Introduction
The Roseau River Watershed District received a grant from the Northwest Minnesota Foundation to collect and inventory culvert location within the boundaries of the watershed district. The purpose of the inventory was to produce a dataset to improve decision making and modeling capabilities related to drainage and flooding. The data will also provide local government units with a catalogue of the dimensions and condition of all identified culverts within their jurisdiction.
Background
A culvert inventory was completed in 1999 collecting data from Stafford and Jadis township within Roseau County. The information from this inventory provided a snapshot of local drainage within the watershed district and the county, and illustrated the need to collect data related to drainage infrastructure within the entire district. The Two Rivers Watershed District located in the western portion of Roseau County and most of Kittson County completed a culvert inventory between 1997 and 2008. Two Rivers has used the data collected to settle landowner disputes, aid in future project planning, assess drainage infrastructure and improve hydraulic modeling. The Roseau River Watershed District proposed a comprehensive culvert inventory in the fall of 2013. The District recognized the need for a complete dataset to assist in both short term needs and long term planning efforts. The Northwest Minnesota Foundation (NWMF) was approached to secure funds to complete the proposed inventory. Funds provided from the NWMF supported a intern staff position, field staff time and travel
Methodology
Field staff collected the data using a GeoExplorer 6000 series Trimble unit on a 2 meter staff, allowing greater precision collecting elevation and horizontal data. Information regarding the culvert length, Upstream/downstream, condition, ownership, end type, restrictions, the date and the person collecting the data were recorded in the field and verified in the office. Data was collected in the field during the summer of 2014 and 2015, data Culvert length data was entered into the shapefile attribute table using ArcGIS to measure the distance between the two end-points collected in the field. Upstream and downstream designations for culverts were primarily entered in the field, for problematic (flat) culvert location flow accumulation data from ArcMAP were used to determine upstream and downstream ends of culverts. Culvert condition refers to if the pipe has been damaged or is in need of some maintenance, the attribute table provided a comment column to provide additional information regarding culvert condition or any other details pertinent to that site. The Ownership and maintenance fields provide information regarding whether the culvert is public or private and if public which entity is responsible for the culvert. The date of collection is automatically recorded by the Trimble unit and the surveyor identification is entered upon closing each file, data provided from public agencies were identified as said agency in the surveyor field.
Results
4,674 culverts were identified within boundaries of the Roseau River Watershed district. 4,493 culverts were identified within Roseau County, 95 within Kittson County, 45 within Marshall County, 20 within Lake of the Woods County and 21 culverts in Beltrami County. 402 (8.6%) pipes within the Watershed district were identified as needing some form of maintenance performed or replacement required. Distribution of culverts needing maintenance or replaced was even throughout the watershed district. 129 (2.7%) culverts were identified as having traps or gates, trapped or gated culverts are primarily concentrated downstream on the City of Roseau. Culvert locations and alignments will be utilized for hydro conditioning digital elevation models used to address water related issues within the district. The known locations and condition of the culverts will improve precision of future modeling efforts. The Spatial Dataset will be provided to the County Highway Dept, the Roseau County SWCD and the Watershed's consultants. Data will be publicly available free of charge to any individual or entity that requests a copy. The Watershed District will annually update the dataset based on projects, permits or other known activities that add, remove or change the characteristics of culverts within the jurisdiction of the Roseau River Watershed District.
