as futile as trying to fill a well with snow ❍ 纳下表章不奏，只是行移邻近州府， 催趱各处径调军马， 前去策应， 正如～一般。(《水浒全传》1012) They decided not to forward the petitions. They only notified a few neighboring prefectures and urged them to send reinforcements and relief. This was as futile as trying to fill a well with snow.
担雪填井dān xuě tián jǐnɡ
用雪去填井。比喻做无用功，白费力气。pour water into a sieve,plough the air, work in vain