PANGANI BASIN WATER BOARD

throughout the year - rainfall
patterns on Mt. Kilimanjaro, which
lies immediately to the north of the
spring, appear to have no bearing
on its output (Røhr et al., 2002). In
Kenya, the Lumi River drains the
southern slopes of Mt. Kilimanjaro,
and is the main source of water to
Lake Jipe. Almost all of the river’s
discharge into the lake is derived
from springs (Musyoki, 2003).
About 5% of all the water used in the
PRB is derived from groundwater
sources. Boreholes yielding more
than 100 cubic metres per hour have
been drilled in the Kahe Plains while
boreholes yielding between 10 to 50
m3/h have been sunk in the Sanya
plains and Karoo Rocks of Tanga.
Groundwater recharge is mainly from
rainfall and rivers (Makule, n.d.).
As the Pangani leaves the Nyumba
ya Mungu Reservoir, the following
demands are placed upon it
(Mujwahuzi, 2001):
Box 6: Threats to the PRB’s water
and wetland resources
• By 2015, water demand within the Basin is expected
to double, while, at the same time, evidence of water
stress has been present since the 1940s.
• Principal areas for concern are increasing irrigation
and urban demands. In the case of irrigation, water
losses can be as high as 85%.
• As the number of water users increase, along with the
competition between them, the likelihood of conflict
between water users will also augment.
• The fisheries of the Nyumba ya Mungu (NYM)
Reservoir are said to be under considerable stress
due to over-fishing.
• Large portions of the largest wetland in the Basin – the
Kirua Swamp – have dried up as a result of the regulation
of water flows issuing from the NYM dam.
• Large nutrient inflows into Lake Jipe have encouraged
excessive papyrus and Typha growth that threatens
to overwhelm to lake.
Firm flow for power production..................................................24 m 3 /s
Irrigation.......................................................................................7m 3 /s
Domestic uses........................................................................1–2 m 3 /s
Total....................................................................................32–33 m 3 /s
Sarmett (pers. comm.) states, however, that the NYM is rarely able to release more than 22 m 3 /s.
The NYM Reservoir is the largest water body in the Basin. There are three others: Lake Ambussel, and,
lying on Tanzania’s border with Kenya, Lakes Chala and Jipe. These lakes feature prominently in the
irrigation and hydrological planning of Kenya’s Taita-Taveta District, in which they lie. Lake Jipe’s water
level and surface area vary substantially with rainfall. Thus, its surface area varies from 18 km 2 (1954)
to 28 km 2 (1947), while the amount of water contained within it varies from 20 to 60 MCM (Musyoki and
Mwandotto, 1999). Within the Kenyan portion of Lake Jipe’s catchment lies part of Tsavo West National
Park, 48.5 km 2 of swamp, 435 km 2 of sisal estates and 196.5 km 2 of what is described as ‘public land’
set aside for the Lake Jipe Settlement Scheme (Musyoki and Mwandotto, 1999). An estimated 300,000
tonnes of silt are washed into the lake annually (Musyoki, 2003).
Lake Chala lies in a small volcanic crater on Mt. Kilimanjaro’s southern slopes. It is between 85 and 90 m.
deep, and covers a surface area of about 3.15 km 2 . It contains between 300 - 350 MCM of water (Musyoki
and Mwandotto, 1999). Its water quality is very good, and for this reason is being considered a source for
Kenya’s growing coastal urban areas. Projected future abstraction rates are for 7 MCM annually (Musyoki,
2003). Its elevated situation means that water may be conveyed by gravity to its destination.
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