FACT SHEET

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Navigable Waters Protection Rule

Implementing the Navigable Waters Protection Rule

On January 23, 2020, the U.S. Environmental Protection Agency (EPA) and the Department of
the Army (Army) fulfilled yet another promise of President Trump by finalizing the Navigable
Waters Protection Rule to define "waters of the United States" (WOTUS). For the first time, the
agencies are streamlining the definition so that it includes four simple categories of jurisdictional
waters, provides clear exclusions for many water features that traditionally have not been
regulated, and defines terms in the regulatory text that have never been defined before. Congress,
in the Clean Water Act, explicitly directed the Agencies to protect "navigable waters." The
Navigable Waters Protection Rule regulates these waters and the core tributary systems that
provide perennial or intermittent flow into them. The final rule fulfills Executive Order '3788
and reflects legal precedent set by key Supreme Court cases as well as robust public outreach and
engagement, including pre-proposal input and comments received on the proposed rule.

The Navigable Waters Protection Rule protects the environment while respecting states,
localities, tribes, and private property owners. It clearly delineates where federal regulations
apply and gives state and local authorities more flexibility to determine how best to manage
waters within their borders. Assertions have been made that the new rule will reduce jurisdiction
over thousands of stream miles and millions of acres of wetlands. These assertions are incorrect
because they are based on data that is too inaccurate and speculative to be meaningful for
regulatory purposes. The final rule along with state, local, and tribal regulations and programs
provide a network of protective coverage for the nation's water resources.

GENERAL IMPLEMENTATION OF THE FINAL RULE

•	Certain tools, data and approaches to determining jurisdiction will facilitate implementation
in the field. This fact sheet highlights how the agencies intend to implement key aspects of
the final rule.

•	The agencies will typically consider all relevant sources of information when completing an
approved jurisdictional determination, which may include on-site observations, field-based
indicators of hydrological conditions, maps, remote tools, and reliable datasets that are
available for the waterbody under evaluation.

•	The availability, accuracy, completeness, reliability, and applicability of these various
methods, tools, and sources of information may vary regionally and for site-specific reasons.
The agencies are not mandating the use of specific data or tools to implement the final rule.

•	The agencies will continue the longstanding practice of evaluating waters based on the
weight of evidence from the best available sources of information available for that
waterbody.


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IDENTIFYING AND DELINEATING SURFACE WATER FEATURES

•	A variety of remote tools and resources may be used to identify the presence of a potential
jurisdictional waterbody on the landscape. For example, U.S. Geological Survey (USGS)
topographic data, state and local maps, aerial photography and satellite imagery, the USGS
National Hydrography Dataset (NHD), U.S. Fish and Wildlife Service's National Wetlands
Inventory (NWI) maps, or the U.S. Department of Agriculture's Natural Resources
Conservation Service (NRCS) Soil Surveys may be used to indicate the presence of a stream,
river or ditch; a lake, pond, or impoundment; or a wetland within the review area.

•	These tools were not designed to indicate the jurisdictional status of a waterbody, and
limitations associated with these tools often require field-verification for accuracy.

•	Selection of the specific, appropriate tool(s) and resource(s) will also depend on the type of
surface water feature under evaluation. For example, determining the jurisdictional status of a
ditch requires a determination of whether the ditch was constructed in or relocated a
tributary, or was constructed in an adjacent wetland, which may require the use of one or
more of the following data sources: historic maps and historic aerial photographs, local and
state records and surface water management plans, agricultural records, street maintenance
data, historic permitting and jurisdictional determination records, certain
hydrogeomorphological or soil indicators, wetlands and conservation programs and plans,
and/or data from functional assessments and monitoring efforts.

•	The agencies will also continue to use existing resources and methods to verify the presence
of potential jurisdictional waterbodies, delineate the boundaries of jurisdictional waters, and
determine the lateral extent of jurisdiction, where applicable. For example, the agencies will
continue to use the Army Corps of Engineers' (Corps) 1987 Wetland Delineation Manual to
verify the presence of a wetland and to delineate its boundaries. The agencies will also
continue to use the Corps' ordinary high water mark manuals, as well as any other applicable
guidance documents to determine the lateral limits of jurisdiction for tributaries.

DETERMINING PERENNIAL OR INTERMITTENT FLOW CLASSIFICATIONS

•	A stream or river, or other surface water channel, must be perennial or intermittent in a
typical year to meet the definition of "tributary" under the final rule.

•	The agencies have been using flow classifications to make jurisdictional determinations for
more than a decade. To determine whether a surface water channel is perennial or
intermittent in a typical year, the agencies may use a compilation of the best available
mapping sources, including the NHD or local maps, as well as other remote tools and
datasets such as aerial photographs, NRCS hydrologic tools and soil maps, desktop tools that
estimate the discharge sufficient to generate intermittent or perennial flow (e.g., a regional
regression analysis or hydrologic modeling), USGS topographic data, or modeling tools
using drainage area, precipitation data, weather, topography, land use, vegetation cover,
geology, and/or other publicly available information.

•	One example of a tool that could inform determinations of a channel's flow classification is
the USGS StreamStats web application, including the Probability of Streamflow Permanence

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(PROSPER) tool. StreamStats allows users to obtain estimates of streamflow statistics for
user-selected ungaged sites, and is available at: https://streamstats.usgs.gov/ss/.

•	In some cases, one or more site visits may be needed to perform on-site observations of
surface hydrology or collect field-based indicators of perennial or intermittent flow (e.g., the
presence of riparian vegetation, or certain aquatic macroinvertebrates). The agencies may
also use existing rapid, field-based streamflow duration assessment methods (SDAMs) that
use physical and biological indicators to determine the flow duration class of a stream reach.

o The agencies have previously used existing SDAMs developed by federal and state
agencies to identify perennial or intermittent streams, and will continue to use these
tools whenever they are determined to be a reliable source of information for the
specific water feature of interest. One example of an existing SDAM is The Streamflow
Methodology for Identification of Intermittent and Perennial Streams and Their
Origins, developed by the North Carolina Division of Water Quality, which is available
at:

https://files.nc.gOv/ncdeq/Water%200ualitv/Surface%20Water%20Protection/401/Poli
cies Guides Manuals/StreamID v 4pointll Final sept 01 2010.pdf.
o The EPA, the Corps, and the state of Oregon previously developed a regionalized

SDAM that has been validated for use throughout the Pacific Northwest since 2015 and
is available at: http://www.epa.gov/measurements/streamflow-duration-assessment-
method-pacific-northwest,
o The agencies are currently working to develop regionally-specific SDAMs for

nationwide coverage, which will promote consistent implementation across the United
States. As the agencies work to develop these methods, the agencies will provide
opportunities for the public to comment on the use of these methods, and seek scientific
peer-review, before regional methods are finalized. Additional information on the
agencies' efforts to develop SDAMs will be available on the EPA's website.

DETERMINING CONTRIBUTION OF FLOW DOWNSTREAM

•	A perennial or intermittent river, stream, or other naturally occuring surface water channel
must contribute surface water flow to a traditional navigable water or territorial sea in a
typical year to meet the definition of "tributary" and be jurisdictional under the final rule.
Similarly, a lake, pond, or impoundment of a jurisdictional water may be jurisdictional if it
contributes surface water flow to a traditional navigable water or territorial sea in a typical
year.

•	To determine whether a waterbody contributes surface water flow to a traditional navigable
water or territorial sea in a typical year, one may use, for example, USGS maps, state and
local maps, aerial photography, or other remote sensing information or models that have been
verified to be reliable to assess a feature's flow path.

•	For example, a tool that may be used to determine the contribution of surface water flow
downstream is a trace analysis in a Geographic Information System (GIS), which allows
users to select a point on a map and the flow path will be traced downstream along the stream

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network until the network ends. The USGS StreamStats incorporates such a tool called the
"Flow (Raindrop) Path," available at: https://streamstats.usgs.gov/ss/.

DETERMINING INUNDATION BY FLOODING

•	A lake, pond, or impoundment of a jurisdictional water may meet the definition of a "water
of the United States" if it is inundated by flooding from a jurisdictional water in a typical
year. A wetland that is inundated by flooding from a jurisdictional water in a typical year is
an "adjacent wetland" under the final rule.

•	To determine whether a waterbody is inundated by flooding during a typical year one may
use, for example, on-site visual observations and field-based indicators of recent inundation
(e.g., the presence of water marks, sediment and drift deposits, water-stained leaves, or algal
mats), or remote tools and datasets such as USGS stream gage records, recurrence intervals
of peak flows, wetland surface water level records, flood records, aerial photography and
satellite imagery, or inundation modeling techniques and tools (e.g., tools available from the
USGS Flood Inundation Mapping (FIM) program).

•	A site-specific modeling tool that may be used to evaluate inundation is the Hydrologic
Engineering Center's River Analysis System (HEC-RAS) software, which allows users to
perform two-dimensional hydraulic calculations for natural and constructed channels, and to
perform inundation mapping and create inundation depth and floodplain boundary datasets.
The HEC-RAS software is available at: https://www.hec.usace.army.mil/software/hec-ras/.

DETERMINING A DIRECT HYDROLOGIC SURFACE CONNECTION

•	A wetland that is physically separated from a jurisdictional water by an artificial dike,
barrier, or similar artificial structure may be determined to be adjacent and therefore a "water
of the United States" under the final rule so long as that structure allows for a direct
hydrologic surface connection between the wetland and the jurisdictional water in a typical
year (e.g., through a culvert, tide gate, pump, or similar artificial feature). An adjacent
wetland is jurisdictional in its entirety when a road or similar artificial structure divides the
wetland, as long as the structure allows for a direct hydrologic surface connection through or
over that structure in a typical year.

•	To determine whether a wetland is separated only by an artificial structure that allows for a
direct hydrologic surface connection in a typical year, such artificial features may be
identified through on-site observations or remotely using construction design plans,
permitting data, state and local information, or levee or drainage district information.

DETERMINING SURFACE FLOW AND SURFACE WATER CONNECTIONS IN A

"TYPICAL YEAR"

•	Under the final rule, determining the jurisdictional status of a waterbody is generally
informed by understanding the normal periodic range of precipitation and other climactic
variables for that waterbody (i.e., "typical year").

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Tools, methods, datasets, observations and other sources of information used to evaluate
surface flow and surface water connections should be interpreted in the context of a typical
year. This ensures that the hydrologic conditions being evaluated are representative of the
normal periodic range of conditions (e.g., seasonally, annually) for the waterbody of interest,
and that determinations are not based on conditions that are too wet or too dry, such as during
a period of drought or after an extreme flood event. When conditions are not "typical," for
example where a stream is dry during conditions of drought, the agencies will use the best
available sources of information to evaluate whether that stream would flow intermittently in
a typical year.

A variety of tools and datasets are available to ensure that the time period of evaluation is
neither too wet nor too dry. The agencies will generally use a web-based antecedent
precipitation tool (APT) developed by the Army Corps of Engineers that collects National
Oceanic and Atmospheric Administration (NOAA) precipitation data from nearby weather
stations and compares precipitation from the period of interest to the past 30 years of
precipitation. For example, the tool can be used to compare precipitation data from the most
recent summer to the range of precipitation from the past 30 summers. For more information
on the APT, see the agencies Fact Sheet on "Typical Year" for the final revised definition of
"Waters of the United States" Rule.

Other climactic factors like temperature or drought patterns may be considered along with
precipitation. For example, drought periods may be identified by examining trends in drought
indices, such as the Palmer Drought Severity Index (PDSI), which takes into account not
only precipitation but also temperature, which affects evapotranspiration, and soil moisture
conditions. Time-series plots of PDSI values by month or year are available from the
National Climatic Data Center (NCDC) at: https://www.ncdc.noaa.gov/temp-and-
precip/drought/historical-palmers/psi/201811 -201910.

One may need to consider whether the sources of information being evaluated are
representative of the "typical year." The Web-based Water-Budget Interactive Modeling
Program (WebWIMP) is one source for approximate dates of wet and dry seasons for any
terrestrial location based on average monthly precipitation and estimated evapotranspiration,
and is available at: http://climate.geog.udel.edu/~wimp/.

In certain parts of the country and during certain times of the year, melting snowpack may
have a more significant influence on flow and surface water connections than rainfall.

Sources of information on snowpack can be found using NOAA's National Snow Analyses
available at: https://www.nohrsc.noaa.gov/nsaA or using NRCS's Snow Telemetry
(SNOTEL) data and products, available at: https://www.wcc.nrcs.usda.gov/snow/.


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