Summary
Summary
The Holter-Hammrich project combined several natural water retention measures: floodplain restoration, meadow and pasture rehabilitation, and reduced tillage. Located in north-west Germany within the Weser river basin (DE4000), it supports Lower Saxony's otter and wetlands protection programs and contributes to WFD goals. Since its implementation, the 240 ha flood retention polder—activated in 2011—has enhanced flood protection and become a key habitat for over 60 bird species and other wildlife, including the returning European otter. It now also serves educational and recreational purposes, with a 7 km nature trail and observation points. The project stands out for its integration of ecological, hydraulic, and public engagement goals, achieved through multi-stakeholder cooperation involving environmental agencies, water managers, local authorities, and farmers.
Photo gallery
Overview
Year of issue
2025
Project
NWRM
Implementation status
Completed
Contact
Tamer Fawzy, BEF DE
Location of the project
The Leda-Jümme area is a flat, broad valley of the lower Ems river.
Country
Germany
NUTS2 Code
Weser-Ems
Sponge measures implemented in the case study
Wetland restoration and management
Cover crops
Meadows and pastures
Floodplain restoration and management
Minimum tillage
Involved partners
| Authority type | Authority name | Authority role | Comments | Authority responsibility |
|---|---|---|---|---|
| Regional / sub-national water authority | Lower Saxony Water Management, Coastal Defense and Nature Conservation Agency (NLWKN) | Implementation | Promoter, developer, supervisor | Responsible |
Site Information
Climate Zone
Cool temperate moist
Temperature (°C)
9.00 °C
Slope range
0%-1%
Vegetation class
Grassland
Design and Implementation
Project scale
Micro
Project scale specifications
Subarea "Leysser Hammrich" (143 ha), Habitat for grassland birds
- landuse with different requirements (extensification)
- use of controlled water level increase in winter and spring
Subarea "Altes Tief" (80 ha) diverse mosaic of shallow water zones, shrubs, reeds and wet grassland - Mostly free vegetation development (succession)
- use of ca 40 ha year-round wet areas of shallow water
- landuse with different requirements (extensification)
- use of controlled water level increase in winter and spring
Subarea "Altes Tief" (80 ha) diverse mosaic of shallow water zones, shrubs, reeds and wet grassland - Mostly free vegetation development (succession)
- use of ca 40 ha year-round wet areas of shallow water
Project area
223
Area subject to Land use change or Management/Practice change (ha)
223.00 ha
Size
223.00
Size unit
ha
Design capacity
3800000
Principles
Integration of demands, integrative planning, functionality
Factor constraints
For the present area an independent concept has been developed that fitted the local requirements of nature conservation and flood protection.
Favourable preconditions
natural site conditions, in particular the height variations of the area
Financing
Total cost
12600000.00 €
Costs land acquisition
4000000.00
Costs operational information
€ 80,000 Technical constructions
€5,500,000 Specially prepared trail for nature information and experience
€3,000,000 New Roads for farmers
€5,500,000 Specially prepared trail for nature information and experience
€3,000,000 New Roads for farmers
Information on Economic costs - income loss
Actual income loss: Lease Agreements are given out for free, due to heavy regulations for farming
Policy and Governance
Policy description
Due to the natural site conditions, in particular the height variations of the area, the Holter Hammrich serves common goals of flood protection and nature conservation.
The closure of the last dike breaches, and the further expansion of pumping stations for drainage of the area led to new problems: After heavy rainfalls flood loads led to higher water levels, dykes were threatened to breach leading to floods at unpredictable places. More storage space was needed and finally built for excessive headwater.
Extensification or abandonment of agricultural use and high water levels in spring support an increase of characteristic breeding birds for example.
Amphibians benefit from standing water bodies.
The closure of the last dike breaches, and the further expansion of pumping stations for drainage of the area led to new problems: After heavy rainfalls flood loads led to higher water levels, dykes were threatened to breach leading to floods at unpredictable places. More storage space was needed and finally built for excessive headwater.
Extensification or abandonment of agricultural use and high water levels in spring support an increase of characteristic breeding birds for example.
Amphibians benefit from standing water bodies.
Policy targets
Improved Biodiversity
Target remarks
Flood control and flood risk mitigation
Nutrient Pollution
Biodiversity and gene pool protection in meadow areas
Habitat restoration
Nutrient Pollution
Biodiversity and gene pool protection in meadow areas
Habitat restoration
Policy pressure
| Directive | Relevant pressure |
|---|---|
| WFD identified pressure | Nutrient pollution |
| Floods Directive identified pressure | Natural exceedance |
Requirement directive
| Requirement directive | Specification |
|---|---|
| Other EU | Habitat Directive: Otter protection, habitat restoration |
Policy challenges requirements
The Lower Saxony otter protection programme and the Lower Saxony wetlands protection programme were aimed to be addressed.
Part of a wider plan
Yes
Wider plan
| Name |
|---|
| Lower Saxony otter protection programme |
| Lower Saxony wetlands protection programme |
Public consultation
No
Has contractual arrangements
No
Impacts and Monitoring
Monitoring System
Monitoring requirements
Regularly
Maintenance
Maintenance requirements
Maintenance schemes have not been set up. The state of Lower Saxony is contractual responsible for any maintenance required.
Impact Assessment Methodology
Performance impact assessment method
Unknown
Performance impact estimation information
N.A.
Socio-economic Impacts
Ancillary benefits
Biomass production, recreation, and information.
Biophysical impacts: Hydrology
Information on retained water
3.8 million m3
Information on increased water storage
N.A.
Information on runoff reduction
N.A.
Biophysical impacts: Biodiversity
Improved biodiversity
Yes
Information on improved biodiversity
Extensification or abandonment of agricultural use and high water levels in spring support an increase of characteristic breeding birds for example. Amphibians benefit from standing water bodies.
Biophysical impacts: Water & Soil Quality
Water quality overall improvements
N/A info
Information on water quality overall
N.A.
Soil quality overall improvements
N/A info
Information on soil quality overall improvements
N.A.
Biophysical impacts: Others
Ecosystem impact climate regulation
No information available
Information on ecosystem impact climate regulation
N.A.
Lessons Learned
Key lessons
A continuous and open discussion between all involved groups led to a high acceptance of the overall process. It was a key lesson of this measure that cooperation between different sectors (flood protection, nature conservation etc.) as well as different stakeholder groups (government agencies, NGO†™s) are able to cooperate in effective networks, when a consistency of goals is given.
Drivers
| Driver type | Driver role | Comments |
|---|---|---|
| Organisation committed to it | Main driver | The NLWKN is the Nature Protection Agency of Lower Saxony |
| Availability of subsidies | Secondary driver | — |
Success factors
| Success factor type | Success factor role | Comments |
|---|---|---|
| Communication activities | Main factor | A continuous and open discussion between all involved groups led to a high acceptance of the overall process. |
| Attitude of relevant stakeholders | Main factor | Willing stakeholders and a positive public perception were the major enabling factors. |
| Financing possibilities | Main factor | The availability of financial resources and cooperation between all stakeholders led to a smooth implementation of all measures. |
Flexibility / Adaptability
For the present area an independent concept has been developed that fitted the specific requirements of nature conservation and flood protection as well as the specific landscape. In similar settings, the technical dimension of the measure is adaptable.
Transferability
The most important precondition for a similar applications is a consistency and cooperation between different stakeholders, so that various financial instruments can be activated to achieve a common goal.
Sources
Sources