The following Oregon Administrative Rules outline the role of county government in preventing "significant change in accepted farm practices or a significant increase in the cost of farm practices" by imposing "clear and objective conditions" on the siting of these utilities.
OAR 660-033-0010 Division 33 Agricultural Lands
http://arcweb.sos.state.or.us/rules/OARS_600/OAR_660/660_033.html
(you've read this language before in ORS 215.275; especially note paragraph (d) and(17) below)
(16)(a) A utility facility is necessary for public service if the facility must be sited in an exclusive farm use zone in order to provide the service. To demonstrate that a utility facility is necessary, an applicant must show that reasonable alternatives have been considered and that the facility must be sited in an exclusive farm use zone due to one or more of the following factors:
(A) Technical and engineering feasibility;
(B) The proposed facility is locationally dependent. A utility facility is locationally dependent if it must cross land in one or more areas zoned for exclusive farm use in order to achieve a reasonably direct route or to meet unique geographical needs that cannot be satisfied on other lands;
(C) Lack of available urban and nonresource lands;
(D) Availability of existing rights of way;
(E) Public health and safety; and
(F) Other requirements of state and federal agencies.
(b) Costs associated with any of the factors listed in subsection (16)(a) of this rule may be considered, but cost alone may not be the only consideration in determining that a utility facility is necessary for public service. Land costs shall not be included when considering alternative locations for substantially similar utility facilities and the siting of utility facilities that are not substantially similar.
(c) The owner of a utility facility approved under this section shall be responsible for restoring, as nearly as possible, to its former condition any agricultural land and associated improvements that are damaged or otherwise disturbed by the siting, maintenance, repair or reconstruction of the facility. Nothing in this subsection shall prevent the owner of the utility facility from requiring a bond or other security from a contractor or otherwise imposing on a contractor the responsibility for restoration.
(d) The governing body of the county or its designee shall impose clear and objective conditions on an application for utility facility siting to mitigate and minimize the impacts of the proposed facility, if any, on surrounding lands devoted to farm use in order to prevent a significant change in accepted farm practices or a significant increase in the cost of farm practices on surrounding farmlands.
(17) A power generation facility shall not preclude (exclude) more than 12 acres from use as a commercial agricultural enterprise unless an exception is taken pursuant to OAR chapter 660, division 4.
(It seems to me that related distribution facilities (transmission lines) should not take more land (12 acres) out of production than a commercial agricultural enterprise "power generation facility" would under the above OAR.)
If you're confused on what an "energy facility" is, it's because ORS Chapter 469, the State of Oregon refers to both power generation facilities and high voltage transmission lines as "energy facilities": http://www.leg.state.or.us/ors/469.html
(11)(a) “Energy facility” means any of the following:
(A) An electric power generating plant with a nominal electric generating capacity of 25 megawatts or more, including but not limited to:
(i) Thermal power; or
(ii) Combustion turbine power plant.
(B) A nuclear installation as defined in this section.
(C) A high voltage transmission line of more than 10 miles in length with a capacity of 230,000 volts or more to be constructed in more than one city or county in this state. . .
