- Why it is forbidden to water even an irrigated field with water from a pool of rainwater
The Mishnah on Daf 2a had stated regarding watering even an irrigated field on Chol HaMoed, אבל לא ממי הגשמים וממי הקילון – But one may not water from a pool of rainwater nor from the water of a well. The Gemara here asks, that while it is understandable that one cannot use water from a well because there is טירחא יתירא – excessive effort, why is it not permitted to use water from a pool of rainwater since there is no excessive effort? Rebbe Ill’a said in the name of Rebbe Yochanan: גזירה מי גשמים אטו מי קילון – It is a decree on rainwater because of water from a well. Rashi explains that people might come to draw water from a well. Rav Ashi said: מי גשמים גופייהו לידי מי קילון אתו – The rainwater itself will become like water from the well, in that it will eventually require a pail. Rashi explains that as the water is used the water level will go down, and a person will need to draw the water with a pail. The Gemara clarifies that Rebbe Yochanan and Rav Ashi disagree regarding what Rebbe Zeira taught, that נהרות המושכין מים מן האגמים מותר להשקות מהן בחולו של מועד – With streams that draw water from ponds containing rainwater, one is permitted to draw from them on Chol HaMoed. Rav Ashi holds of Rebbe Zeira’s view, since in this case there is no fear of the water level dropping, and Rebbe Yochanan does not, and holds that there was a decree that one may come to use a pail.
- Why one may not dig out a new irrigation canal on Sheviis
The Mishnah had stated: Rebbe Elazar ben Azaryah says: אין עושין את האמה בתחילה במועד ובשביעית – One may not dig out a new irrigation canal on Chol HaMoed or during Sheviis. The Gemara asks, that while it is understandable that it is prohibited to do so on Chol HaMoed because of tircha, why is it prohibited during Sheviis, when there is no concern for tircha? Rebbe Zeira and Rebbe Abba bar Mammal disagree on the reason. One says, מפני שנראה כעודר – because it appears as if the person is hoeing, and the other one says, מפני שמכשיר אגפיה לזריעה – because he is making the canal’s banks suitable for sowing. Rashi explains that the dug-up earth is now soft. The Gemara seeks the practical difference between the two opinions and concludes that they would differ in a case where one takes the earth from the canal and throws it far away from the banks of the canal. In this case, there is no concern according to the one holds that the issue is preparing the banks for sowing, while it is still forbidden according to the one who holds that the issue is hoeing.
- ומתקנין את המקולקלת במועד
The Mishnah stated: ומתקנין את המקולקלת במועד – One may fix a damaged irrigation canal during Chol HaMoed. The Gemara asks what is considered damaged, and Rebbe Abba said: שאם היתה עמוקה טפח מעמידה על ששה טפחים – It means that if the canal is now one tefach deep, it may be restored to a depth of six tefachim. The canal is called an amah because an amah is six tefachim. The Gemara asks what would be the din if one wanted to restore a canal that is two tefachim deep to its original depth of seven tefachim? Do we say that here too it is permitted because he is also digging five tefachim, or do we say that since there is an additional tefach that is not necessary for the workings of the canal, איכא טירחא טפי – there is too much exertion, and it is prohibited? The Gemara leaves it as a teiku.