"The drying-up of the river, which should be at its highest point at the end East Africa's long rainy season, is one of a series of ominous signs that conservationists believe could add up to an ecological disaster.
The sun-scorched boulders that ring the shore of Kenya's Lake Baringo are cut by a sharp brown line, running horizontally, that shows the watermark of the past. Beneath the dark divide is an expanse of white stone freshly bared to the elements as the lake has receded dramatically.
A report released last week by Kenya's Water Resource Management Authority has dismissed any hopes that these phenomena could be unrelated.
In the report, Simon Mwangi, the authority's Rift Valley regional technical manager, said that the River Perkerra, which feeds Lake Baringo, and the Malewa which drains into Lake Naivasha, were at their lowest levels on record.
The picture was similarly bleak, he reported, with the Ewaso Nyiro and Mara rivers. The country's great lakes from Turkana in the north to Nakuru, and the economically vital Naivasha, home to Kenya's flower industry, were also alarmingly low.
The answer to the riddle of the Mara's dwindling waters, and the general drought conditions, lies upstream, in the Mau forest.
The Mara river originates on the Mau escarpment, eventually draining into Lake Victoria. The largest remaining forest in Kenya, Mau functions as a water tower for the East African country, feeding rivers and helping to regulate rainfall.
However shocking reports this year have a revealed that the eco-system is under siege from illegal loggers and land-grabbing farmers, as well as large and small recipients of political patronage. Many of those are smallholders receiving parcels of the forest as "land for votes", while Kenya's Daily Nation newspaper named two of the children of former president Daniel arap Moi as among the bigger owners.
There effect is a devastating fragmentation of what environmentalists call an ecological utility whose services stretch from watering Kenya's tea estates to feeding the rivers powering its hydroelectric plants, and regulating temperature and rainfall throughout an often arid land. Despite being home to the headquarters of the United Nations Environment Programme, Kenya has systematically ignored warnings over the importance of conserving the Mau forest. While the troubled coalition government in Nairobi has belatedly begun to recognise the problem, it has so far done next to nothing about it."