Mangrove Mountain was established in the late 1800s by families from Mangrove Mountain Creek moving to land “on the Mountain” as well as from the Gosford area to the east. Mangrove Mountain Public School opened as a half-time school with Island Flat operating from September 1895 until February 1902 and again from May 1912 until June 1915. Then as a provisional school from August 1915 until December 1917 and as a public school from January 1918 until closure in December 1978. The school was known as Blood Tree until March 1896 and as Koree from then until February 1937. The original site is now on the Northern side of the Mangrove Mountain Reserve and the name lives on as the name adopted for the Koree Girl Guides cabin. This is located on the other side of Popran Creek, further to the North on Wisemans Ferry Road. Mangrove Dam was major project in the area in the 1980s to build a dam for the supply of water to Gosford and Wyong.
The dam is 80m (260′) high with a crest length of 380m (1,200′) and a storage capacity of 190,000ML (about 30% of the capacity of Sydney Harbour). It is composed of about 1.2M cubic metres of rolled, soft sandstone from the Narabeen Group of sandstones and siltstones. The embankment also contains about 100,000 cubic metres of processed basalt from quarries at Kulnura and Peats Ridge. The face contains about 13.500 cubic metres of concrete and covers an area of about 30,000 square metres. Below on the left is a rare photograph of the dam taken during construction in 1981: the area to the right is all under water now. On the right is a photograph of the completed dam taken in May 1986:
There is more information about Mangrove Dam here.