Hydrography Data Stewardship for The National Map: What It Is and Why It Matters

Two national datasets

The National Hydrography Dataset (NHD) and the Watershed Boundary Dataset (WBD) were designed and filled in by a large group of agencies that work with hydrography across the United States, led by the U.S. Geological Survey (USGS), the U.S. Environmental Protection Agency (EPA) and the Natural Resources Conservation Service (NRCS).

The NHD's flow network, attributes and linear referencing support extensive scientific analysis. It is well suited to cartography — it feeds the US Topo map series — and is on the Geospatial Platform, which shares trusted geospatial data, services and applications with agencies, their partners and the public. Scientists and managers use the WBD's watersheds to define distinct drainage areas.

Demand keeps growing for data that are more current, more detailed and better described, so both datasets need continuous maintenance. The people who know best how local streams and lakes are changing are those closest to them — state and local governments, federal land management agencies and other users. That need for local knowledge led to a collaborative stewardship process for revising and maintaining the NHD.

Why states take part

State agencies that serve as stewards describe what they get from it:

• Arkansas — The Arkansas Department of Environmental Quality, like many state agencies, depends heavily on the NHD for its water work, and agencies cooperate to keep it current for statewide needs. Stewardship keeps the state's hydrography up to date on The National Map and makes the NHD a foundation for combining data and managing water. The department has adopted it as the base for the state's surface-water quality standards (Regulation No. 2 of the Arkansas Pollution Control and Ecology Commission), its impaired-waters (303(d)) list and other water documents.
• North Dakota — A state agency often sits between local and federal land programmes. The Department of Health runs the nonpoint-source pollution control programme, a watershed-based effort that passes EPA grants to local groups for projects that cut runoff pollution. The Game and Fish Department uses sixth-level WBD hydrologic units for its "Save Our Lakes" programme, and the Wildlife Division's Private Lands Section uses them for land-use inventories.
• Idaho — As a steward, the Idaho Department of Water Resources works with the USGS to make an NHD that serves local, state, regional and national users. An updated NHD helps with interstate water compacts, Columbia Basin treaties and ground- and surface-water issues with neighbouring states; keeping local hydrography current and correct makes it easier to administer water rights and settle disputes. The department contributes local knowledge and works with the USGS, other state stewards and users to make the NHD a GIS layer that works for Idaho.
• Florida — For the Department of Environmental Protection, the NHD is the common thread linking Total Maximum Daily Loads, Basin Management Action Plans, numeric nutrient criteria, water-quality reporting to EPA and many maps. Stewardship has helped the department lead in several water programmes; updating the NHD directly improves resource management and builds working relationships among state, regional, county and city agencies and private firms and non-profits.

How stewardship works

Stewardship lets local users who know the hydrography update the data. Because the NHD and WBD are authoritative sources, a steward must have the technical skill and impartiality to represent an area's hydrography faithfully.

• The agreement. A Memorandum of Understanding (MOU) is signed between the USGS, as national data coordinator, and a principal steward for the state — often a state agency with a lead role in water. One or more substewards may supply updates under the principal steward. The MOU sets out each party's duties.
• The principal steward is the main contact between the USGS and the state's maintenance work. It rules on the data substewards provide, to give the most accurate picture of the state's hydrography, promotes the datasets and makes them publicly available in the state.
• The USGS sets standards and handles data management, quality assurance and distribution. It assigns each state a point of contact and provides the training and resources to run the editing process.
• The tools. The NHD and WBD Update tools walk stewards through each step of editing, enforce the database's rules and run full quality control to protect the data's integrity. They are updated as the technology and datasets change.

Getting involved

• To help maintain the NHD or WBD, contact the USGS through the state map at nhd.usgs.gov/stewardship.
• NHD data, information, tools and tutorials are at nhd.usgs.gov.
• The stewardship programme's site was at usgs-mrs.cr.usgs.gov/stewweb.

Sources

• Arnold, D., 2014, The National Map hydrography data stewardship—What is it and why is it important?: U.S. Geological Survey Fact Sheet 2014–3084. https://pubs.usgs.gov/publication/fs20143084 — the state agencies' statements paraphrased; its two landscape photographs, credited to named photographers, are not reproduced; rewritten in hubnx's own words.