene River	Kootenai	3 — Serious	7,000	Fair
I 90 Wbl over Coeur Dalene River	Kootenai	3 — Serious	7,000	Fair
US 95 over Lapwai Creek	Nez Perce	3 — Serious	7,000	Fair
US 95 over Lapwai Creek	Nez Perce	3 — Serious	7,000	Fair
I 90 Ebl over S 5750;pine Cr;pinehurst	Shoshone	3 — Serious	7,000	Fair
I 90 Wbl over S 5750;pine Cr;pinehurst	Shoshone	3 — Serious	7,000	Fair
I 86 Ebl over Portneuf River	Power	3 — Serious	6,750	Fair
I 86 Wbl over Portneuf River	Power	3 — Serious	6,750	Fair
Sma 7643;eckert RD over Boise River(barber Br)	Ada	3 — Serious	6,700	Poor
I 90 Ebl over S.fk.coeur Dalene River	Shoshone	3 — Serious	6,250	Fair
I 90 Wbl over S.fk.coeur Dalene River	Shoshone	3 — Serious	6,250	Fair
I 84 Ebl over Raft River	Cassia	3 — Serious	5,750	Fair
I 84 Wbl over Raft River	Cassia	3 — Serious	5,750	Fair
I 90 Ebl over S.fk.coeur Dalene River	Shoshone	3 — Serious	5,750	Fair
I 90 Wbl over S.fk.coeur Dalene River	Shoshone	3 — Serious	5,750	Fair
Stc 5757;hill ST over S.fk.coeur Dalene River	Shoshone	3 — Serious	5,600	Fair
Stp 7343;fairview over Boise River	Ada	3 — Serious	5,500	Fair
Stp 7343;fairview over Boise River	Ada	3 — Serious	5,500	Fair
US 20 26;fap 21spr over Snake River;nyssa Bridge	Canyon	3 — Serious	5,300	Fair
SH 52 over Snake River;payette Br.	Payette	3 — Serious	5,100	Poor
US 30 over Portneuf River;mccammon	Bannock	3 — Serious	4,700	Fair
SH 55 over N.fk.payette River	Boise	3 — Serious	4,700	Fair
SH 46 over Snake River;ken Curtis	Twin Falls	3 — Serious	4,700	Fair
US 95 over Dry Creek	Washington	3 — Serious	4,400	Fair
SH 55 over Round Valley Creek	Valley	3 — Serious	4,100	Fair
SH 200 over Pack River	Bonner	3 — Serious	4,000	Fair
US 95 over Boise River	Canyon	3 — Serious	3,900	Fair
I 90b Loop over S.fk.coeur Dalene River	Shoshone	3 — Serious	3,200	Fair
US 95 over Rush Creek	Washington	3 — Serious	3,200	Fair
US 95 over Weiser River	Washington	3 — Serious	3,200	Fair
US 2 over Priest River	Bonner	3 — Serious	3,100	Poor
Stc6731;w 145 N over Snake River	Bonneville	3 — Serious	2,800	Fair
SH 34 over Bear River;riverdale Br	Franklin	3 — Serious	2,800	Fair
Batiste Road over Portneuf River	Power	3 — Serious	2,700	Good
Stc2715;4100 N. RD over Cedar Draw	Twin Falls	3 — Serious	2,700	Fair
US 95 over Little Salmon River	Adams	3 — Serious	2,600	Fair
US 93 over Spring Creek	Butte	3 — Serious	2,600	Good
US 95 over Little Salmon River	Idaho	3 — Serious	2,600	Fair
US 95 over Little Salmon River	Idaho	3 — Serious	2,600	Fair
US 95 over Little Salmon River	Idaho	3 — Serious	2,600	Fair
US 30 over Malad R.;n.hagerman Br.	Gooding	3 — Serious	2,100	Fair
US 20 over Chimney Cr.;sheep Cr.	Camas	3 — Serious	1,900	Fair
US 20 over W.fk.soldier Creek	Camas	3 — Serious	1,900	Fair
US 20 over Soldier Creek	Camas	3 — Serious	1,900	Fair
US 20 over Johnson Creek	Camas	3 — Serious	1,900	Fair
US 20 over Knowlton Creek	Camas	3 — Serious	1,900	Fair
SH 48 over Snake River Dry Bed	Jefferson	3 — Serious	1,900	Fair
Bunker AVE over S.fk.coeur Dalene River	Shoshone	3 — Serious	1,900	Poor
SH 3 over ST Maries River	Benewah	3 — Serious	1,700	Fair
I 15 Nbl over Camas Creek	Jefferson	3 — Serious	1,700	Fair
SH 78 over Snake R.;indian Cove Br.	Owyhee	3 — Serious	1,600	Fair
SH 167 over Snake River;grandview Br	Owyhee	3 — Serious	1,600	Fair
Stc 6774;e 2000 N over S.fk.teton River	Madison	3 — Serious	1,500	Fair
Stc2866;baseline R over Snake R.(montgomery Br)	Minidoka	3 — Serious	1,500	Poor
SH 51 over Bruneau River	Owyhee	3 — Serious	1,500	Fair
SH 75 over Big Wood River	Blaine	3 — Serious	1,400	Fair
Stc3830;idaho BLVD over Payette River;e.letha Br	Gem	3 — Serious	1,400	Fair
S5765;silvr Valley over S.fk.coeur Dalene River	Shoshone	3 — Serious	1,400	Fair
Stc 5786;colburn over Pack River	Bonner	3 — Serious	1,300	Fair
SH 36 over Bear River	Franklin	3 — Serious	1,300	Fair
Stc 1757;main ST over Portneuf River	Bannock	2 — Critical	1,200	Poor
US 30 over Thomas Fork Creek	Bear Lake	3 — Serious	1,200	Fair
SH 21 over Clear Creek;at Lowman	Boise	3 — Serious	1,200	Fair
SH 75 over Salmon River	Custer	3 — Serious	1,100	Fair
US 93 over Pahsimeroi River	Custer	3 — Serious	1,100	Fair
Stc 6774;teton HWY over S.fk.teton River	Fremont	3 — Serious	1,100	Poor
Chicago St. over Boise River	Canyon	3 — Serious	1,000	Fair
Stc 6760;w4000n over N.fk.snake R.;hibbard Br	Madison	3 — Serious	1,000	Fair
I 90ramp WB On over Pine Creek;wb On Ramp	Shoshone	3 — Serious	970	Fair
Stc5752;cda Rvr RD over Coeur Dalene River	Shoshone	3 — Serious	960	Poor
Stc5711;st Joe Rvr over ST Joe River	Shoshone	3 — Serious	930	Fair
SH 78 over Brown Creek	Owyhee	3 — Serious	880	Fair
S5786;colburn Culv over Grouse Creek	Bonner	3 — Serious	870	Poor
Colburn Culver RD over Pack River	Bonner	3 — Serious	870	Poor
2nd AVE N over Indian Creek	Canyon	3 — Serious	800	Fair
SH 75 over Salmon River	Custer	3 — Serious	800	Fair
Bailey Road over Bear River	Caribou	3 — Serious	760	Fair
SH 75 over Yankee Fk Of Salmon Rivr	Custer	3 — Serious	680	Poor
Stc 1699;canyon RD over Coeur Dalene River	Kootenai	3 — Serious	680	Poor
Stc3854;blk Brdg over Payette River	Payette	3 — Serious	650	Fair
SH 46 over Camas Creek	Camas	3 — Serious	630	Fair
SH 46 over Minear Creek	Camas	3 — Serious	630	Poor
SH 46 over Knowlton Creek	Camas	3 — Serious	630	Fair
I 90ramp EB Off over Pine Creek;eb Off Ramp	Shoshone	3 — Serious	630	Fair
SH 21 over Cape Horn Creek	Custer	3 — Serious	620	Fair
Stc 3811;pine RD over Lime Creek	Elmore	3 — Serious	620	Fair
Stc 3811;fh61 RD over S.fk.boise River	Elmore	3 — Serious	620	Fair
US 12 over Crooked Fk.clearwater R.	Idaho	3 — Serious	610	Fair
Stc5752;cda Rvr RD over Coeur Dalene River	Shoshone	3 — Serious	610	Fair
Rock Creek Road over Palouse R;se.potlatch Br	Latah	3 — Serious	580	Fair
SH 78 over Castle Creek	Owyhee	3 — Serious	580	Fair
Stc 1809;dingle RD over Bear River;n.dingle Br.	Bear Lake	3 — Serious	560	Fair
Stc 3851;hexon RD over Boise River	Canyon	3 — Serious	560	Poor
Stc 1843;e 800 N over Sand Creek	Bingham	3 — Serious	550	Fair
Stc4705;doumecq RD over Salmon R;whitebird Truss	Idaho	3 — Serious	550	Poor
Stc3906;warren Wgn over N.fk.payette River	Valley	3 — Serious	550	Fair
Stc 6749;2500n over Big Lost River	Butte	3 — Serious	500	Fair
Stc 3830;freemont over Payette River	Payette	3 — Serious	480	Fair
SH 3 over ST Maries River	Shoshone	3 — Serious	460	Poor
Stc 3810; Frontage over Snake R.;glenns Ferry Br	Elmore	3 — Serious	430	Fair
SH 21 over S.fk.payette R;lowman Br	Boise	3 — Serious	410	Fair
Stc2781;1300 S. RD over Thorn Creek	Gooding	2 — Critical	360	Poor
Banks Grade over N. Fk. Payette River	Boise	3 — Serious	350	Good
Stc 1775;turner RD over Bear R.;grace-turner Br.	Caribou	3 — Serious	350	Fair
Stc 3800;carbarton over N.fk.payette River	Valley	3 — Serious	330	Good
Stc8215;weiser Rvr over Manns Creek	Washington	3 — Serious	330	Fair
Stc 4805;cedar Rdg over Potlatch River	Latah	3 — Serious	320	Fair
Montour Road over Payette Rvr(montour Br)	Gem	3 — Serious	310	Fair
Bern Road over Bear River;bern Bridge	Bear Lake	3 — Serious	300	Fair
Stc 5804;westside over Trout Creek;n.branch	Boundary	3 — Serious	300	Fair
N 2750 E over Teton River	Fremont	3 — Serious	300	Good
Ohio Avenue over Pine Creek	Shoshone	3 — Serious	300	Fair
Stc 6749; 2900n over Big Lost River	Butte	3 — Serious	260	Fair
S3802;slick Ranch over Snake Rvr(slick Bridge)	Elmore	3 — Serious	260	Fair
S6810;packsaddle R over Teton River(cache Br)	Teton	3 — Serious	250	Fair
Cooper Pass Road over Canyon Creek	Shoshone	2 — Critical	220	Poor
SH 11 over Canal Creek;pierce Br.	Clearwater	3 — Serious	210	Good
SH 11 over Quartz Creek;three Mile	Clearwater	3 — Serious	210	Fair
S 2000 E over Darby Creek	Teton	3 — Serious	200	Good
5750 South over Teton River(white Br)	Teton	3 — Serious	190	Fair
Shoestring Road over Snake River;sw Bliss Br	Twin Falls	2 — Critical	190	Poor
4525 E over Fall River	Fremont	3 — Serious	180	Fair
Mission Creek Road over Mission Creek	Nez Perce	3 — Serious	180	Fair
Mcintyre Street over Lapwai Creek	Nez Perce	2 — Critical	180	Poor
Firth Wapello Road over Sand Creek	Bingham	3 — Serious	160	Good
Elk Prairie Road over ST Joe River;calder Br.	Shoshone	3 — Serious	160	Fair
100 North Road over A Canal	Minidoka	3 — Serious	150	Good
Hunter Hill Road over Bear River;e.dingle Br	Bear Lake	3 — Serious	140	Fair
Stc 1769;river RD over Bear R;cheesecake Fac Br	Caribou	3 — Serious	140	Fair
Stc 5803;moyie Rvr over Moyie River;meadow Creek	Boundary	3 — Serious	120	Fair
Stc5758;beaver Crk over Beaver Creek	Shoshone	3 — Serious	110	Fair
Old Hornet Road over Hornet Creek	Adams	2 — Critical	100	Poor
N Kraft Road over Portneuf River	Bannock	3 — Serious	100	Fair
E 1000 N over Conant Creek	Fremont	3 — Serious	100	Fair
Potlatch Road over Big Creek Trestle	Shoshone	2 — Critical	100	Poor
East Fork RD over Road Creek	Custer	2 — Critical	90	Poor
Neal Road over S.fk.boise River	Elmore	3 — Serious	90	Fair
Stc 5725;latour CR over Latour Creek;sw.cataldo	Kootenai	3 — Serious	90	Fair
Smith Ferry Drive over N.fk.payette River	Valley	3 — Serious	90	Poor
Main Street South over Jim Ford Creek	Clearwater	2 — Critical	80	Poor
S Roecks Road over Rose Creek	Kootenai	3 — Serious	80	Fair
Tom Beall Road over Lapwai Creek	Nez Perce	3 — Serious	80	Good
County Road over Bear River	Bear Lake	3 — Serious	70	Fair
N 1600 E over ST Anthony Canal	Fremont	2 — Critical	70	Poor
Kilpatrick Br. Rd. over Silver Creek	Blaine	2 — Critical	60	Poor
Hot Springs Road over Bruneau River	Owyhee	3 — Serious	60	Fair
Summit Flat Road over Clear Creek	Boise	3 — Serious	50	Fair
Fs Route No. 2450 over Blue Joe Creek	Boundary	2 — Critical	50	Poor
Fall Ck.-rocky Bar over East Fork Fall Creek	Elmore	2 — Critical	50	Poor
1200 South Road over Clover Creek	Gooding	3 — Serious	50	Fair
Forest Road 1614 over French Creek	Idaho	2 — Critical	50	Poor
Forest Road 651 over Selway River-ohara	Idaho	2 — Critical	50	Poor
N Crane Road over Crane Creek	Washington	3 — Serious	50	Fair
S Anderson Lake RD over Cda River;springston Br	Kootenai	3 — Serious	40	Poor
S Bates RD over Teton Rvr (nickerson Br)	Teton	3 — Serious	40	Good
East Fork Road over E.fk. Of S.fk.salmon Rvr	Valley	3 — Serious	40	Fair
Wildhorse Road over Wildhorse River	Adams	3 — Serious	30	Poor
Blackfoot Road over Blackfoot R. & Trail Cr.	Bingham	3 — Serious	30	Fair
White Mtn Road over Dodge Creek	Boundary	3 — Serious	30	Fair
Fall Creek RD over Fall Creek	Elmore	2 — Critical	30	Poor
Stc 3809;middle Fk over Black Warrior Creek	Elmore	2 — Critical	30	Poor
Idfg Access Road over Salmon River	Lemhi	3 — Serious	30	Fair
River Road over Salmon Falls Creek	Twin Falls	3 — Serious	30	Fair
Deadwood Road over Deadwood River	Valley	3 — Serious	30	Fair
Stibnite Road over Tamarack Creek	Valley	3 — Serious	30	Fair
E Fork Road over Wildhorse Creek	Custer	3 — Serious	25	Fair
2416: Teakettle Ro over Y-1 Canal	Gooding	3 — Serious	25	Good
4248: Shoshone Cre over Shoshone Creek	Twin Falls	3 — Serious	25	Good
Roaring River Road over Middle Fork Boise River	Elmore	2 — Critical	20	Poor
Rammage Meadows RD over Third Fk.chief Eagle Eye	Gem	1 — Imminent failure	20	Poor