The River Lumi (also Lomi or Luffu) is located in Rombo District, Kilimanjaro in northereast Tanzania and a small part in southern Kenya in Coast Province.

It originates on the east side of Mawenzi peak on the east side of (Mount Kilimanjaro), and flows so close to the River Rombo as almost to form a fork.

The Lumi, however, maintains its southerly direction, and may thus be said to represent the upper course of the Ruvu, one of tho two main sources of the Pangani River.

[2] After the building of several dams along the Kenyan side of the Lumi, and with several periods of reduced rainfall, the dry up of Lake Jipe became a concern, necessitating wetland management programs.

[3] During the period of 2004–2006, the United Nations Development Programme GEF Small Grants Programme and the Biodiversity Conservation Programme of the European Union have completed a de-siltation and restoration project of the river's original course.