Okla. Stat. tit. 68, § 1805

On or prior to the first day of May, 1943, and on or before the first day of March of each succeeding year, each such cooperative shall file with the Oklahoma Tax Commission, on forms prescribed by said Commission, a statement of the total number of miles of line of such cooperative, owned, maintained, and operated by such cooperative, in each county and school district of the state as of January first of each year; and each such cooperative shall likewise file a statement of the total number of miles of line owned, maintained, and operated as of January first of each year within each school district of each county with the county treasurer of each county.