Landgoed Vereniging Golfclub Cromstrijen

GEO Certified® 02/2015 GEO Re-Certified 02/2018
Telephone: +31(0) 186654455

Executive summary (English & local language)

With its 68 hectares, this 18-holes course and compact course (9 holes, pars-3 and pars-4, B-status) is not particularly large, but it looks spacious. After its construction in 1989 there were several adjustments, such as the recent reconstruction of holes 7 and 17 (2011-2014). Framed by dykes, this course has a polder course character. It is situated 1 km from the village of Numansdorp and one of the neighbours is a marina on the Hollands Diep waterway. The ground is leased. With the course’s location comes a number of fixed, unchangeable facts that have a decisive influence on the course: the heavy clay soil, the salination, the often powerful winds, noise pollution from the A29 highway, the dyke along the Hollands Diep that will be heightened, and the nearby and dominant wind turbines.

The club has a firmly anchored GEO committee of 10 members. A permanent core of 3 highly involved committee members takes care of implementation and communication of the sustainability pathway. The committee maintains good relationships with the board which was renewed at the end of 2014. The committee sees this as a new impulse for the pathway and makes sure that the board keeps supporting GEO 100%. The head greenskeeper, who was hired shortly after the course was first constructed, has a pivotal position in this respect. His professional expertise and knowledge of the area are very broad and he is entrusted with a lot of responsibility. The club trusts him greatly. Sustainability comes natural to Comstrijen, something that the fact that the head greenskeeper is a member of the NGF Sustainability Committee attests to.

Deze 18 holes baan annex 9 holes compact-course (par 30) is met 68 ha niet groot maar oogt ruim. Na de aanleg in 1989 zijn er aanpassingen geweest, waarvan de reconstructie van de holes 7 en 17 het meest recent (2011-2014). De baan, ingekaderd door dijken, heeft het karakter van een polderbaan. De baan ligt op 1 km van het dorp Numansdorp en grenst aan een jachthaven aan het Hollands Diep. De grond wordt gepacht. De situering van de baan impliceert een aantal vaste gegevens waar niets aan veranderd kan worden, maar die wel een stempel drukken op de baan: de zware kleigrond, de verzilting, de vaak harde wind, geluidshinder van de A29, de dijk langs het Hollands Diep die verhoogd gaan worden en de nabijgelegen dominante windmolens.

De club heeft een stevig verankerde GEO-commissie, die bestaat uit 10 leden. Een vaste kern van 3 uiterst betrokken commissieleden draagt zorg voor de implementatie en de communicatie van het duurzaamheidstraject. De commissie onderhoudt nauwe contacten met het bestuur, dat eind 2014 vernieuwd is. Zij zien dit als een nieuwe impuls voor het traject en zorgen dat het bestuur 100% achter GEO blijft staan. De headgreenkeeper, kort na de aanleg werkzaam op de baan, speelt hierbij een cruciale rol. Hij heeft een brede vakkennis en gebiedskennis en krijgt een grote verantwoordelijkheid. Het vertrouwen in hem is groot. Duurzaamheid is vanzelfsprekend voor Comstrijen. Dat headgreenkeeper zitting heeft in de Commissie Duurzaam!Golf (NGF) zegt genoeg over de motivatie.


The course design references the old Hoeksche Waard landscape: a old sea clay polder in the Dutch delta. The Hoeksche Waard became an island after the 1421 St. Elisabeth’s flood engulfed the area, and the waterways in the delta changed drastically.
On the side of the golf course, the Hoeksche Waard is bordered by the Hollands Diep canal, whose embankments with their salt marshes and willow coppice lands have high nature values. The Hollands Diep and the adjoining Haringvliet are designated Natura-2000 areas; the marshes and willow lands are part of the Nature Network in the Netherlands (EHS). Many birds visit the course from these wetland natural reserves. The course derives its identity from a large, central body of water with natural woods surrounded by creeks and historic clay pits, bank vegetation, coppice shrubs, pollard willows and clusters of trees. The natural forest around the historic clay pits has been designated as a sanctuary. The course is framed by dykes on three sides: the quay along the Hollands Diep, the Molendijk embankment and the dykes of the A29. These endow the course with a clear landscape framework.

The course consults a lot of organisations and expert advisers. The course architect and managers collaborate intensively to safeguard the course’s identity.
The monitoring plan is part of the management plan (2011). The work groups of the Hoeksche Waard Landschap association support the course in stocktaking. Based on baseline measurement, 9 PQs were selected for annual inventory – these are mostly spots with the greatest orchid population. There were extensive breeding bird censuses between 2012 and 2014, which showed that there are no fewer than 42 breeding species, including a number of vulnerable species (kingfisher, house sparrow, common redstart, and green woodpecker). There was an inventory of butterflies, dragonflies and flora in 2014; the fish stocks were measured in 2013.

The most characteristic species of trees are the elm, willow, poplar, and alder. To compensate reconstruction of hole 7, the course planted dozens of native tree species and hundreds of scrubs, which also function as a buffer along the highway. The 60-year old poplars are suffering from old age but will remain untouched as long as they don’t pose a danger. New poplars are planted in phases to preserve the landscape image. Water and banks are very important to the local nature. The water embankments and coppice woods are home to many orchids of 4 and 2 species respectively.

The grass composition was attuned the local availability of nutrients and water. Agrostis stolonifera is planted on the greens, festuca rubra on the tees, and a combination of lolium perenne and poa pratensis on the fairways. A thick thatch layer led to an invasion of Poa annua, which was successfully fought off by regular airing the bald spots on the greens, by filling with sand, and by sowing agrostis. The target is to have 70% agrostis. The thatch layer issue is now under control. Yellowing of the grass is accepted as long as it does not affect the quality of the game.

Nature is offered all the space it needs; almost 50% of the course’s area is managed as nature. The GEO committee adjusts the size of the nature rough, which is mowed extensively, every year, and it has grown in size since 2011. Reconstructing hole 7 – in combination with hole 17 – resulted in 1 ha of additional wetlands (also water storage basin), a nature island, and a border of native tree species and shrubs along the highway.
Management is guided by the management plan (2011), an integral and very thorough report which designates areas of potential and offers an annual planning. There is no long-term planning and the 2011 version has not been updated. The set goals of the management plan are evaluated every three years. They are currently working on an extension with a GIS system.
Continuing the current management of the orchid-rich grasslands between fairway and embankments is the best guarantee to maintain this wealth of flowers. Consistent management requires working with Codes of Conduct. The reeds are mowed in phases. Reed banks do not pose any issues, but the lines of sight are kept open. There is a danger of the small, shallow pools getting congested with reeds and losing their value. The nature island with kingfisher wall has been a great success. The 40 nesting boxes, which are maintained annually, have been spread out of the area. Recently, a work group for the common swift was set up.


The ground water level is fixed by a barrage issued by the water level ordinance of the water authorities. During long bouts of rain, the course has to be shut down. This mostly occurs in winter.
At the moment, the course still drains surface water to the Hollands Diep using a main pump and two distribution pumps. This is brackish water which has to be acidified and filtered by mussel seed. There is a unique plan to use the effluent of the neighbouring water treatment plant to sprinkle the course. This would link two local interests and solve the issue of the increasingly salt water of the Hollands Diep, which will salinate further from 2018 onwards, following the decision to leave the sluices in the Haringvliet open at high water, to improve the fish populations. There are some environmental hurdles to be taken before this sprinkling plan can be implemented.

Consumption of public water in the clubhouse, administration, greenskeeping, and sanitary facilities on the course is normal, but slightly on the increase. This can be explained by the growing number of members and guest players. The inflow of surface water is small and constant. This water is also used to hose down machines, in combination with compressed air.

Sprinkling water is pumped from the Hollands Diep because the ground water and course surface water are too salt due to the brackish marsh. The water is buffered in a water silo and then acidified with hydrochloric acid; too high pH values decrease the quality of the grass. A mussel seed filter prevents clogging of the drains. There is a total of five pumps that pump in water, fill the water reservoirs, mix it, and keep it pressurised. The sprinkling is subject to soil moisture measurements. The fairways are only sprinkled in periods of drought.

There is a preventive wetting agent policy for the greens, pre-greens and tees. A moisture meter assures the right dosage. Showers have been fitted with a timer. Staff is informed to boost water consumption awareness. There is an action plan to further decrease public water consumption.


The club is well informed about the energy consumption and is always looking for ways to reduce it. There is a continual weighing of costs and savings. The environmental care plan offers plenty of points to further decrease consumption and investigations into the opportunities for renewable energy. Insight into consumption is offered by an energy scan conducted with a local installer.

Electricity consumption is relatively high, with a peak between April and July, caused by the sprinkling pumps. There are five meters and the reads are recorded vigilantly. Gas consumption is average. The diesel consumption is high, caused by the intensive management that this fertile soil requires.

Electricity is purchased from fossil fuel suppliers. Switching to clean energy is not financially feasible due to the favourable rates under the current contract. The opportunities for generating power on site are limited. The course does not wish to erect wind turbines, but there are possibilities to generate solar power. The roof of the driving range cover faces the south, has a favourable angle, and offers room for almost 200 m2. The use of biodiesel is considered when purchasing new equipment, and the course is very positive about the two hybrid machine mowers. Electric mowers offer several advantages: no emission (in case of renewable energy); no need for oil; and no noise pollution.

In the past few years there have been several initiatives, such as timers for the outside lighting and fountain. Sensors have been installed where they are useful. Energy-efficient lights were installed when the kitchen and restaurant were renovated. There is no lighting on the outside terrace. The 2800-Watt lighting on the driving range has been fitted with a timer. The buildings are properly insulated. Staff is informed about use of energy, raw materials, and machines.

Supply Chain

The course uses little pesticides and fertiliser and there are hardly any opportunities to further reduce this. Knowledge about the club’s suppliers is not complete yet (origins, certificates, eco labels). There is still something to be gained by getting a better handle on suppliers (origins, production process, certificates, packaging, frequency of deliveries, central purchasing). Transport is already decreased by the use of a distribution centre.

The market is closely watched. When machines and tools are replaced, the electrical options are taken into consideration. The hybrid mowers have garnered a lot of praise. The club is very aware of Big Bags, green land certificates, and local and central purchasing. These have some influence on the purchasing policy, but the price-for-quality ratio is still the decisive factor.

By buying locally and consciously, the course has an influence on the economy and contributes to awareness and a better economy. The restaurant is leased and there is an effective coordination with the leaseholder, who pays attention to seasonal and local products and buys from local suppliers.

The use of pesticides (fully inorganic) is relatively low, especially on the tees. The club is still exploring ways to further decrease it. Agrostis is becoming more and more dominant, resulting in lower fertiliser needs and less frequent mowing.
Herbicides are used on the fairways and roughs; fungicides and incidentally insecticides are used on the greens and tees. There is plenty of awareness about the upcoming ban on plant protection products and preparations to comply are underway.

The club has a central collection zone for separated waste, which is frequently picked up by certified companies. In the past, wood chips were used in the flowerbeds, but they are now collected and shipped in large volumes. Clippings, collected in the green container, are also transported and processed externally. Fairway clippings are left where they are.

Pollution Control

Fertiliser, water, and pesticide consumption levels are low, leading to a correspondingly low environmental pressure. The club meets the minimal legal requirements and is inspected for this annually by the municipality. An environmental care plan underlies policies and ensuing actions. The subjects are: waste separation and processing, fertilisers, fuels, and hazardous materials.

The water quality is tested for chemical parameters at the point of inflow annually.

The clubhouse and water runoff system are connected to the sewer. The same contractor cleans the grease traps once a year.

Hazardous materials are stored in a suitable room, which is properly ventilated. The room meets all legal requirements.

Tanks are filled, and machines are tanked, stored, maintained and hosed down above a large, completely impermeable concrete floor above an oil-repellent layer. The double-walled diesel tank dates from 2005 and replacing it is currently being considered.

There is a sanitary building on the course which is connected to the sewer. Diseases and pests are battled where they are found. Spraying pesticides is limited to a minimum, and nozzles are adjusted for weather type and substance. This limits the environmental impact. There is no spraying on the bodies of water and the nature rough (no-spray zones).


The success of sustainable course management is in part a result of the involvement generated among the members. This is done through several media. The club has drawn up an extensive communication plan. The new board (end of 2014) is open to continuing with the set sustainability course.

The course employs 19 contracted persons (management, greenkeeping, catering, golf coaching). All 6 greenskeepers have completed an education which paid attention to ecology, and attended courses on Flora and Fauna Legislation in 2013. There are plenty of people with First Aid and emergency response diplomas. The club strives to improve developments by introducing the POP personal development plan.

The environment work group comprises the golf manager, committee members and representatives of the local environmental organisation. The work group has registered all data in an orderly, thematic system. It is becoming more and more difficult to staff the committees; the pressure on volunteers is continually increasing – a bottleneck issues plaguing many golf clubs.

There is regular contact with the neighbours concerning shared interests (former tram depot, visitor centre ‘National Landscape Centre’, Hollandse Delta water authorities).
Local governments are involved in the matters surrounding the sustainability certificate. Local environmental work groups (the national Forestry Commission and workgroups of the Hoeksche Waards Landschap association) are informed on current developments and involved in inventories. Nearby schools use the golf practise facilities. Local businesses sponsor the club and frequently use its facilities.

One of the club members wrote a slim volume on the history of the golf club. Due to its past as a polder, the course still has some historic relicts, including pollard willows and historic clay pits. The nature forest is a cultural-historical element that is maintained and supported. Coppice wood has been brought back.
The club was awarded the ‘country estate’ status in 2013 (‘Landgoed Vereniging Golfclub Cromstrijen’ – Country Estate Association Golf Club Cromstrijen), which means the club has an obligation to maintain the natural values.

There are currently no legal disputes or planning procedures. The club is closely involved in the strengthening of the dyke which will have an effect on the course. The attitude towards this matter is a positive one.

An information sign about the history of the polder and the reconstruction was installed after hole 7 on the competition course was reconstructed. In the season, small signs and the website point out the wealth of orchids to members.

The golf club participates in the annual NGF open house day and in the Bird Watching Day.
Hoeksche Waard Landschap (association for nature preservation, environment, and historical village character in the Hoeksche Waard) deploys its work groups from time to time, for instance for inventories that are held in collaboration with club members. This exchange strengthens both parties. The website offers information on GEO and the sustainability objectives, although there is little to be found on nature and landscape.

Documentation Reviewed


This 25-year old course has an obvious landscape character that connects well to the landscape of the Hoeksche Waard. The framing by dykes is very characteristic. There is a central body of water that was inspired by the creeks that used to run here. Combined with the nature forest around the clay pits and the new nature island, there is a sound foundation for a rich environment. The plethora of orchids is a vulnerable landscape quality that the club is very aware of. Great steps have been taken in the fields of energy and raw materials. The club is focussed on the future; there are a lot of plans for the coming years and these are sure to be executed.

Certification Highlights

The club has grasped the essence of sustainability. Necessities are turned into virtues and the club finds inventive solutions for difficult issues; examples are the brackish water and the poor draining of the clay soil. A unique accomplishment is the deal struck with the Holland Delta water authorities to use the effluent of the water treatment plant for sprinkling. Cromstrijen acts on many forefronts. The club is represented in the NGF Sustainability Committee and is considering joining ‘Sustainable Golf Course Management’ that was founded by the clubs. Finally, the club also takes part in ‘Sustainable Hoeksche Waard.’

The cultural-historical landscape has been beautifully interwoven with the holes. The club takes pride in the landscape and maintains its knowledge on the subject. They have even planted new coppice wood. The reconstruction of hole 7, on the flanks of the historic clay pits, was done respectfully. Members receive information on nature and landscape here.

The botanical wealth in the zone between water and fairway is quite unique. By treating this area carefully and finding a proper balance between nature and golf, the club has succeeded in increasing this wealth. A professional monitoring of the most vulnerable flora, using 9 PQs, ensures that this area is closely watched.