An investigation into some water Quality problems of lake Kanyaboli in Kenya
Abstract
This study attempted an investigation into some water quality
problems of Ltke Kanyaboli. The geographical location of lake
Kanyaboli wlthin the Yala swamp and its size of lO.5km' make it
ideal for this investigation. Further the problem is complicated
by the fact that the lake has no outlet and after the diversion of
river Yala during the reclamation of the Yala swamp, there is no
major inlet into this lake. On the whole it is assumed that the
activities around the lake in addition to the hydro-technical
measures that has taken place within the swamp have a direct impact
on water quality of the lake.
This study therefore intended to assess the levels of various
parameters in the lake water as well as their pathways. Because
the lake lacks an outlet, a unified approach that integrates water
quality parameters and that of interstitial water was preferred.
Both water samples and bottom sediments were collected and
laboratory analysis performed on parameters for both surface water
and interstitial water respectively.
Results show that the levels of ionic constituents are low,
suggesting that this is due to the low solubility of the
precambrian rocks within the·catchment. On the other hand iron and
manganese are reported in levels that are almost equal to or above
the recommended levels. Most of the normal water characteristics
reflect that lake Kanyaboli is a fresh (TDS), soft (hardness) and
an alkaline lake (pH). However col~ur and turbidity are elevated.
Precipitation and runoff contribute significant amount of
pollution parameters as shown .by the results, implying that
catchment activities have an important influence on the quality of
the lake water. While phosphorus has not been detected in water,
nitrates occurred only in trace amounts. The leve~s of nitrites,
ammonium nitrogen, free ammonia and albuminoid ammonia (O.06mg/l,
O.12mg/l, O.06mg/l and O.06mg/l respectively) suggest organic
contaminat ion. Permanganate value (4.04mg/l) implies a large
,
iv
amount of organic matter. The levels of the above nutrients are
elevated in interstitial water and those of nitrates and phosphorus
(0.12mg/l and 1.12mg/l respectively) suggest that the lake is
eutrophic. Generally the levels of the parameters is higher in
interstitial water than in overlying water (except pH and nitrites)
suggesting that pollutants are accumulated in the bottom sediments.
ThlS therefore is a pointer to the fact that these pollutants have
accumulated in the bottom sediments and thus sediments may act as
source of these pollutants at certain periods of time and under
certain prevailing conditions.
Prevention of further pollution appears as the only means of
attaining the objective of managing the lake water. From the
viewpoint of water quality management, Lake kanyaboli can be used
as an experimental lake in the study of water quality and thus
scientific knowledge of great value in controlling pollution may
result. Above all, if proper management techniques can be achieved
for this small lake, then the lake Kanyaboli example can be applied
in other similar situation within the country as the nation faces
the need for managing this aspect of its water resource.
Sponsorhip
The University of nairobiPublisher
Department of sociology