[If] one was standing in prayer and he remembered that he is a baal keri, he should not stop [praying]; rather, he should shorten [his prayer]. [If] he went down to immerse [in a mikveh]: If he is able to go up [from the mik-veh], cover himself, and recite [the Shema] before sunrise, he should go up, cover himself, and recite [it]. But if not, he should cover himself with the water and recite [the Shema]. But he may not cover himself with foul water, nor with water used for soaking [flax], un-less he pours [clean] water into [it]. And how far must he distance himself from [it] and from excrement? Four amos.