Background

Watershed boundaries had been delineated by several state and federal agencies over the years but no attempt was made in the early stages to coordinate these boundaries. The Nebraska Natural Resources Commission contacted all of those agencies known to delineate watersheds and coordinated an effort to combine these delineations into one GIS database. These agencies included the Nebraska Natural Resources Commission, Game and Parks Commission, Department of Water Resources, Department of Environmental Quality, Conservation and Survey Division/UNL, U.S. Geological Survey, and U.S. Natural Resources Conservation Service. A meeting of all of the interested parties was held to discuss accuracy, QA/QC, projections, and procedures.

As part of the process, one stream reach for each delineated watershed was also digitized. The GIS database created as a result of this process is referred to as the Major Streams of Nebraska. Upstream and downstream linkages were defined and each stream was linked to its appropriate watershed to allow tracking the flow of watershed runoff. Locations of stream flow gaging stations are also identified.

The results of the project had been reviewed by all participating organizations. Through cross-correlation tables, all watershed boundaries can be plotted individually or combined.
 

Issues

1. Identify primary Stakeholders in this particular priority database category.
 

2. Initial assessment of current status of database versus perceived need.

Current Status:  The NRC has developed Hydrologic Units (Watersheds), and Major Streams databases (coverages) of Nebraska, which were digitized from the USGS 7.5 minute topographic paper maps.

Perceived Need:  The Hydrology coverages are used for watershed planning, forestry planning, whole farm and ranch planning, stream degradation studies, river basin studies, flood plain management, assistance and mitigation as well as natural resources project reviews and evaluations. The NRC in consultation with NRCS, DEQ, G&P, DWR, and USGS completed this comprehensive watershed coverage. As part of this process, a Major Streams coverage was also created that relates to the watersheds. Water surface elevations are part of the attributes of this coverage.
 

3. If it appears to be warranted, draft for the GIS Steering Committee's consideration a proposal for the creation of a subcommittee to develop recommendations for achieving the Database Goal objectives for this priority geospatial database category. Please address the following issues:

1. Are there major deficiencies in the currently available database? In general, what are they?
 
• The watersheds were delineated from USGS 1:24,000 contour paper maps, some of which are 40+ years old.

 
• In a few cases that scale of map was not available and others (up to 1:500,000 in adjascent states) were substituted.



•  The data is considered accurate within 50 meters in Nebraska with lesser accuracy in the surrounding states.


2. Recommendations for groups that should be included in a study subcommittee?


No additional study is required at this time.


3. Are revised standards needed? In what areas?


No additional study is required until higher quality maps become available.


4. Are there outstanding maintenance or integration needs to be addressed?


As additional delineations are identified, NRC coordinates with the requesting agency to make the needed modifications. No additional funds or technologies are needed for any maintenance issues.


5. What is the estimated timeline that will be required to define a proposed action plan (for the Steering Committee's consideration) to achieve the Database Goal objectives for this database category?


This is a completed project.


6. What are the anticipated resources that will be required to conduct this study? Are they available?


None


7. Other Issues:


For any questions, suggestions and comments, please contact the Nebraska Natural Resources Commission:

Mahendra Bansal, 402-471-3964
Rich Kern, 402-471-3948
FAX: (402) 471-3132
Website URL: http://www.nrc.state.ne.us