This is the enactment which mandates compulsory registration of Marriages in Uttarakhand u/s

3. (1) Notwithstanding anything contained in any other law for the time being in force of in any custom or usage to the contrary, all the marriages solemnized in the State after the commencement of this Act shall be registered within ninety days of solemnization of marriage in such manner as may be prescribed.

Index of all Acts and Rules are here.