Lowell Police Department issued the following announcement on Jan 24.
ATTENTION CITY OF LOWELL RESIDENTS!
Per local ordinance, you have 24 hours after the last snow fall to clear your sidewalk of snow and ice.
Please be a great neighbor or business and clear your sidewalk of snow and ice. It is a lot easier when it has not been packed down.
Thank you for your cooperation!
Sec. 19-46. - Sidewalks and areas to be cleared.
(a) No occupant of any premises or owner of premises or property shall fail to keep the sidewalks in front of or adjacent to such premises or property clear of ice and/or snow, to facilitate pedestrian use. Where there are no sidewalks, no such occupant or owner shall fail to clear a path free from snow and ice when such path will provide an extension of existing sidewalk on an adjacent property. Such path shall be the width of the existing adjacent sidewalk.
(b) Whenever any snow or ice has fallen or accumulated, it shall be cleared within twenty-four (24) hours.
(Ord. No. 86-1, § I, 10-20-86; Ord. No. 13-02 , § 6, 7-1-13)
Original source can be found here.