(dissenting).
[¶ 22.] The majority opinion erroneously dismisses the medical testimony in this case based on perceived inconsistencies and a finding of suspect credibility. Schneider testified that “I had hit a snowdrift, or something of that nature, and I felt a sharp pain” while driving a snowplow on January 27, 1994. Schneider called his supervisor and told him that driving the plow was hurting his back and he could not continue. After making numerous stops because of the pain, he eventually completed his route and returned to the DOT garage. Schneider filed a report of injury which stated, “experienced a severe pain in lower back, left hip, left leg while driving truck to plow snow” that “occurred while driving truck to plow snow.” He has not worked since.
[¶ 23.] The Department denied benefits finding that:
1. Claimant’s credibility is questionable and suspect because of information he either supplied or failed to supply.
2. Claimant’s complaints of pain and physical disability were the same prior to January 27,1994, as thereafter.
[¶ 24.] The circuit court reversed the Department’s decision finding that:
1. The evidence is not disputed that claimant’s back condition became worse after the incident where he reported pain in the course of driving and operating the snowplow on January 27, 1994, as compared with the symptoms and physical conditions observed by his physical therapist prior to the January 27 injury.
2. The court does not rely on Schneider’s credibility in any way in finding that the claimant was diagnosed with only a bulging disk prior to January 27, 1994, when he was diagnosed with a free fragment that had completely left the disk space and was pressing on the nerve.
3. Subsequent to the snowplow incident on January 27, 1994, claimant has never been able to reach the level of improvement and recovery that he attained after his wood chopping injury.
4. The conclusion drawn by the Department ... is not supported by any substantial evidence.
The circuit court determined that a work related injury did occur and that the Department’s findings were not supported by substantial evidence or were clearly erroneous. The circuit court found that Schneider established that an aggravation of an old injury occurred, and remanded to the Department for an award of benefits.
[¶ 25.] It is incumbent upon Schneider to establish a causal relationship between his injury and his employment to collect workers’ compensation benefits. See Gilchrist v. Trail King Industries Inc., 2000 SD 68, ¶ 7, 612 N.W.2d 1, 2. This requirement does not mean that Schneider must show “that his employment was the proximate cause, direct, or sole cause of his injury; rather [he] must show that his employment was a ‘contributing factor’ to *732his injury.” Id. (citation omitted). “It is sufficient that the disability “was brought on by strain or overexertion incident to the employment, though the exertion or strain need not be unusual or other than that occurring in the normal course of employment.’ ” Tischler v. United Parcel Service, 1996 SD 98, ¶ 27, 552 N.W.2d 597, 603.
[¶ 26.] “The burden of proof is on [Schneider] to show by a preponderance of the evidence that some incident or activity arising out of his employment caused the disability on which the workers’ compensation claim is based.” Kester v. Colonial Manor of Custer, 1997 SD 127, ¶ 24, 571 N.W.2d 376, 381. This level of proof “need not arise to a degree of absolute certainty, but an award may not be based upon mere possibility or speculative evidence.” Id. To meet his degree of proof “a possibility is insufficient and a probability is necessary.” Maroney v. Aman, 1997 SD 73, ¶ 9, 565 N.W.2d 70, 73.
[¶ 27.] The Department erroneously found that no compensable injury occurred on January 27, 1994. The findings of fact entered by the Department were based on a finding of a lack of credibility. While giving due regard to the Department’s determination on credibility, I agree with the circuit court’s finding of error in the Department’s reasoning. The Department determined that Schneider lacked credibility because of his conflicting historical accounts of the injury and his inability to describe what occurred on January 27, 1994.
[¶ 28.] The record indicates that Schneider had difficulty relaying his history of back problems to medical providers. Yet, that finding does not defeat Schneider’s claim out-of-hand. Our inquiry is whether Schneider injured or aggravated a prior condition in the course of employment with the DOT. Tischler, 1996 SD 98, ¶ 28, 552 N.W.2d at 603. Schneider must demonstrate that “the strain of his employment was a contributing factor to his medical condition.” Schuck, 529 N.W.2d at 899.
[¶ 29.] In relation to the January 27, 1994 incident Schneider stated in his deposition that his back pain “just more or less started.” At the hearing, the following exchange occurred on cross-examination:
Q: Do you really know what happened? Can you point to anything specific that happened that day that caused your back pain to start?
A: It was the constant bounce, constant jar. The plow is moving. I had to have hit something or something because all of a sudden when my back and the leg pain, it shot to my toes.
Q: But you can’t remember anything in particular, can you?
A: Sir[,] as far as?
Q: Any incident that actually happened to bring on this back and leg pain?
A: Any incident?
Q: Any particular thing? You can’t really remember hitting anything with your truck or anything else, can you?
A: Yes, I can, sir, because I had to pull my truck over.
Q: At your deposition I asked you that question and I said, was there anything you can point to that brought that on, and I’m thinking of a particular incident. Your answer was I don’t understand that, sir. And I asked another question, I mean had you had something hit your leg? Had you bent over, had you lifted something, had your truck hit something, was there anything that seemed to cause it or did it just start? Your answer was it more or *733less started. That is how you answered the question then do you have a different recollection now about what happened?
A: All I know — I remember the sharp pain. I remember taking my truck to the side of the road, locking my air brakes, having my safety lights all on, which they would be on and I had to dismount my truck.
Based on a comparison of Schneider’s testimony at the hearing to his deposition testimony, the Department erroneously found that he lacked credibility.
[¶ 30.] The Department erred by utilizing this perceived inconsistency to dismiss evidence that Schneider’s condition was worsened by this incident. I acknowledge that “[i]t is incumbent upon the circuit court to be duly aware of the opportunity of the Department to judge at first hand the credibility of the witness.” Lends His Horse, 619 N.W.2d at 520. Yet, the majority opinion’s reliance on Lends His Horse is misplaced. Lends His Horse does not dictate that we reject out of hand a worker’s compensation claim when there is a finding of lack of credibility. While subjective experiences of pain are always at issue, the majority opinion forgets that so is medical evidence. The Department overlooked evidence relating to the accident report filed by Schneider, the worsening of Schneider’s medical condition, the medical testimony of Coleman who treated Schneider both before and after January 27, 1994, and Dr. Teuber’s opinion that driving the snowplow aggravated the condition.
[¶ 31.] When evidence on the issue of causation is submitted to the Department in deposition form “we review that testimony de novo and we are unhampered by the clearly erroneous rule.” Tischler, 1996 SD 98, ¶ 24, 552 N.W.2d at 602. “This means that we will decide for ourselves the credibility of the deponent and the weight and value to be attached to their testimony.” Id.
[¶ 32.] Dr. Teuber stated on deposition that he believed that an aggravation of the prior injury occurred while operating the snowplow after the wood-chopping incident. He stated that simply driving a snowplow could cause the type of movement that can aggravate a pre-existing disc problem. Additionally, Coleman stated on deposition that Schneider’s condition had become worse after January 27, 1994. He stated that it was probable there was an initiating event that aggravated this condition and it just does not happen on its own. Specifically, it was probable the work incident was the contributing factor 'to his current level of disability.
[¶ 33.] The testimony of the medical experts establishes that Schneider was initially diagnosed as suffering from a bulging disc. After January 27, 1994, the date of the snowplow incident, Schneider was diagnosed as experiencing a free-floating fragment in his back that required surgery. In addition, the testimony establishes that Schneider’s level of pain increased after the snowplow incident. As recognized by the trial court, “the evidence is not disputed that claimant’s back condition became worse after the incident where he reported pain in the course of driving and operating the snowplow on January 27, 1994, as compared with the symptoms and physical conditions observed by his physical therapist prior to the January 27 injury.” The Department was clearly erroneous in determining that Schneider’s complaints were unchanged after January 27,1994.
[¶ 34.] There was an adequate foundation for these medical opinions and the Department was clearly erroneous in determining that Schneider did not establish a causal connection between his employ*734ment and his injuries. The evidence produced at the hearing provided support that the operation of the snowplow was a contributing factor to this injury. I am definitely and firmly convinced a mistake has been committed and I dissent.
[¶ 35.] KONENKAMP, Justice, joins this dissent.