Hydrography Committee - Surface Water Subcommittee
The Governor's Council on Geographic Information
Meeting Notes November 20, 1997
AGENDA:
A. Introduction to Subcommittee
B. Surface Water Hydrography Data Layers: What do we have?
C. What do we need?
(spatial representation accuracy, connectivity, identification, attachment of point and segment attributes, upstream/downstream relationships, lakes, wetlands, and Protected Waters)
D. How do we go about getting it?
The purpose of the meeting was to familiarize everyone with the surface water hydrography databases currently in use in the state, and with databases under development. As background materials, metadata was distributed for the surface water layers listed on the agenda. Agencies reported on their needs for hydrography data, and on their data development activities.
Mark Ebbers of DNR Fisheries reported on a project in Fisheries to enhance the DOT basemap hydrography layer, with an emphasis on areas containing trout streams. DNR had a handout and a status map describing the process. The first priority is trout waters (450 of the state’s 1740 quad sheets contain trout waters), with the rest of the state to follow. Entire watersheds will be completed. DNR initially completed 200 quads, and has a contract with St. Cloud State University to do another 300 quads.
Ebbers and Mark Wald (formerly of DNR, now with OSM) described the fixes and updates which were done, initially using the DOT Basemap hydro data, and also adding lake information from the national Wetlands Inventory. DNR is interested in doing more than the trout stream areas, given additional funding or cooperators.
Mark Olsen from the Minnesota Pollution Control Agency’s Information Systems Office described work MPCA is involved in with on the National Hydrography Dataset (NHD), being jointly developed by the United States Geological Survey and the U.S. Environmental Protection Agency. NHD is a national cooperative effort to bring together the USGS 1:100,000 Digital Line Graph linework with the Reach Numbering System (RF3) of EPA. USGS has created a feature-based model which would tie together the major hydrographic databases at the national level.
The linework of the file is the USGS 1:100,000 DLG Hydrography layer. USEPA adds Reach coding from RF3, and attribute information for each reach which provides "connectivity" intelligence. Many states are involved in the development of this file, including the MPCA in Minnesota. RF3 is a critical file to state agencies such as MPCA which report to USEPA under the Clean Water Act. The work MPCA is doing is the ‘visual pass’, which adds the reach attributes to the DLG, checks for physical connectivity, and adds river centerlines where necessary. The NHD consists of a data model which is designed to allow higher-scale data to be added to it.
The group created a draft list of needs for a surface water hydrography file. The needs ranged from the general to the very detailed, and referred to rivers and lake/wetland basins. The list is an evolving document and is available from LMIC upon request.
The group felt that there was a need to get a better understanding of the two efforts identified above, in order to be able to define the state’s current need and the role of the federal data set in Minnesota’s activities. A fuller presentation of each of these efforts will be scheduled for the next meeting. The resolution of the river numbering issue will be saved for a later meeting. After the presentations, the group will try to refine the needs list, and to being to formulate a plan to create the layer. Funding proposals will also be discussed.
The next Surface Water Subcommittee meeting will be Jaunuary 7, 1998.