Integrated Water Management for Lake Toba

Lake Toba is the biggest resource of fresh water in whole South East Asia. This needs to be protected and can not be used or destroyed by:

  • Companies they go for deforestation and reduce the rainfall around Lake Toba like Toba Pulp Industries (TPL) and other often illegal logging
  • by burning all the hills around Lake Toba all the time
  • destroy the water Quality of the entire lake by illegal (international and national law) fish farms, they give the excrement of the fish to the lake. Alone the Fish farms Regal Springs has an impact, like 1,2 million people shit directly to the lake.
  • Just use the water to produce electrical energy to get the level of Lake Toba down under a minimum, that the fish loose their space for breading.
  • Making drains all around Lake Toba, that the erosion is getting much bigger and all the water getting unfiltered by the land directly to the lake.

There are much better alternatives in an Ecologic and economic way to go around with this problem.


All the still existing forest has to be protected in the moment as a national park, that the deforestation cannot go on. If it is already clear, that the deforestation around Lake Toba is the problem, that less rain fall, than this is first step of a government to stop the ongoing process of a Deforestation as the first step.

The second step then can be, how to get more intense vegetation around Lake Toba again. This needs a training of the farmers, that they don´t go anymore to open the earth and work with roundup and give plastic on the earth. All of this reduce the rainfall. It needs:

  • a agriculture which is working in several levels. Just for an example:
    • on the ground can grow Chili, it like shadow and protect from a lot of insects and diseases
    • the next floor coffee, the main product, which like to grow together with chili
    • above Banana, after harvesting it is the best compost
    • and then a huge Ingul tree, it grow fast up and all the other things can grow down under and it is later a perfect wood. Also the juice and the bark is a natural antibiotic.
  • with this all the earth is covered
  • with the different floors the plants can absorb nearly all of the sunlight and it is not getting reflected. It gives to the coffee much more humidity, even in a dry season. The earth cannot dry out
  • all the minerals and nutrition is not swamped away by a heavy rain.
  • it protects from erosion which carry away the soil.
  • It will attract the rain in a natural way

Reduce the nutrition intake to the lake

There are a lot of facors which give a nutrition intake to the lake. Especially phosphates are a huge problem. The main producers are and how it can be solved:

The Aquafarms

The Aquafarms which their flaoting nets produce around 70 % of the intake of nutrition to the lake. By the Sustainable Development Goals (SDG)’s, which are signed by Indonesia all kind of this Business is not allowed by the United Nations anymore: “OPEN WATERS CANNOT BE POLLUTED”. This has to be also Indonesian law and also it is an Indonesian law. The prosecution, the Government,  the Environment offices, the police has to work on it and has to look, that there is NO intake to the lake out of this Business anymore.

Even more, the Government has to accuse the producers since the 1. January 2020 to pay for the destruction, they give to the lake. For each Kilo of Nutrition they give to the lake, they have to pay the amount, to repair it.

The Aquafarms can produce on the land with the System of Aquaponic also Tilappia in a very good Quality. This will be even cheaper, then the expensive open nets, which all the time need maintenace and with each strom a lot of fish they loose. With Aquaponic systems the excrements can be used as a fertilizer to grow Soya Beans or Azoll Algae, which have also 13 % Protein and clean the water for the fish again.

The existing floating nets can be modified to floating hotels. This will be a unique thing and will find worldwide a lot of Customers, they will enjoy to sleep on the lake. This can be 5 star Eco resorts for western people, they want to be away from everything.


All the new draining all around Lake Toba and all Indonesia is totally sub optimal. everywhere, you make the rainwater collecting and going more fast, you will have a lot of Erosion and a lot of soil and a lot of nutrition is being transported directly to the lake.

  • For example Drains in Tuktuk and Tomok
    Before there have been a drain, what happen with the water from the houses? The houses have had a “septic tank” which made the first step of a water cleaning. Then the water was going to the soil and was getting filtered by the soil, before it went to the lake.
    Now the water go from the houses without filtering directly to the Lake. That means all the washing detergent, which was before a fertilizer for the plants around the houses are now a nutrition intake to the lake.
    Much better would be to teach the people make a pond in front of the house, where the water after the septic tank go, and produce there on the top Azzolla and catfish. What leave then the pond should go spread to the soil around. With this all the houses would have a 3 step water cleaning system and an additionally income or own production of nutrition.
  • Draining of the Roads
    The drains of the roads collect in a rainfall all the water around. All the for example fresh given fertilizers from the agriculture around are getting swamped in the drain and getting directly transported to the lake.
    For a road it is important, that the water is not running fast on the road or even down under of the road. The speed  and the amount of the water on or at the road has to be reduced, that a road is not getting broken very fast. But to make a drain 2 meters away from a road, that the water direktly find the way between the road and the drain is more then sub optimal. This you can see so often and a road is getting broken even a half year after it was built new.
    A drain alone is not a solution and only cause other problems. At the most

    A description by the Government of Bavaria, how a road has to be built in the forest

    places, it don´t need a drain. It needs, just that the water can go directly down from a road. for this it is enough, that the road is high in the middle and water can flow directly to the side. There is just earth, where the water can go to the ground and don’t make a river.

    When it is going steep down then the water is getting close by collected in an area, where it can make a temporally pond and the water is going later to the ground. It is important to seal as less of possible of the earth, that the water can go to the ground. Therefore at the side of the road it is good when it is just filled with small stones and sand, which easy can take the water.

    But if the water is going down with a drain directly to the lake, then all the pollution of the road (Oil, resiuals from the brakes) and transport also all the fertilizers from the field without any water treatment to the lake, then this is getting even a more worse pollution of the lake. Also this is forbidden by the Sustainable development Goals of the United Nations.

    And with this also the drain produce more erosion, what you can directly see at the roads on the hills on Samosir.

Usage of the Water for Production of Electric Energy by Inalum

To produce electricity with water energy is a way of a sustainble energy production. Also the water, which fall down from a level of 900 m sea level and the huge amount of water what need to go down from Lake Toba this is a very good thing – for the first.

But in sustainable energy mix, then the water from a huge lake like Lake Toba it is for sustainable energy production a perfect source for peak level production, when the other energy like sun and wind are not working. For this the water of Lake Toba should be used.

To generate a sustainable Energy System the source of wind and sun has to be used. The installment of Wind Turbines on the mountains around Lake Toba costs if you go for the world average price of 1457 USD/KWh, than it needs an Investment of around 800 Million USD. But the production cost of 1 MWh is 29 USD. (Source Wikipedia) Therefore wind energy is the cheapest. It make sense to make this Investment. Then Inalum can sell the energy when the electric system needs more power for peaks. Then this energy can getting sold much more expensive. This is a normal market mechanism. With this the water of Lake Toba has much more worth.

But to go with Aircrafts to spray salt in the sky to attract rain to lake Toba to produce electric energy seemed to be a very funny experiment. If you read the article in DETIC-News ,that they want to start with this at the 1. April 2021, than you normally can think, this is just a April joke. But it seemed to be true. But the effect is the same, you have to laugh about this.

How much it costs to produce with this action 1 MWh? Quite sure, 10 to hundred times more, than to invest in Wind energy.

And what happens, if the rain then fall down with this action on Lake Toba?

  • it cannot fall down later naturally from the sky, because already it fall down.
  • The concentration of water in the sky is getting less with this, that the next day it cannot rain naturally
  • Lake Toba still has much more rain, then the area around because of the hills the water is condensing naturally, but with this action, the water is taken down to Lake Toba and in a dry season it cannot down somewhrer else in the region, where the rain is very importannt, that not all the fields dry out.
  • You take the water to Lake Toba to produce Energy, but the rest of the surrounding can suffer and not even produce food anymore.
  • With the aircrafts you produce a lot of CO 2 which increase the climate change.

Sorry but this action it difficult to take it serious.

Maybe it make sense, if you make this in a dry period on a small island, before all the plants dry out, to safe an harvest.