ðə dɹˈeɪnɪdʒ bˈeɪsən ʌvðə jˈæmæskə mˈɛʒɚz ; ɪts ˈævɹɪdʒ dˈɛbɪt æt ðɪ ˈɛnd ɪz ʌv , ðɪs ɪz kənsˈɪdɚd ɹˈɛlətˌɪvli slˈoʊ kəmpˈɛɹd tə ɹˈɪtʃɪljˌuː æt ænd sˈeɪntfɹˈænswɑː æt ɹˈɪvɚz, ðə nˌɪɹɪst stɹˈiːmz; ɪɾ ɪz haʊˈɛvɚ sˈʌbdʒɛkt tə sˈiːzənəl flˌʌktʃuːˈeɪʃənz wɪð ɐ ɹˈɛkɚd flˈoʊ ʌv ɪnðə spɹˈɪŋ lˈɪŋkt tə ðə snˈoʊmɛlt ænd ɪnðə fˈɔːl kˈɔːzd baɪ pɹɪsˌɪpɪtˈeɪʃən, ænd mˈɪnɪməmz ʌv ɪn wˈɪntɚ ænd sˈʌmɚ.
The drainage basin of the Yamaska measures ; its average debit at the end is of , this is considered relatively slow compared to Richelieu at  and Saint-François at  rivers, the nearest streams; it is however subject to seasonal fluctuations (with a record flow of  in the spring (linked to the snowmelt) and in the fall (caused by precipitation), and minimums of  in winter and summer.