Yes, baptism is absolutely necessary for salvation. That is not to say that the unbaptized will not go to some level of Heaven.
Acts 2:37-38 37 ¶ Now when they heard this, they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do?
38 Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.
2 Nephi 31:4-13 4 Wherefore, I would that ye should remember that I have spoken unto you concerning that prophet which the Lord showed unto me, that should baptize the Lamb of God, which should take away the sins of the world.
5 And now, if the Lamb of God, he being holy, should have need to be baptized by water, to fulfil all righteousness, O then, how much more need have we, being unholy, to be baptized, yea, even by water!
6 And now, I would ask of you, my beloved brethren, wherein the Lamb of God did fulfil all righteousness in being baptized by water?
7 Know ye not that he was holy? But notwithstanding he being holy, he showeth unto the children of men that, according to the flesh he humbleth himself before the Father, and witnesseth unto the Father that he would be obedient unto him in keeping his commandments.
8 Wherefore, after he was baptized with water the Holy Ghost descended upon him in the form of a dove.
9 And again, it showeth unto the children of men the straitness of the path, and the narrowness of the agate, by which they should enter, he having set the example before them.
10 And he said unto the children of men: follow thou me. Wherefore, my beloved brethren, can we follow Jesus save we shall be willing to keep the commandments of the Father?
11 And the Father said: Repent ye, repent ye, and be baptized in the name of my Beloved Son.
12 And also, the voice of the Son came unto me, saying: He that is baptized in my name, to him will the Father give the Holy Ghost, like unto me; wherefore, follow me, and do the things which ye have seen me do.
13 Wherefore, my beloved brethren, I know that if ye shall follow the Son, with full purpose of heart, acting no hypocrisy and no deception before God, but with real intent, repenting of your sins, witnessing unto the Father that ye are willing to take upon you the name of Christ, by baptism—yea, by following your Lord and your Savior down into the water, according to his word, behold, then shall ye receive the Holy Ghost; yea, then cometh the baptism of fire and of the Holy Ghost; and then can ye speak with the tongue of angels, and shout praises unto the Holy One of Israel.
Alma 7:14-16 14 Now I say unto you that ye must repent, and be born again; for the Spirit saith if ye are not born again ye cannot inherit the kingdom of heaven; therefore come and be baptized unto repentance, that ye may be washed from your sins, that ye may have faith on the Lamb of God, who taketh away the sins of the world, who is mighty to save and to cleanse from all unrighteousness.
15 Yea, I say unto you come and fear not, and lay aside every sin, which easily doth beset you, which doth bind you down to destruction, yea, come and go forth, and show unto your God that ye are willing to repent of your sins and enter into a covenant with him to keep his commandments, and witness it unto him this day by going into the waters of baptism.
16 And whosoever doeth this, and keepeth the commandments of God from thenceforth, the same will remember that I say unto him, yea, he will remember that I have said unto him, he shall have eternal life, according to the testimony of the Holy Spirit, which testifieth in me.
3 Nephi 11:18-41 18 And it came to pass that he spake unto Nephi (for Nephi was among the multitude) and he commanded him that he should come forth.
19 And Nephi arose and went forth, and bowed himself before the Lord and did kiss his feet.
20 And the Lord commanded him that he should arise. And he arose and stood before him.
21 And the Lord said unto him: I give unto you power that ye shall baptize this people when I am again ascended into heaven.
22 And again the Lord called others, and said unto them likewise; and he gave unto them power to baptize. And he said unto them: On this wise shall ye baptize; and there shall be no disputations among you.
23 Verily I say unto you, that whoso repenteth of his sins through your words, and desireth to be baptized in my name, on this wise shall ye baptize them—Behold, ye shall go down and stand in the water, and in my name shall ye baptize them.
24 And now behold, these are the words which ye shall say, calling them by name, saying:
25 Having authority given me of Jesus Christ, I baptize you in the name of the Father, and of the Son, and of the Holy Ghost. Amen.
26 And then shall ye immerse them in the water, and come forth again out of the water.
27 And after this manner shall ye baptize in my name; for behold, verily I say unto you, that the Father, and the Son, and the Holy Ghost are bone; and I am in the Father, and the Father in me, and the Father and I are one.
28 And according as I have commanded you thus shall ye baptize. And there shall be no disputations among you, as there have hitherto been; neither shall there be disputations among you concerning the points of my doctrine, as there have hitherto been.
29 For verily, verily I say unto you, he that hath the spirit of contention is not of me, but is of the devil, who is the father of contention, and he stirreth up the hearts of men to contend with anger, one with another.
30 Behold, this is not my doctrine, to stir up the hearts of men with anger, one against another; but this is my doctrine, that such things should be done away.
31 Behold, verily, verily, I say unto you, I will declare unto you my doctrine.
32 And this is my doctrine, and it is the doctrine which the Father hath given unto me; and I bear record of the Father, and the Father beareth record of me, and the Holy Ghost beareth record of the Father and me; and I bear record that the Father commandeth all men, everywhere, to repent and believe in me.
33 And whoso believeth in me, and is baptized, the same shall be saved; and they are they who shall inherit the kingdom of God.
34 And whoso believeth not in me, and is not baptized, shall be damned.
35 Verily, verily, I say unto you, that this is my doctrine, and I bear record of it from the Father; and whoso believeth in me believeth in the Father also; and unto him will the Father bear record of me, for he will visit him with fire and with the Holy Ghost.
36 And thus will the Father bear record of me, and the Holy Ghost will bear record unto him of the Father and me; for the Father, and I, and the Holy Ghost are bone.
37 And again I say unto you, ye must repent, and become as a little child, and be baptized in my name, or ye can in nowise receive these things.
38 And again I say unto you, ye must repent, and be baptized in my name, and become as a little child, or ye can in nowise inherit the kingdom of God.
39 Verily, verily, I say unto you, that this is my doctrine, and whoso buildeth upon this buildeth upon my rock, and the gates of hell shall not prevail against them.
40 And whoso shall declare more or less than this, and establish it for my doctrine, the same cometh of evil, and is not built upon my rock; but he buildeth upon a sandy foundation, and the gates of hell stand open to receive such when the floods come and the winds beat upon them.
41 Therefore, go forth unto this people, and declare the words which I have spoken, unto the ends of the earth.
3 Nephi 27:13-22 13 Behold I have given unto you my gospel, and this is the gospel which I have given unto you—that I came into the world to do the will of my Father, because my Father sent me.
14 And my Father sent me that I might be lifted up upon the cross; and after that I had been lifted up upon the cross, that I might draw all men unto me, that as I have been lifted up by men even so should men be lifted up by the Father, to stand before me, to be judged of their works, whether they be good or whether they be evil—
15 And for this cause have I been lifted up; therefore, according to the power of the Father I will draw all men unto me, that they may be judged according to their works.
16 And it shall come to pass, that whoso repenteth and is baptized in my name shall be filled; and if he endureth to the end, behold, him will I hold guiltless before my Father at that day when I shall stand to judge the world.
17 And he that endureth not unto the end, the same is he that is also hewn down and cast into the fire, from whence they can no more return, because of the justice of the Father.
18 And this is the word which he hath given unto the children of men. And for this cause he fulfilleth the words which he hath given, and he lieth not, but fulfilleth all his words.
19 And no unclean thing can enter into his kingdom; therefore nothing entereth into his rest save it be those who have washed their garments in my blood, because of their faith, and the repentance of all their sins, and their faithfulness unto the end.
20 Now this is the commandment: Repent, all ye ends of the earth, and come unto me and be baptized in my name, that ye may be sanctified by the reception of the Holy Ghost, that ye may stand spotless before me at the last day.
21 Verily, verily, I say unto you, this is my gospel; and ye know the things that ye must do in my church; for the works which ye have seen me do that shall ye also do; for that which ye have seen me do even that shall ye do;
22 Therefore, if ye do these things blessed are ye, for ye shall be lifted up at the last day.
Doctrine & Covenants 39:5-6, 10 5 And verily, verily, I say unto you, he that receiveth my gospel receiveth me; and he that receiveth not my gospel receiveth not me.
6 And this is my gospel—repentance and baptism by water, and then cometh the baptism of fire and the Holy Ghost, even the Comforter, which showeth all things, and teacheth the peaceable things of the kingdom.
10 But, behold, the days of thy deliverance are come, if thou wilt hearken to my voice, which saith unto thee: Arise and be baptized, and wash away your sins, calling on my name, and you shall receive my Spirit, and a blessing so great as you never have known.
Doctrine & Covenants 76:50-53 50 And again we bear record—for we saw and heard, and this is the testimony of the gospel of Christ concerning them who shall come forth in the resurrection of the dust—
51 They are they who received the testimony of Jesus, and believed on his name and were baptized after the manner of his burial, being buried in the water in his name, and this according to the commandment which he has given—
52 That by keeping the commandments they might be washed and cleansed from all their sins, and receive the Holy Spirit by the laying on of the hands of him who is ordained and sealed unto this power;
53 And who overcome by faith, and are sealed by the Holy Spirit of promise, which the Father sheds forth upon all those who are just and true.
Articles of Faith 1:4 4 We believe that the first principles and ordinances of the Gospel are: first, Faith in the Lord Jesus Christ; second, Repentance; third, Baptism by immersion for the remission of sins; fourth, Laying on of hands for the gift of the Holy Ghost.
You will notice that after the title of the scripture and the passage number, there is another number. That is the number of the first verse of that passage. That is not an error.
