This section is reproduced from Appendix A of TR-55, Second Ed., June 1986. It is included as a reference of soils groups throughout the United States. Soils are classified into hydrologic soil groups (HSG’s) to indicate the minimum rate of infiltration obtained for bare soil after prolonged wetting. The HSG’s, which are A, B, C, and D are one element used in determining runoff curve numbers. For the convenience of exhibit A-1 lists the HSG classification of United States soils. The infiltration rate is the rate at which water enters the soil at the soil surface. It is controlled by surface conditions. HSG also indicates the transmission rate- the rate at which the water moves within the soil. This rate is controlled by the soil profile. Approximate numerical ranges for transmission rates shown in the HSG definitions were first published by Musgrave1 (USDA 1955). The four groups are defined by SCS soils scientist as follows: Group A soils have low runoff potential and high infiltration rates even when thoroughly wetted. They consist chiefly of deep, well to excessively drained sands or gravels and have a high rate of water transmission (greater than 0.30 in/hr). Group B soils have moderate infiltration rates when thoroughly wetted and consist chiefly of moderately deep to deep, moderately well to well-drained soil with moderately fine to moderately coarse textures. These soils have a moderate rate of water transmission (0.15-0.30 in/hr). Group C soils have low infiltration rates when thoroughly wetted and consist chiefly of soils with a layer that impedes downward movement of water and soils with moderately fine to fine texture. These soils have a low rate of water transmission (0.05-0.15 in/hr). Group D soils have high runoff potential. They have very low infiltration rates when thoroughly wetted and consist chiefly of clay soils with a high swelling potential, soils with a permanent high water table potential, soils with a claypan or clay layer at or near the surface, and shallow soils over nearly impervious material. These soils have a very low rate of water transmission (0-0.05 in/hr). In exhibit A-1 (of TR-55 manual), some of the listed soils have an added modifier; for example, “Abrazo,gravelly.” This refers to a gravelly phase of the Abrazo series that is found in SCS soil map legends. Also, two soils groups such as B/C indicates the drained/undrained situation. AABAB D ACKMORE,POORLY EXTREMELY STONY C AJAX D ALDRICH C AABERG D DRAINED B AFTAD B AJO C ALECANYON A AARON C ACKNA C AFTADEN D AJOLITO D ALEDO C AARUP D ACKWATER D AFTON,DRAINED C/D AKAD C ALEGROS C AASTAD,MOIST B ACME C AGA B AKAKA A ALEKNAGIK C AAZDAHL B ACO B AGA D AKAN B/D ALEMEDA C ABAC D ACOMA C COOL C AKASKA B ALEX B ABAJO C ACORD C AGAN D AKELA D WET SUBSTRATUM C ABALAN D ACOVE C AGAR B AKERCAN B ALEXANDER C ABALOBADIAH B ACQUANGO A AGASSIZ D AKERITE B ALEXANDRIA C ABARCA B ACREDALE D AGATE D AKERS B ALFIC ABBAYE B ACREE C AGATHA B AKERUE D FRAGIORTHODS,COAR ABBEY B ACRELANE C AGAWAM B AKHONI D SE-LOAMY C ABBIE B ACRELANE B AGEE D AKINA B ALFIC HAPLAQUODS A ABBOTT D ACTI D AGENCY B AKINVILLE B ALFIC ABBOTTSPRING B ACTON B STONY C AKLER D HAPLORTHODS,SANDYA ABBOTTSTOWN C ACUFF B AGER D AKSARBEN B ALFIC UDIPSAMMENTS A ABCAL D ACUNA C AGERDELLY D ALABASTER D ALFIR B ABEGG B ACY C AGFAYAN D ALADDIN B ALFLACK A ABELA B ADA C AGNAL,ALKALI D ALADSHI B ALFLACK C ABELL B ADAIR C AGNESS B ALAE A ALFORD B ABENAKI B ADAMANT B AGNESTON B ALAELOA B ALGANSEE B ABERDEEN C ADAMS A COBBLY C ALAGA A ALGARROBO A ABERONE B ADAMSON B COBBLY SUBSTRATUMC ALAKAI D ALGERITA B ABERSITO C ADAMSVILLE C DRY C ALAMA B ALGIERS C/D ABERT B ADAMSVILLE D NONGRAVELLY C ALAMADITAS C ALGOA C ABES D DARK SURFACE B/D AGNEW C ALAMANCE B ALGOMA D ABGESE B ADATON D AGNOS D ALAMBIQUE B ALGONQUIN D ABILENE C ADAVEN C AGON C ALAMEDAWELL B ALHAMBRA B ABIN B ADCO D AGON B ALAMO D ALHARK B ABIQUA B ADDER A/D AGORT C ALAMOGORDO B ALIBI C FLOODED C ADDERTON B AGORT A ALAMOSA D ALICE B ABIQUIU C ADDICKS D AGRA D DRAINED B ALICEL B ABITA C ADDIELOU B AGUA B ALAMUCHEE B ALIBOSS STORMRAT B ABO C ADE A AGUA D ALANOS B ALIDA B ALKALI D ADEK B ALKALI C COOL D ALIKCHI B ABOR D ADEL B FLOODED D ALAPAHA D ALINE A ABORIGINE D WET D AGUA DULCE B MODERATELY WET B/D ALIVAR B ABOTEN D ADELAIDE D AGUA DULCE C ALAPAI A ALKABO C ABRA B ADELANTO B AGUA FRIA C ALAZAN C ALKIRIDGE C ABRAHAM,DRAINED B ADELINO B BEDROCK ALBAN B ALKO D ABRAM D SALINE-ALKALI C SUBSTRATUM B ALBANO D ALKO C ABRAZO D ADELPHIA B/C CLAYEY B ALBANY C ALLAGASH B GRAVELLY C ADEN C HIGH RAINFALL B ALBATON D ALLAMAKEE B ABREU B ADENA C STONY B ALBEE C ALLAMORE D ABRIGO B ADGER D AGUADILLA A ALBEMARLE B ALLANTON B/D ABSAQUIL B ADIEUX B AGUALT B ALBERS D DEPRESSIONAL D ABSAROKEE C ADILIS B AGUEDA B ALBERTON B FLOODED D ABSAROOK C ADINOT D AGUILARES B ALBERTVILLE C ALLARD B ABSCO A ADIOS D AGUILITA B ALBICALIS D ALLDOWN B ABSCOTA A ADIRONDACK,BOULDERY D AGUIRRE D ALBINAS B DRY C ABSHER D ADJIDAUMO D AGUSTIN B ALBION B ALLEGHENY B ABSTED C ADJUNTAS C AHART B ALBRIGHTS C ALLEGHENY A FLOODED D ADKINS B AHCHEW D ALBURZ C ALLEMANDS D FLOODED D ALKALI C AHL C ALBURZ D ALLEN B LOAMY SURFACE D WET C AHLSTROM D DRAINED B ALLENDALE C LOW PPT D ADLER C AHMEEK C DRAINED B ALLENDORF B ABSTON C ADMAN D AHOLT D ALBUS B ALLENS PARK B ACACIO B ADOBE D AHPAH B ALCALDE D ALLENS PARK C ACADEMY C ADOLPH B/D AHREN B ALCAN D STONY C ACADIA D ADOS C AHRNKLIN C ALCESTER,FLOODED B ALLENTINE D ACAMPO C ADRIAN A/D AHRS B ALCOA B ALLENWOOD B ACANA D ADVOKAY D AHSAHKA C ALCONA B ALLEY B ACANOD C AECET C AHTANUM D ALCOT A ALLHANDS D ACASCO D AENEAS B DRAINED C ALCOVA B ALLIANCE B ACCELERATOR B AERIC CALBOSS AHWAHNEE B ALCOVY C ALLIGATOR D ACCOLA B STORMRATQUOLLS C AIBONITO D ALDA C ALLINGHAM B ACEITUNAS B AERIC CRYAQUEPTS D AIDO D SALINE B/D ALLIS D ACEL C AERIC CRYAQUEPTS B AIKEN B ALDAX D ALLISON B ACHELAKE B AERIC FLUVAQUENTS C AIKMAN D ALDEN D ALLKER B ACHIMIN C AERIC FLUVAQUENTS B STONY C ALDER C ALLOR B ACKELTON,HARDPAN MESIC D AILEY B ALDERDALE C ALLOUEZ B SUBSTRATUM B SALINE D AIMELIIK B ALDERFLATS D ALLUVIAL LAND A ACKER B AERIC HALAQUEPTS D AINAKEA B ALDERMAND B LOAMY C ACKERMAN A/D AERIC HAPLAQUEPTS C AINSLEY B ALDERON B SANDY D ACKETT D AERIC HAPLAQUEPTS D AINSLEY C ALDERWOOD C ALLWIT D ACKLEY B AERIC HAPLAQUEPTS D AINSWORTH B ALDI D ALMAC B ACKMEN D AERIC HAPLAQUODS C AIRMONT C ALDINE D ALMANOR B ACKMEN B AFFEY C AIRPORT D ALDING D ALMAVILLE D COOL B AFLEY B AITS B ALDINO C ALMENA C Appendix - SCS Soils Groups ALMERIA D AMANDA C HARD SUBSTRATUM C ANNUM B AQUALFS ALMIRANTE B AMANDA B ANDIC ANOCON C AQUALFS D ALMO D AMARGOSA D CRVUMBREPTS,MOISTB ANOKA B AQUANDIC ALMOND C AMARILLO B ANDIC CRYAQUEPTS D ANONES C HAPLOCRYODS D ALMONT D AMAROSE B ANDIC CRYOCHREPTS B ANOWELL D AQUANDIC HUMAQUEPTSC ALMORA B AMASA B ANDIC CRYOCHREPTS C ANSARI D AQUANDS D ALMOTA C MODERATELY WET; ANDIC CRYOCHREPTS C ANSEL B AQUARIUS C ALMY B SANDY SUBSTRATU C BEDROCK ANSEL C AQUENTS D ALMY C AMBER B SUBSTRATUM C ANSELMO C AQUENTS ALNITE D AMBIA D ANDIC ANSELMO B AQUENTS ALNULT B AMBOAT D CRYUMBREPT,OVERBL ANSELMO B AQUENTS C ALO D AMBOY C OWN B LOAMY SURFACE B GRAVELLY A ALOGIA C AMBRANT B ANDIC CRYUMBREPTS B SANDY SURFACE B LOAMY ALOHA C AMBRAW B/D BEDROCK STEEP B SALINE ALOMAX,STONY D AMELAR B SUBSTRATUM C ANSGAR B/D AQUEPTS D ALONA B AMELIA C ANDIC DYSTRIC ANSPING B AQUEPTS ALONEMILL B AMENE D EUTROCHREPTS B ANT FLAT C NONACID ALONSO B AMENIA B ANDIC DYSTROCHREPTS C DRY B AQUIC ARGIBOROLLS C ALONZEVILLE,COBBLY B AMENSON D ANDIC HAPLUMBREPTS B WARM D AQUIC CALCIORTHIDS D ALONZVILLE B AMERICANOS B ANDIC XEROCHREPTS B ANTEL B AQUIC CALCIORTHIDS C ALOVAR C AMERICUS A LOAMY C ANTELOPE SPRINGS C AQUIC CRYANDEPTS C ALPENA A AMERY B ANDIC XERUMBREPTS B LOAMY SUBSTRATUM D AQUIC CRYOBORALFS B ALPHA B AMES C/D BEDROCK ANTERO D AQUIC CRYOBORALFS D ALPIN A AMESHA B SUBSTRATUM C ANTHO B AQUIC CRYOBOROLLS C ALPINEPEAK C AMESHA C HIGH RAINFALL C ANTHO A AQUIC CRYOCHREPTS B ALPON B AMESMONT C ANDOK B ANTHOLOP D AQUIC CRYOFLUVENTS B ALPOWA B AMHERST D ANDOVER D ANTHONY B AQUIC CRYOFLUVENTS C ALPOWA C AMISTAD D ANDRADA D WET SUBSTRATUM D AQUIC CRYOFLUVENTS C WET C AMITY D ANDREGG B ANTIGO B AQUIC CRYUMBREPTS C ALROS,ALKALI C AMMON B ANDRES C ANTILON C AQUIC DYSTROCHREPTS C ALS A AMODAC C ANDREWS C ANTIOCH D AQUIC HAPLOBOROLLS C ALSASH B AMOLE A ANDRUSIA A ANTLER C AQUIC HAPLOHUMULTS D ALSCO B AMOR B ANDRY D ANTOINE B AQUIC ALSEA B AMORUS D ANDRY SERIES,DRAINED D ANTOKEN C HAPLOXEROLLS,PROT ALSPAUGH C AMOS C ANDYS B ANTONITO B ECTED D ALSTAD D AMOSTOWN C ANED D ANTONITO C AQUIC HAPLUSTOLLS C ALSTAD C AMPAD C ANELA B ANTOSA B AQUIC NATRARGIDS C ALSTAD C AMPAD B ANETH B ANTROBUS B AQUIC TORRIORTHENTS D MODERATELY WET C AMPHION C ANETH A ANTWERP C LACUSTRINE ALSTONY B AMSDEN B DRY A ANTY B SUBSTRATUM C ALSTOWN C AMSTERDAM B ANGELICA B/D ANUNDE B AQUIC UDIFLUVENTS C ALSUP C AMTOFT D ANGELINA D ANVIK B AQUIC UDIPSAMMENTS A ALTA B AMWELL C ANGELO C ANVIL,WET SUBSTRATUMC AQUIC USTIFLUVENTS C ALTAMONT D AMY D ANGELPEAK B ANWAY B AQUIC USTIFLUVENTS D ALTAPEAK B ANACAPA B ANGELUS B AOWA B AQUIC USTIFLUVENTS D ALTAR B ANACOCO D ANGELUS C APACHE D DRY B ALTAVISTA C ANACONDA B ANGIE C APAKUIE A SALINE D ALTDORF D MODERATELY WET C ANGIE D APALACHEE D AQUIC USTORTHENTS D ALTHOUSE B ANAHEIM C ANGLE A APALO B AQUIC XEROFLUVENTS C ALTICREST B ANAHEIM B ANGLEN C APAREJO B HIGH RAINFALL D ALTITA C ANAHUAC D ANGOLA C APELDORN D AQUILLA A ALTMAR B ANAMITE D ANGORA B APEX B AQUIMA B ALTO C ANAN D ANGOSTURA B APISHAPA D AQUINAS C ALTOGA C ANAPRA B COBBLY C COOL C AQUOLLS D ALTON A ANASAZI C STONY; BEDROCK APISON B AQUOLLS ALTUDA D ANATONE