Mowing watercourses

Aquatic plants are important for water quality. They stabilize the soil, absorb light and nutrients, and provide shelter for amphibians, insects, and fish. However, too many aquatic plants rooting in the soil and growing up to the water surface can obstruct the flow of ditches. To limit flooding and water shortages (during droughts), we mow aquatic plants and reeds from our 6,000 kilometre ditches. 

How is mowing done?

During the work, we adhere to the 'Code of Conduct for Sustainable Management and Maintenance for Water Boards'. This means we take protected animal and plant species into account. Where there is enough space for water to flow, as many plants as possible are left standing. Mowing is done from the shore using a crane or tractor. In wider waterways, a mowing boat is used. Approximately 25% of the aquatic plants are left standing to promote biodiversity. The cuttings are left on the bank for at least two days so that the aquatic animals can return to the water. In urban areas, we clear away the cuttings; in rural areas, they are left in place as much as possible. We mow reeds in phases, clearing about one-third of the total reed beds each year. Mowed reeds are always cleared away.

When will the grass be mowed?

From June 15 to July 15, we mow in urban areas; from July 15 to August 1, in rural areas. This leaves approximately 25% of the aquatic plants standing on one side of the ditch. This is because animals hide among the aquatic plants, and we want to disturb them as little as possible. The second mowing round takes place in September/October. At that time, we mow the other side of the ditch only in locations where it is necessary for the flow. Because Hollands Noorderkwartier is a large area, it is difficult to say in advance exactly where the contractors will be working. A tip for private individuals with a pump in the ditch is to remove it from the water or mark it with a stake so that the operator can take this into account.