from the provinces of New Zealand. To unify all rail systems operating in the colony, and to ease the cost of construction, the national rail gauge was set at a narrow gauge of . The Bluff Branch was converted to this gauge in a single day, 18 December 1875. The original standard gauge locomotives and rolling stock retreating to the Bluff wharf and then loaded onto the Cezarewitch and sent to New South Wales, although the locomotives and rolling stock never made it, being wrecked at Big Bay, West Coast. Mokomoko Harbour Branch During the construction phase of the Bluff Branch, contractors found that landing urgent supplies at the Invercargill wharf could prove difficult due to the worsening danger of the New River estuary silting up dangerous sand bars. Contractors were having a difficult time building over and around the upper reaches of the estuary and getting equipment into the area proved troublesome. At the mouth of the estuary was the moderately deep and weather sheltered entry to the Mokomoko inlet. A Jetty already existed at the eastern side of the inlet entrance for the local settlers and at one point was promoted as an alternative to both Campbelltown and Invercargill's port ambitions. It was decided to lay a spur line off the still incomplete Bluff mainline to the jetty which consisted of a large curve that required deep drains on each side. The junction points faced Awarua with a small flag station controlling the points. The branch was only ever useful as a supply line and few passengers were carried, mainly from the small coastal steamers that would land at the jetty instead of risking the voyage up to Invercargill. When the new wharf at Bluff Harbour opened, the Mokomoko jetty fell into disuse. The railway remained until a change of gauge day on 18 December 1875 when it was decided to close the line instead of re-gauging it. The rails were taken up and used elsewhere. Thanks to the well-built drain canals on each side of the formation, the original route is still visible and easily traced on Google Earth as a large curve leading to the old jetty, in which piles still remain. Operation Bluff established itself as the port of Southland and the line has always been busy with both inbound and outbound freight. Major railway facilities were built around the original town wharf site with