Journal of Water Resource and Protection, 2013, 5, 743-746
http://dx.doi.org/10.4236/jwarp.2013.57075 Published Online July 2013 (http://www.scirp.org/journal/jwarp)
Managing Eutrophication in Nigeria Inland Waters
N. O. Erhunmwunse*, A. R. Dirisu, A. E. Ogbeibu
Department of Animal and Environmental Biology, Faculty of Life Sciences,
University of Benin, Benin City, Nigeria
Received April 19, 2013; revised May 20, 2013; accepted June 15, 2013
Copyright © 2013 N. O. Erhunmwunse et al. This is an open access article distributed under the Creative Commons Attribution Li-
cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Recently in Nigeria, cultural eutrophication is on the increase in water bodies. Observations from land use around riv-
erine areas are predominantly for farmland and explain the high level of phosphate from runoff during the rainy season.
Increased siltation, deforestation, flooding, lumbering activities and other land use perturbation are among the causes of
eutrophication. Aquatic animals usually suffer hypoxia and anoxia and the anesthetic quality of water for recreational
activities, like swimming, boating and picnic is reduced. The Federal Ministry of environment (FMENV) and River
Basin Authority of Nigeria should ensure that all those involved in effluent discharge into water bodies follow the es-
tablished frame work and existing guidelines. Point source an d non-point sources of pollutio n should be monitored and
the adoption of mathe matic model which describes the overall nutrient ru noff and the catchment model suitable fo r de-
scribing the overall transport of water and nutrient through the river basin should be encouraged as practiced in Poland.
Keywords: Eutrophication; Nigeria Waters; Pollution; Mathematical Model; Nutrient Management
1. Introduction
Eutrophication is a natural process whereby lakes, estu-
aries and slow-moving streams receive excess nutrients
as a consequence of weathery of rocks and soil from the
surrounding water shed [1]. The increased nutrient (ni-
trogen and phosphorus) leads to an increased growth of
aquatic plants and organic production of the water body.
[2] states that it takes thousands of years on the time
scale for a water body (Oligotrophic) to turn into eutro-
phic water body through a natural process based on the
nature of entrusted minerals and the rate of watershed
weathering [1]. Although there is no single definition of
eutrophication, certain parameters have been considered.
In defining such phenomenon, [3] used phosphorus con-
centration, while [4] used the relationship between min-
eralized and production. Eutrophication is a threat to the
water quality of rivers, lakes and reservoirs, hence their
classification into oligotrophic, mesotrophic and eutro-
phic based on level of eutrophication [5].
Recently in Nigeria eutrophication rates in water bodies
have increased dramatically as a result of alterations in
nutrient cycles related to land use (Anthropogenic activi-
ties). The increasing demand for food and food insecurity
which has the increased use of fertilizers on farmland has
been pointed out as contributing over 80% of eutrophica-
tion of water bodies’ worldwide.
Cases of observed eutrophication in waters are on the
increase as a result of domestic and industrial discharges
into surface water bodies which vary in nature and qual-
ity thereby contributing significantly to chemical, bio-
logical and physical pollution of these water bodies [6].
Eutrophication may result if sufficiently large amount of
nutrients through wastes are added over a long period to
surface waters [7]. At the same time, siltation resulting
from blockage or basal river flow with erection of a bar-
ricade to mimic water fall for improved water flow may
enhance nutrient accumulation in certain sections of the
river creating a eutrophic environment [8].
Domestic, agricultural and industrial effluence and
waste discharge into rivers is a reason for the high pollu-
tion of water in the state [9]. Murdoch et al. [10] argues
that high level of phosphate and nitrate can lead to eu-
trophication, which increases algae growth and ultimately
reduces dissolved oxygen levels in the water. Raw Sew-
age is the source of nitrogen and phosphate in rivers
[11,12]. [9] observes that land use around riverine areas
in Nigeria is predominantly for farmland and this could
be explanation for the high level of phosphate from run-
off during rainy season in Ibadan River. As a conse-
quence of unprecedented development human beings are
*Corresponding a uthor.
C
opyright © 2013 SciRes. JWARP

N. O. ERHUNMWUNSE ET AL. 744
responsible for choking several lakes to death [9].
Rivers in Nigeria are important ecosystem as they
serve as a main nutrient source for aquatic organisms,
source of water to neighbouring communities for domes-
tic and industrial purposes. Therefore the water quality is
important in drinking water supply, irrigation, fish pro-
duction, recreation and other purposes. Current practices
of Nigeria living in the southern part of the country ob-
served by concerned environment are regular dumping of
dirt and waste material in large quantities into water
bodies and flood which even tually carry them into rivers.
Water quality deterioration in water bodies in the
country resulting from excessive nutrient inputs (Eutro-
phication) needs to be checked as a result of the effect of
such phenomenon on the social economic function asso-
ciated with water bodies.
2. Causes of Eutrophication in Nigeria
Gromec [13] states that the causes of eutrophication are
related to meteorological and climatic status anthropo-
genic activities. The aq uatic environment, where fish and
other aquatic organisms live, is subjected to different
types of pollutants which enter water bodies through in-
dustrial, domestic and agricultural discharge systems
thereby introducing stress to living creatures. The dis-
charge of industrial effluents into receiving water bodies
in Nigeria invariably results in the presence of high con-
centrations of pollutant in the water and sediment [14].
The constant flow of agricultural effluent discharge into
water bodies often leads to a variety of pollutant accu-
mulation, which becomes apparent when considering to-
xic pollution [15].
Nwaze et al. [16] indicated that indiscriminate use of
fertilizers around Nike lake in Enugu, Nigeria is the ma-
jor source of pollution causing Cyanophycean blooms
and ecological disaster. Stirin [17] pointed out that the
time frame for natural eutrophication to occur is about
1000 - 10,000 years as against cultural eutrophication of
less than 10 years caused by human activities. Since the
population boom in Nigeria in the 80’s the use of N.P.K
fertilizer has increased and led to the treat observed in
water bodies located close to these farmland. When
washed as a result of erosion, flooding increased the nu-
trient load of these water bodies. Other anthropogenic
activities that can cause eutrophication in water bodies
include increased silt, deforestation, lumbering activities
and other land use perturbation.
Ekhaise and Anyansi [18], reported high counts of
bacterial population in Ikpoba River in Benin City Nige-
ria receive brewery industrial effluent. Similar results
were reported by [14] of the effect of brewery discharge
into Eziama River, Aba, Nigeria. Val AL, Paula da.,
Silva MN and Almeida-Val V MF [1], pointed out re-
gardless of the origin of eutrophication, its end result
usually led to change within the aquatic communities.
3. Effect of Eutrophication
Lundberg, [19] stated that eutrophication will cause hy-
poxia and anoxia in aquatic life as a result of sedimenta-
tion associated with primary production. Eutrophication
is related to physical, chemical and biological distur-
bances, increased production of algae biomass, the de-
creasing amount of silica and increased turbidity of the
water bodies [14], foul smell and will eventually lead to
the death of the water bodies. Nitrogen and phosphorus
are the major causes of eutrophication. Eutrophication
affects aesthetics on lak es, rivers an d results in odour and
appearance problems [15]. It reduces the anesthetic qual-
ity of water for recreational activities, like swimming,
boating, and picnic.
The presence of high algal biomass occurring from eu-
trophication of the shallow tropical African reservoirs
will jeopardize the effective functions of the reservoir in
providing domestic and industrial wa ter supply, fish pro-
duction, irrigation, recreation as well as loss of biodiver-
sity and other socio-economic functions of the reservoir
[20]. Loss of biodiversity and socio-economic functions
of the reservoir, poor water quality, anoxia, low trans-
parency and disruption in food web interactions is some
of the effects of cultural eutrophication in these lakes.
3.1. Managing Nutrient and Water Quality
Although in Nigeria, the Federal Ministry of Environ-
mental is saddled with the responsibility of providing
guide line for managing effluent discharge into the envi-
ronment. This body provides the frame work for every
industry involved in the utilization of water resources
and hence ensures the protection of water bodies across
the country. The main objective is to ensure all those
involved in discharging effluent into water meet the re-
quirement in order to protect water use.
It is therefore of paramount interest for FMENV
(NESERA) to work with the River Basin Authorities in
order to combine effort in controlling pollution and the
self guideline to be followed strictly. Following the water
quality standard set by [21] (NESERA) it is of interest
that company’s effluent must be checked regularly to see
if they conform to the existing standard and to check the
effect of population growth on their production which in
turn, increases the waste discharge into the environment.
Nutrient management is important to assess the impact of
human activities from known sources (Point Sources)
and from diffuse sources and other human activities [13].
The established water quality Criteria by [21] after the
illegal dumping of toxins in Koko Port in the then Bendel
State: Nitrate (No3) 20 mg/l for surface water, Phospho-
rus (3
4
Po

) 5 mg/l for surface water and 10 mg/l for land

N. O. ERHUNMWUNSE ET AL. 745
use. The standards were adopted for monitoring water
quality based on the method for water and waste water
analysis by United States Environmental Protection
Agency (USEPA) Department of Environment (DOE)
UK, American Public Health Association (APHA).
If the above criteria and requirement must be meant,
the state of the art equipment must be acquired by the
industries involved. Effluent must be properly treated to
meet these standards as point source of population.
Controlling non-point source has always been difficult
as the cause and effect cannot be directly documented. In
recent past, non point sources of nutrient from agricul-
tural practices have been analyzed with the aid of mathe-
matical models, based on the presentation of reliable and
correct data. In Poland, such model has been developed
and can be used in the Nigeria context [22]. In line with
the above statement, the total nitrogen and phosphorus
were calculated using data collected from point source
and subtracting it from the total, the applied mathemati-
cal model method an agricultural field model which de-
scribed the over-all nutrient runoff from the root zone
and agriculture practice. Again a catchments model is
suitable for describing the overall transport of water and
nutrients through the river basin including different nu-
trient and concentration in different water compartment
and lastly a full hydrodynamic and water quality model
system as developed for rivers, lakes and wetland areas,
describs water flow, transport and transformation of or-
ganic material and nutrient.
3.2. Mathematical Model for Measuring
Pollution/Pollution Index
Value of Nitrogen/Phosphorus of a water body from
non-point source = Mean Total value (MT) of Nitro-
gen/Phosphorus of the water body-Value of Nitrogen/
Phosphorus from point sour ce of the same water body.
3.3. Recommendation
A comprehensive systematic survey of the eutrophication
status of Nigerian waters should be undertaken and na-
tional framework for managing eutrophication should be
defined with the key elements of which are:
 A two-pronged appro ach whereby measures to reduce
nutrient inputs to the water environment nationally are
complemented by more comprehensive, catchment-based
management action, within the context of a national
framework, for waters most at risk from or affected by
eutrophication;
 The promotion of a partnership approach, at both lo-
cal and national level, since solutions are generally be-
yond the re mit of any one regulatory body or other party;
 The adoption of a range of mechanisms (regulatory,
voluntary, collaborative, educational and economic) by
the Agency and others, as appropriate, in order to reduce
nutrient inputs to environmental waters and manage local
problems;
 The development and adoption of consistent method-
ologies for assessing eutrophication in a water body;
 A review of the arrangements for measuring the ex-
tent of eutrophication in the different types of environ-
mental waters and the impacts of discharges and land use
on water quality;
 The prioritization of waters for management action:
initial priorities will be waters where there are statutory
requirements, or where water uses are adversely affected,
or where wildlife conservation interest is at risk, where
benefits can be delivered or deterioration prevented, with
adequate confidence, at reasonable cost;
 The adoption of interim targets for eutrophication
control in freshwaters and the continuing application of
specific statutory and/or international commitments in
relation to saline wat ers by reg ulatory bodies;
 Trials of the proposed tools, techniques and proce-
dures through pilot catchment-based action plans, to re-
fine the approach and its potential wider adoption within
the country;
 The promotion of a wider understanding of the nature
and significance of aqu atic eutrophication;
 A programme of research and development to im-
prove understanding of the eutrophication process within
Nigeria should be set up.
4. Conclusion
For the effective management of Nutrient load of water
bodies in Nigeria, both point and non-point sources of
pollution must be taken into recognition and controlled.
Strict compliance to the combined guidelines by NESE-
RE and River Basin Authority must be met without
compromises. The Federal Government and the Ministry
of Environment must set huge amount from the ecologi-
cal funds for proper evaluating by hydrobiologist and
toxicologist in the nation. Land use coupled with other
anthropogenic activities near this water must be moni-
tored and in some cases relocated always from these wa-
ter bodies. The threat of water pollution to man’s exis-
tence has informed the adaptation strategies aimed at its
control and one of such strategies according to Imhoff
[23] is the provision of information on the quality and
quantities of contaminant in a water body.
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