Is a settlement valid for irrigation from a river or channel based on necessity?

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The settlement for irrigation from a person's river or channel is likely permissible because necessity compels it. Water is generally something for which compensation is allowed, as evidenced by taking compensation for water collected in a waterskin or container. A settlement is permissible even regarding matters whose sale is impermissible, as shown by the permissibility of settling for intentional bloodshed and similar cases, and settling regarding an unknown quantity.