What we do

We live in one of the most dangerous areas in the world because our country lies below sea level. To protect ourselves from the water, we have built dikes and quays. Sometimes there is a lot of rain in a short period of time. We store the excess water in areas designed for that purpose. That way, we keep our feet dry. We have to learn to live safely with sometimes too much and sometimes too little water. 

We do a lot of work to live safely with water. This will also be the case in 2024:

Reinforcing Lauwersmeer dike

The Lauwersmeer dike in Groningen is located between Lauwersoog and the Westpolder. We are currently reinforcing this dike to protect ourselves against flooding from the sea in the future. After a period of preparation and joint planning, we started work in 2023. The dike reinforcement will continue until 2027.

We made great strides in 2024. We reinforced 4,500 meters of the national dike and installed new sheet piling on the harbor dike. We also constructed a brand-new 450-meter bicycle path and a 250-meter walking boulevard. This year, we used around 45,000 m³ of sand, 34,000 m³ of clay, and more than 21,000 tons of rubble for the dike reinforcement, and we sowed more than 100,000 m² of grass. Our electric work vehicles ran for a total of around 10,000 hours and consumed approximately 300,000 kWh of green energy. The dike information center was also busy: we welcomed almost 2,000 visitors this year, 500 of whom came during Construction Day. In short, it was a successful year!
 

Would you like to know more about the dike reinforcement? There is a special website with all the information about the dike reinforcement: Dike reinforcement Lauwersmeerdijk-Vierhuizergat.

Storm and high water

In 2024, we experienced several instances of high water and storms. The period between October and April is referred to as storm season. During this time, we are ready to monitor the dikes and quays.

Between the city and the port of Delfzijl lies a 750-meter dike. It protects the city from seawater. There are four passages in the dike. This allows us to go from the city to the port and vice versa. These passages have large doors: two electric roller doors, one revolving door, and one sliding door. We close these doors (also known as 'coupures') when the water level exceeds 3 meters above Amsterdam Ordnance Datum.
 

Every year, we practice closing the floodgates: Exercise closing the Delfzijl dike passages this year on September 25. And at the end of December, we closed the dike passages in Delfzijl due to high water: Delfzijl dike passages closing tonight due to high water at sea.

During the exercise, we made the video below:

Muskrat management

No more muskrats in our area by 2034. That is our goal, and our colleagues are working hard to achieve it. We are combating muskrats because they damage flood defenses and riverbanks by digging burrows and tunnels in dikes. They also build nesting chambers with extensive underground tunnel systems. They can cause subsidence in dikes and quays, and we want to prevent that.

Muskrats and coypu also pose a threat to biodiversity. Both animals are therefore on the European list of invasive species. They eat plants such as reeds and cattails, thereby displacing native species such as the black tern, the bittern, and the reed warbler. These birds live in the reeds, which is also the habitat of muskrats and coypu.

An overview of the muskrats and coypu caught in the North can be found below:
 

We caught three coypu in 2024.

We have muskrats and coypu under control in our area. This also explains why the catch numbers are lower compared to other water boards. 

Water mountains

When there is heavy rainfall, the water level in waterways rises and the soil becomes saturated. This can cause nuisance. Sometimes unsafe situations arise. During wet periods, the water board works to manage the situation in order to reduce nuisance and prevent unsafe situations. This animation shows how we do that.

As shown in the animation above, we are preparing for extreme situations involving very large amounts of water. When we are unable to drain the water sufficiently and water safety is at risk, we deploy so-called water storage facilities. These are parking lots where we can temporarily store the excess water. In 2024, we worked on preparing and realizing new water storage facilities in our area. We are doing this in De Onlanden and in the Zuidelijk Westerkwartier. 

• You can read more about De Onlanden and what we have done on the page about De Onlanden: Expansion of water storage at De Onlanden.
• More information is also available about the Dwarsdiep. This information can be found on the website for area development in the Zuidelijk Westerkwartier.Zuidelijk Westerkwartier.

Clean and healthy water is an important core task within the water board. Healthy and clean water is important for us as humans, but also for plants and aquatic animals. We work with many organizations to make surface water increasingly cleaner. We do this, for example, by using fewer pesticides, creating more nature-friendly banks, redesigning certain waters, dredging, combating exotic species, and more. 

Paterswoldsemeer

In recent years, the Noorderzijlvest Water Authority has taken various measures to improve water quality. The goal: clean water, a wide variety of plants and animals, little blue-green algae, and manageable aquatic plant growth. The drainage route to Hoendiep has also been addressed.

By 2024, nature-friendly banks and zones, fish hotels, and fish forests will have been created in various locations. These areas offer fish and small aquatic animals a safe haven in which to develop. They strengthen the ecological balance and thus the water quality. Step by step, nature is returning. In places where aquatic plants cause nuisance to recreational users, the Meerschap mows them according to the aquatic plant management plan. In this way, the plants contribute to the ecology of the lake, while recreational users can continue to enjoy the water.

It is a combination of measures that will ultimately improve water quality. In an earlier phase, a fixed water level and a new weir with a fish passage were already installed. An iron sand passage was also constructed. The iron sand filters phosphates from the water, keeping the lake cleaner and reducing the risk of blue-green algae.  

Want to read more about this project? You can do so for a few more weeks on the Paterswoldsemeer project website: Home | Paterswoldsemeer Area Program

Lauwersmeer area

We are also working to improve water quality around the Lauwersmeer area. We are doing this in collaboration with many other parties. An important focus of the work in the Lauwersmeer area is to offer prospects for both nature and agriculture.
In this unique area, work is being done to restore a more natural transition between fresh and salt water without disrupting agriculture. 

At present, the R.J. Cleveringsluizen locks and the dike form a relatively harsh transition between fresh and salt water. This is unfavorable for fish and therefore for the natural quality of the Wadden Sea and Lauwersmeer. The availability of fresh water is important for agriculture. In order to take both into account, the first step is to establish a more comprehensive and accessible system for measuring salinity in and around the lake.

In 2024, we worked hard to prepare for the construction of a so-called Salt Water Monitoring Network in the area. The chloride monitoring network will be set up in 2025 and 2026. Measuring points will be installed in the lake and in nature and agricultural areas. This will allow the salinity to be measured daily at different locations and depths. We are also developing an online dashboard.  

Swimming water and PFAS

From May 1 to October 1, we monitor the water quality of the swimming lakes in our working area. The water board manages 17 official swimming locations. The video below clearly shows how we do this:
 

We also checked our swimming locations for PFAS in 2024. The PFAS content in swimming waters in the province of Groningen is low. This is evident from checks that we recently carried out together with the Hunze en Aa's and Wetterskip Fryslân water boards. This means that enthusiasts can continue to swim safely in the designated swimming lakes. 

The results show that the PFAS concentration for all swimming locations investigated is well below the RIVM guidelines. According to these guidelines, a maximum of 280 nanograms of PEQ (collective name for several types of PFAS) per liter is allowed in swimming water. The values found in Groningen ranged between 0 and 37 nanograms. This means there are no health risks for swimmers.

We all use water. The water board cleans this water. This amounts to 55 billion liters of water per year. The Noorderzijlvest water board has thirteen treatment plants. We have 401 kilometers of pipes and 110 pumps to transport the water from homes and businesses to the treatment plants. We purify this water in a natural way at the treatment plants. Once the water is clean, we discharge it back into surface water, for example into the Eemskanaal or the Van Starkenborghkanaal.

Modernization of the Garmerwolde wastewater treatment plant

Better purified water is a significant step closer at our sewage treatment plant (STP) in Garmerwolde. The first of three treatment lines has been modernized and renovated in recent months.

The 'line' was officially put into operation in November 2024. There are already positive reports about the performance of the renovated line. The removal of nitrogen from the water used by households and businesses is improving. In addition, the use of chemicals in the purification process is decreasing significantly.

We are proud of these initial results. We are now focusing on tackling the other two treatment lines in the coming years.

Over the past few months, we have been working hard with our partners at the Garmerwolde wastewater treatment plant (WWTP) to renovate, renew, and optimize one of the three treatment lines!

The goal: to treat sewage in a more user-friendly and sustainable way. We are reducing nitrogen emissions and adding fewer chemicals during the treatment process. 

What have we done?

• ✔ I. Intermediate settling tank
  The intermediate settling tank has been cleaned and inspected. We are increasing employee safety by installing a raised railing.
• ✔ II. Aeration tank
  In the renovated aeration tank, the water follows a longer, zigzagging route. More aeration plates have also been installed. This gives bacteria more time to remove nitrogen from the water. The mechanical and electrical components in this system have been renovated and partially replaced.
• ✔ III. Settling tanks
  In two settling tanks (each with a capacity of 4000 m³), the circulation channels, inlet drums, and cones have been replaced. In the settling tanks, the purified water is separated from the sludge. The purified water is then discharged into the surface water. The sludge is also further treated, including fermentation and compression into sludge cake.

New construction of public kitchen

On Wednesday, July 17, 2024, the water board celebrated the official start of the construction and renovation of the sewage treatment plant (STP) at Gaarkeuken. The Noorderzijlvest water board is building a new sewage treatment plant in Gaarkeuken. This will eventually replace the old plants in Marum, Gaarkeuken, and Zuidhorn. Cleaner water, better for the environment, and less odor and noise in the surrounding area. All information about the project can be found on our website created specifically for the Westerkwartier WWTP project: RWI Westerkwartier

The old sewage treatment plants in Marum, Zuidhorn, and Gaarkeuken are outdated. That is why a new treatment plant is being built in Gaarkeuken. Gaarkeuken will become the central treatment plant that will take over the functions of the other locations. The locations in Marum and Zuidhorn will eventually close.

New sludge cake transfer

On Friday, May 24, construction began on a renovated sludge cake transfer station at the sewage treatment plant (STP) in Garmerwolde. The construction of a new sludge cake transfer facility stems from a desire for renewal. On the one hand, the water board is striving for innovation, energy savings, and more efficient transport of sludge to partners who take care of the final processing of the sludge. On the other hand, these innovations result in less traffic, which is positive for all residents living near the Garmerwolde WWTP. 

The new sludge cake transfer facility will reduce energy consumption by approximately 30 percent compared to the current installation. In addition, the loading of sludge into trucks will be further optimized. The trucks are placed on a weighbridge, allowing them to be loaded with great precision. This means fewer trucks on the road, which is better for all local residents. Because the construction mainly involves building upwards, a lot of space is saved on the site of the wastewater treatment plant in Garmerwolde. The new transfer system is a so-called closed transport system. This means that employees will have less contact with the sludge cake. This makes the new working environment safer for staff.

The new sludge cake transfer system will be put into operation at the beginning of 2025. More information Festive completion of sludge processing investment projects at the Garmerwolde wastewater treatment plant

We started this year with heavy rainfall and a peak in water levels in our area. The pumping stations and weirs were running at full capacity to drain all the water via Lauwersmeer to the Wadden Sea. The high water levels led to some local disruption in early January. This included placing sandbags at a campsite on Leekstermeer. 

Due to the nuisance, overflow areas such as the Lettelberterpetten and the Lettelberterbergboezem were also used. These areas can temporarily collect excess water. The situation was manageable and not extreme. It was therefore not necessary to use the water storage facilities. 

On January 5, the water level dropped rapidly and we were able to continue draining the water effectively. 

In May, severe weather made it necessary to run the pumping stations at full capacity again. In the northwest of our working area, there was very heavy rainfall, with more than 90 mm of water falling within an hour. Fortunately, we were able to quickly pump away the excess water using our De Waterwolf pumping station. 

In June, water levels were also elevated due to heavy rainfall. Draining excess water takes time. The De Waterwolf and HD Louwes pumping stations were running at full capacity, as were all the polder pumping stations. 

The Drie Delfzijlen pumping station was being renovated and electrified at the time of the heavy rainfall. As a result, the emergency plan was put into effect. Two pumps were installed at Bronssluis/Slimsluis in Garmerwolde to pump the excess water from the Damsterdiep to the Eemskanaal. 

At the end of the year in December, we were once again talking about elevated water levels. However, by operating the pumping stations at full capacity, everything remained under control. 
 

Water retention in the Kop van Drenthe region

In the Kop van Drenthe region, we are working on a future-proof water system that prevents problems such as drought and flooding as much as possible. Our goals are: To make the water system more natural.
To improve the area's water retention in wet and dry periods.
Strengthening biodiversity by creating favorable conditions for more plant and animal species.
Connecting and strengthening green (nature) and blue (water) zones.
Making the area resistant to extreme weather conditions.
Making agriculture future-proof.

Four studies were conducted in 2023 and 2024. These describe the current situation in the Kop van Drenthe for the water system (the ISA), nature (the LESA), agriculture, and the landscape (AAC – archaeology, geological values, and cultural history). We summarize them below.

In 2025, we will continue to work on this wonderful collaborative project. You can read more on the Kop van Drenthe page. 

Pumps, weirs, and locks

Did you know that we use pumping stations, weirs, and locks extensively in our area to manage the water system? Below is an overview of the number of pumping stations, weirs, locks, and more: