All rights-of-way granted under the regulations in this part 169 shall be in the nature of easements for the periods stated in the conveyance instrument. Except as otherwise determined by the Secretary and stated in the conveyance instrument, rights-of-way granted under the Act of February 5, 1948 (62 Stat. 17; 25 U.S.C. 323-328), for railroads, telephone lines, telegraph lines, public roads and highways, access roads to homesite properties, public sanitary and storm sewer lines including sewage disposal and treatment plants, water control and use projects (including but not limited to dams, reservoirs, flowage easements, ditches, and canals), oil, gas, and public utility water pipelines (including pumping stations and appurtenant facilities), electric power projects, generating plants, switchyards, electric transmission and distribution lines (including poles, towers, and appurtenant facilities), and for service roads and trails essential to any of the aforestated use purposes, may be without limitation as to term of years; whereas, rights-of-way for all other purposes shall be for a period of not to exceed 50 years, as determined by the Secretary and stated in the conveyance instrument. [37 FR 12937, June 30, 1972. Redesignated at 47 FR 13327, Mar. 30, 1982]