1

A Concerted Effort to Save Tana

GLOBAL COALITION FOR LAKE TANA RESTORATION

Prepared by:

Dr. Solomon Kibret Chair, Global Coalition for Lake Tana Restoration University of California, Irvine United States

November 2017

2

Acknowledgement

This project was partly financially supported by Gojjam Global Alliance of Canada and Gojjam

Global Alliance US. A number of people and institutions participated in this work. Drs. Abeyou

Wale and Yihun Dile, members of the Scientific Committee of the Global Collision for Lake Tana

Restoration, analyzed satellite images. Members of the Geospatial Center of Bahirdar

University, namely Zinabu Getahun, Minyichil Alemu and Meleket Yibabie, helped in the data

collection in the field. Members of the Amhara Regional Environmental Bureau such as Dr

Belayneh Ayele, Mezgebu Asres, and Negash Atinafu participated in drafting the strategic

roadmap.

3

Background

Lake Tana is the largest lake in Ethiopia, accounting 50% of the country’s freshwater resources.

It is approximately 84 km long and 66 km wide, with a maximum depth of 14 m and a surface

elevation of 1,788 m above sea level. Its surface area ranges from 3,000 to 3,500 km²

depending on season. The lake is fed by several rivers, with 97% of the water coming from four

major rivers: Gilgel Abay, Ribb, Gumara and Megech. The annual inflow to the lake is estimated

to be 4,986 Mm3 per year. The plains surrounding the lake (i.e. the Dembiya, Fogera and Kunzila

plains in the north, east and southwest, respectively) form extensive wetlands favorable for

large- and small-scale agriculture. As a result of the high heterogeneity in habitats, the lake and

surrounding riparian areas support high biodiversity and are listed in the top 250 lake regions of

global importance for biodiversity.

Lake Tana hosts 65 fish species – a quarter of which are endemic to the lake. Among them, it is

home for eighteen species of barbus fish (i.e. of the Cyprinidae family) and the only extended

cyprinid species flock in Africa. Other common fish species include tilapia (Oreochronmis

niloticus) and catfish (Clarias gariepinus). A study in 1996 identified 217 bird species around the

lake, with a minimum of 20, 000 water birds. The lake shore is also characterized by its

extensive papyrus (Cyprus papyrus). Over 4 million people are estimated to live in the lake

catchment and at least 15 000 people are believed to live on the 37 islands in the lake

The lake has tremendous socioeconomic benefits to the country. The major economic benefits

include irrigation, hydropower generation, tourism and fishery. Several monasteries located in

the lake’s islands have historical and religious assets. Studies show that the lake basin has an

irrigation potential of 517,500 hectares of land. The potential fish production of Lake Tana is

estimated to be 13 000 tons per annum. However, its current production is only about 1000

tons per year. Recent studies indicated a serious decline in fish stocks due to the spread of

water hyacinth around fish spawning grounds.

4

Current threats of Lake Tana

Water hyacinth, Eichhornia crassipes Martius (Pontederiaceae) is an exotic free-floating

perennial plant that is native to South America. It is one of the fastest growing plants known.

Water hyacinth is considered as an invasive species. If not controlled, it will rapidly and

thoroughly cover entire surfaces of lakes and ponds – dramatically impacting water flow,

blocking sunlight to native submerged plants, and depleting the oxygen in the water - often

choking aquatic animals such as fish. Major economic impacts caused by invasion of water

hyacinth include interference with navigation, irrigation and power generation, and fishery.

Water hyacinth is an aggressive invader and can form thick mats. Dense mats of this plant can

also provide ideal mosquito breeding habitats. It is very important to control water hyacinth

before the entire water surface is covered. Recent data have clearly showed that Lake Tana is

critically infested with this weed and the aquatic biodiversity of the lake is extremely at risk.

In 2011, water hyacinth was officially recognized as one of the top ten ecologically dangerous

and worst invasive weeds infesting Lake Tana. Unpublished literature indicated that about

20,000 hectares of the north-eastern shore of the lake was estimated to be infested with water

hyacinth. Likewise, a team of researchers from Bahir Dar University reported that about one-

third of the shoreline (128 km length) of the lake was invaded by water hyacinth in 2014.

According to gray the literature, the estimated coverage of the weed doubled in just two years.

As a consequence, the lake has lost 75% of its fish production in recent years. This clearly shows

the pressing threats of the weed on the lake’s environment and aquatic life.

Currently Lake Tana has faced serious ecological threats that affected its aquatic biodiversity.

Pollution, sedimentation and water hyacinth infestation are the major threats to the lake. In

October 2017, Global Coalition sent technical personnel to the area to study the current status

of water hyacinth and identify control measures to eliminate the weed and restore a healthy

ecosystem. A five-year strategic roadmap was also drafted together with the Regional

Environmental Bureau.

5

Findings from the Global Collation for Lake Tana

A team of researchers from the Global Coalition for Lake Tana Restoration (a US-registered not-

for-profit initiative) and Geospatial Center of Bahirdar University spent a number of days in

September-October 2017 around Lake Tana assessing the extent of water hyacinth coverage

and assessing economic and ecological impacts of the weed on the environment. Using hand-

held GPS, the distribution of water hyacinth was determined. The results of the study indicated

that a total of 5,037 hectares of the shoreline were infested by water hyacinth as of October

2017. The infested area covers the northern, northeastern and eastern shores of the Lake that

stretches 140 km (Fig 1).

Fig 1. Current distribution of water hyacinth in the northern, northeastern and eastern

shorelines of Lake Tana, October 2017.

6

A total of 20 kebeles have been infested with water hyacinth in the northern, northeastern and

eastern parts of Lake Tana (Table 1). These parts of the lake are known for agriculture and

fishery. A number of rivers enter the Lake Tana in these sections of the lake. Consequently,

large loads of sediment and dissolved nutrient washed away from upstream Tana catchment

enter the lake through these rivers. Due to the presence of high dissolved nutrient such as

nitrogen and phosphorus, river mouths have become favorable habitats for water hyacinths.

The irony is that river mouths are important breeding grounds for fish, where the weed will

impede its very existence. The presence of massive mats of water hyacinths will block sunlight

and oxygen to the aquatic habitat which will significantly affect the fish population. A recent

study indicated that the fish population in the Lake Tana basin decreased by up to 75% in the

recent years. Perhaps, the emergency of the weed contributed to this remarkable fish stock

decline.

Table 1. Coverage of water hyacinth by kebele around Lake Tana, Oct 2017.

No Zone Woreda Kebele Weed coverage in ha

Status*

1

South Gondar

Dera Mitsili 260 High Fogera Wagetera 155 Intermediate

Nabega 326 High

Libo Kemkem

Tezamba 540 High

Kab 348 High Agid 132 Intermediate Kirigna 18 Low

2 North Gondar

Gondar Zuria Mitriha Aba Warka 195 Intermediate Firka Dangure 133.5 Intermediate Sheha Gomene 33.5 Low Lemba 398 High

East Dembia

Jarjar 339 High

Tana Woina 903 High

Adisge Dinge 187 Intermediate

Achera 756 High

Seraba Dablo 591 High West Dembia

Dahna Wawa 18 Low

Gorgora 13.2 Low

Abrjeha 14.6 Low

Mange 15.2 Low Grand total 5,037 * Status is defined as follows: >200 ha High; 100-200 ha intermediate; <100 ha low

7

Moreover, studies show that water bodies covered with water hyacinth are subjected to about

eight times higher water loss than an open water. This resulted in more evaporation in the

wetland where the weed exists. Perhaps, the drying of the wetlands of Dera and Fogera

woredas may be related to the presence of this weed. Our findings have indicated that tens of

thousands of households have lost their livelihood because of the invasion of water hyacinth.

Unless appropriate measure is taken the impact will get worse on the local livelihood, national

economy and aquatic ecosystem around Lake Tana.

Among the 20 kebeles that are infested by water hyacinths, just four of them (Tana Woina,

Achera, Seramba and Tezamba) accounted for 55% of the total weed coverage around the lake

(Table 2). Generally, nine kebeles are considered as highly infested (>200 ha/kebele) and five

kebeles are infested at intermediate level (100-200 ha/kebele) whereas six kebeles are infested

at low level (<100 ha/kebele) (Fig 2). Satellite images indicated that the weed were expanding

at a rate of 13 ha per day during the rainy season (June- September) (Fig 3), mainly due to poor

planning and management of manual campaigns. During these campaigns, people were not

trained about weed removal procedures and designated sites were not arranged for disposal of

the harvested weed. Most of the harvested weeds were left at the edge of the shoreline

subjected to be washed away by rain – which then dispersed the weed to a wide area as the

weed also propagates vegitatively through its detached stolon.

Fig 2. Relative density of water hyacinth across Lake Tana, Oct 2017

8

Our study revealed the tremendous impact of water hyacinth on the functions of the Lake and a

well-designed weed management approach is required to stop the weed from covering the

entire lake. Satellite images showed that water hyacinth infested areas are very shallow and

this understanding is important in selecting appropriate water harvesting machines based on

local context. Based on the findings of this study, experts from the Regional Environment

Bureau, Global Coalition and Bahirdar University drafted a five-year action plans that need to

be done in order to eliminate the weed and restore a healthy ecosystem.

Fig 3. Periodic increase of the water hyacinth mat around Lake Tana, based on high

resolution satellite images (Note the difference in coverage between satellite data) (Wale et

al, GCLR Scientific team)

Fig 4. Water depth of areas infested with water hyacinth generated from satellite images

(note shallow areas of the lake are currently affected by the weed) (Wale et al, GCLR

Scientific team)

9

What need to be done?

The Amhara National Regional State Regional Environmental Bureau in collaboration with

Global Coalition and Bahirdar University has drafted a five-year strategic document that maps a

detailed plan of actions needed to eliminate the weed and rehabilitate the degraded

environment of the lake’s catchment. The strategies identified short-term and long-term action

plans. A total of 3 million USD is required to implement all activities planned for the next five

years.

Short-term plan

The short-term plan aims creating a strong capacity at regional and local level and implement

water hyacinth elimination activities across Lake Tana within the next one to one-and-half

years. The cost for short-term activities is USD 700,000.

a) Capacity building: In the short-term, a special Unit called “Water hyacinth control and

management Unit” will be structured at the Regional Environmental Bureau. This Unit

will lead and coordinate all activities around Lake Tana. This Unit will support and work

closely with local NGOs and other stakeholders to achieve the anticipated goals of the

strategic document. Highly trained professionals (including experts of aquatic plant,

environment, GIS and M&E) will be hired. The Unit will also have kebele coordinators in

each of the 20 infested kebeles. Kebele coordinators will be trained locally and ensure

the implementation of action plans at local scale. In addition, international trainers with

a great deal of experience in water hyacinth control in Africa and elsewhere in the world

will be engaged to train experts at governmental and non-governmental agencies who

are working to address Lake Tana’s challenges.

b) Water harvesting machines: three water hyacinth harvesting machines are needed to

work in northern, northeastern and eastern parts of the lake. Daily operational,

maintenance and manpower costs are calculated. Conveying belts that extend from the

water body to the dry land are also required to unload the harvested water hyacinth

10

from the machines and transport it to the shoreline. Carts and trucks will then transport

the harvested weed from the shoreline to the designated disposal area (large pits)

prepared away from the water body. The weed currently existing in twelve highly

infested kebeles (of the total 18) will be removed using these machines.

c) Manual removal: For health and practicality reasons, manual weed removal are

confined to only a few kebeles which are with low risk of schistosomiasis and practically

possible.

d) Grass plantations: Local studies indicated that endegenous grass species help avoid

water hyacinth expansion due to their ability to absorb excessive nutrients from the

water. In areas where water hyacinth is removed, such grasses will be planted and

maintained in order to create conditions unfavorable for the weed.

e) Waste water management system: A well-studied waste water management system

will be implemented around Lake Tana in order to reduce dangerous waste water

influent into the lake catchment.

f) Operational researches: Areas of knowledge gap will be identified by the Scientific

Committee and researches will be conducted to understand the mechanism of water

hyacinth propagation and distribution. Environmental variables that contribute to

favorable conditions for water hyacinth development will also need to be assessed well.

The effect of control measures will also be periodically assessed and approaches will be

revised accordingly. Biological control measures are still in “study” phase and this needs

to continue until we understand their impact on the environment.

Long-term

i) Environmental rehabilitation: The environment of Lake Tana has deteriorated due to

high rates of deforestation and increased agricultural practices. Afforestation programs

are needed to restore the forests of the catchment. Planting endegenous plants and

protecting deforestation is critical to rehabilitate the degraded environment and reduce

soil and nutrient erosions upstream of the lake.

11

ii) Ecosystem payment: Regulations will be drafted to charge ecosystem payments from

beneficiaries operating businesses around Lake Tana. This helps to generate income for

environmental management activities. Such incomes help reinforce wastewater and

environmental management activities around the lake’s catchment. Businesses will be

trained to be environmentally friendly.

iii) Improving fish productions: New policies and regulations are needed to protect illegal

fishery and maintain a healthy fish habitats. Periodical trainings and discussions will be

conducted with the fishery community to help them contribute in maintaining a healthy

aquatic environment.

iv) Improving agricultural practices and livestock management: Improved agricultural

practices are required to reduce soil erosions. New technologies and agricultural

practices that fit the area traditional and cultural assets will be implemented and such

practices will help manage the environment better. Improved livestock management

will be practiced to avoid overgrazing which facilitates soil erosion.

Monitoring and evaluation

Monthly, quarterly and annual field and satellite data will be collected and analyzed by an M&E

Team composed of experts from the Global Coalition, Bahirdar University and international

universities. Time-series satellite images will be analyzed to monitor the status of water

hyacinth and environmental factors around Lake Tana. These reports will be discussed with the

Regional and Federal Environment Bureaus in Ethiopia. In addition, the reports will be publicly

available on the Global Coalition website for anyone interested to follow-up the work. Global

Coalition will host symposiums annually to discuss M&E findings with Chapters formed in each

state and country across US, Canada, Europe and Australia. The Board of Trustees of the Global

Coalition will oversee overall activities of the Coalition and partners working to address the

current challenges of Lake Tana. The Coalition aims to be open, transparent and participatory in

decision-making and directions it takes while managing and providing technical, material and

financial supports to the work done around Lake Tana.

12

Picture: Water hyacinth mat in Achera, Dembia Woreda, Ethiopia (Oct 25, 2017)