Idaho Code § 7-712: Damages — Date of accrual.

For the purpose of assessing compensation and damages, the right thereto shall be deemed to have accrued at the date of the summons, and its actual value, at that date, shall be the measure of compensation for all property to be actually taken, and the basis of damages to property not actually taken, but injuriously affected, in all cases where such damages are allowed, as provided in the last section. No improvements put upon the property subsequent to the date of the service of summons shall be included in the assessment of compensation or damages. The compensation and damages awarded shall draw lawful interest from the date of the summons.