The drainage district shall have power to purchase such real estate or easement therein as it may need, and if it cannot agree on the purchase price of any needed real estate or easement therein, it shall have power to condemn the same whether the property be within the limits of such district or outside its boundaries. The exercise of the right of eminent domain on areas outside the boundaries of the district shall be limited only to those projects which have been approved by the Department of Natural Resources. This limitation shall not apply to any drainage district subject to the supervision of the United States Army Corps of Engineers. The procedure to condemn property shall be exercised in the manner set forth in sections 76-704 to 76-724. If such drainage district finds it expedient or necessary for the maintenance of any part of its improvement already constructed to add thereto further construction in the nature of a settling basin into which waters will be permitted to flow for the purpose of dropping silt before finding their outlet into any part of the main or lateral ditches of such drainage district improvement, such drainage district, if not able to agree with the landowner on the yearly cash rental of any premises taken and used for such purpose, shall have the right to condemn for the purpose of fixing the yearly rental for the land so taken. If such drainage district takes or damages any real estate of any minor or protected person, the guardian or conservator of such minor or protected person may agree and settle with the drainage district for all damages or claims by reason of taking such real estate or easement and may give valid releases and discharges therefor.