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Downloadable from: http://dnrweb.dnr.state.md.us/gis/data/data.asp

Chesapeake Bay Commission Critical Area (CBCCA)

In 1984, the General Assembly enacted the Chesapeake Bay Critical Area Act to regulate development, manage land use and conserve natural resources on land in those areas designated as Critical Area. For this document, the Critical Area is all land and water areas within 1000 feet of the tidal waters' edge or from the landward edge of adjacent tidal wetlands and the lands under them. Georeferenced digital data files of the critical Area have been produced for Baltimore City and the 16 Maryland counties with land located within the Critical Area. The digital maps produced for each jurisdiction are polygons depicting the Critical Area and the land use classifications recognized by the Chesapeake Bay Critical Area Commission (CBCAC). Each jurisdiction is a separate file. The data were produced from hard copy parcel maps originally submitted by the counties as part of the requirements for developing their Critical Area Program.

DNR wetlands

These digital data files are records of wetlands location and classification as defined by the U.S. Fish & Wildlife Service's National Wetlands Inventory (NWI) program. See the Entity_and_Attribute_Information section for a detailed description of NWI's Classification scheme. These wetlands were mapped by Maryland Department of Natural Resources (MD DNR) using Maryland's Digital Orthophoto Quarter Quads. Data are available in 3.75 minute by 3.75 minute blocks and contain wetlands point, line, and area features and attributes. The wetlands were photo interpreted from the photography flown for the Digital Orthophoto Quarter Quads. These were flown over a period from 1988 to 1995. See supplemental information for additional details.

Forest Interior Dwelling Species (FIDS)

Potential habitat layer for Forest Interior Dwelling Species in the State of Maryland. These data are only the results of a model depicting where FIDS habitat might occur based on certain criteria. These polygons have NOT been field tested or field verified for actual FIDS presence.

Green Infrastructure – Hubs and Corridors

A network of natural areas identified by Department of Natural Resources that are ecologically significant on a statewide or regional scale.  Examples include: Large blocks of forest or wetlands, habitat for sensitive species and protected conservation areas.  Areas are grouped into hubs and corridors.

Greenprint—Targeted Ecological Areas (TEA)

A limited number of areas that rank exceptionally high for ecological criteria and that have a practical potential for preservation. The first step was to create an ecological baseline composed of several ecological datasets.
The first component is the original Green Infrastructure Assessment (1995 – 2000) which identifies large, contiguous blocks of significant forests and wetlands that contain Maryland’s most ecologically important remaining lands.  The Green Infrastructure’s hub and corridor network of habitat allows plant and animal migration, reduces forest fragmentation if protected, and provides important ecosystem services, such as biodiversity, cleaning air and water, storing nutrients, and protecting areas against storm and flood damage.

The rare species habitat component identifies areas where biodiversity conservation is needed to protect and restore Maryland's rare, threatened and endangered species, declining wildlife of greatest conservation need, and the key habitats and natural communities required to support them.

The aquatic life hotspots component identifies a network of lands leading to aquatic areas where conservation is needed to protect and restore areas of high aquatic biodiversity. Freshwater hotspots have been identified, and estuarine and marine areas will be identified.

The water quality protection component identifies sensitive lands such as forests, wetlands, and steep slopes where preservation is important for water quality.
From the ecological baseline, areas that scored in the top 10 percent for each of the components were merged to create the Targeted Ecological Areas.

Non-tidal Wetlands of Special State Concern (WSSC)

In Maryland certain wetlands with rare, threatened, endangered species or unique habitat receive special attention. The Code of Maryland Regulations (COMAR) Title 26, Subtitle 23, Chapter 06, Sections 01 & 02 identifies these Wetlands of Special State Concern (WSSC) and affords them certain protections including a 100 foot buffer from development. The Maryland Department of the Environment is responsible for identifying and regulating these wetlands. In general, the US Fish and Wildlife Service's National Wetlands Inventory wetlands provide the basis for identifying these special wetlands. Additional information, determined from field inspections, is used to identify and classify these areas.

NWI wetlands

This data set represents the extent, approximate location and type of wetlands and deep water habitats in the conterminous United States.  There data delineate the areal extent of wetlands and surface waters as defined by Cowardin et al. (1979).

Certain wetland habitats are excluded from the National mapping program because of the limitations of aerial imagery as the primary data source used to detect wetlands.  These habitats include seagrasses or submerged aquatic vegetation that are found in the intertidal and subtidal zones of estuaries and near shore coastal waters.  Some deepwater reef communities (coral or tuberficid worm reefs) have also been excluded from the inventory.  These habitats, because of their depth, go undetected by aerial imagery.
By policy, the Service also excludes certain types of “farmed wetlands” as may be defined by the Food Security Act or that do not coincide with the Cowardin et al. definition.  Contact the service’s Regional Wetland Coordinator for additional information on what types of farmed wetlands are included on wetland maps.Floodplains - The Q3 Flood Data are derived from the Flood Insurance Rate Maps (FIRMs) published by the Federal Emergency Management Agency (FEMA). The file is georeferenced to the earth's surface using the geographic projection and the decimal degree coordinate system.  The specifications for the horizontal control of Q3 Flood Data files are consistent with those required for mapping at a scale of 1:24000.  This metadata makes a reference to ""Q3 Flood Data Specifications.""  This is available from FEMA at ftp://ftp.fema.gov/mscdata/q3spec.txt

Protected Lands

This data set is a complete digital hydrologic unit boundary layer to the Subwatershed (12-digit) 6th level for US EPA Region 3 and the extent of the Chesapeake Bay Watershed. These hydrologic units included in this data set extend out to encompass the full 8-digit (4th order) sub-basin boundaries that in any way intersect US EPA Region 3 and fully contains any subwatershed boundaries that are contained within the Chesapeake Bay Watershed. This data set consists of geo-referenced digital data and associated attributes created in accordance with the "FGDC Proposal, Version 1.0 - Federal Standards For Delineation of Hydrologic Unit Boundaries 3/01/02 (http://www.ftw.nrcs.usda.gov/huc_data.html). Polygons are attributed with hydrologic unit codes for 4th level sub-basins, 5th level watersheds, 6th level subwatersheds, name, size, downstream hydrologic unit, type of watershed, non-contributing areas and flow modification. Arcs are attributed with the highest hydrologic unit code for each watershed, linesource and a metadata reference file.

Sensitive Species Project Review Area (SSPRA)

The statewide vector file shows buffered areas that primarily contain habitat for rare, threatened, and endangered species and rare natural community types. It was created over USGS 7.5 minute topographic quadrangle maps and it generally includes, but does not specifically delineate, such regulated areas as Natural Heritage Areas, Wetlands of Special State Concern, Colonial Waterbird Colonies, and Habitat Protection Areas. Version 1 also included Waterfowl Concentration and Staging Areas, but these areas have not been included in subsequent versions. The file is best displayed by the "Group" attribute.

Downloadable from http://nhd.usgs.gov/ , http://viewer.nationalmap.gov/viewer/

National Hydrography Dataset

Streams - The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that comprise the nation's surface water drainage system. Medium resolution NHD is based on the content of the U.S. Geological Survey 1:100,000-scale Digital Line Graph (DLG) hydrography data, integrated with reach-related information from the U.S. Environmental Protection Agency Reach File Version 3.0 (RF3). More specifically, it contains reach codes for networked features and isolated lakes, flow direction, names, stream level, and centerline representations for areal water bodies. Reaches are also defined to represent water bodies and the approximate shorelines of the Great Lakes, the Atlantic and Pacific Oceans and the Gulf of Mexico. The NHD also incorporates the National Spatial Data Infrastructure framework criteria established by the Federal Geographic Data Committee.

National Hydrography Dataset—Waterbodies

This is a spatial data layer of water body polygons from the NHD. The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that comprise the nation's surface water drainage system. Medium resolution NHD is based on the content of the U.S. Geological Survey 1:100,000-scale Digital Line Graph (DLG) hydrography data, integrated with reach-related information from the U.S. Environmental Protection Agency Reach File Version 3.0 (RF3). More specifically, it contains reach codes for networked features and isolated lakes, flow direction, names, stream level, and centerline representations for areal water bodies. Reaches are also defined to represent water bodies and the approximate shorelines of the Great Lakes, the Atlantic and Pacific Oceans and the Gulf of Mexico. The NHD also incorporates the National Spatial Data Infrastructure framework criteria established by the Federal Geographic Data Committee.

Downloadable from http://planning.maryland.gov/ourproducts/pfamap.shtml

Priority Funding Areas (PFA)

The 1997 Smart Growth Areas Act established certain areas as Priority Funding Areas determining the locations most suitable for State-funded projects.  These areas are: municipalities, Baltimore City, areas inside the Baltimore and Washington Beltways, Revitalization Areas designated by the Maryland Department of Housing and Community Development (DHCD), Enterprise Zones, and Heritage Areas.  This legislation allows Counties to designate additional areas as Priority Funding Areas if they meet specified requirements for use, water and sewer service, and residential density.  Counties must provide maps and other information which show the precise location of their Priority Funding Areas based on criteria in the legislation.  The Maryland Office of Planning is responsible for providing State agencies with maps that illustrate the Priority Funding Areas along with any comments by the Office of Planning on locally designated areas. Areas eligible for county designation are:
      - Areas with industrial zoning;
      - Areas with employment as the principal use, which are provide with, or planned for, sewer service;
      - Residential areas which have an average density of 2 or more units per acre, are within designated growth areas, and are served by water or sewer systems, or
      - Rural Villages designated in the comprehensive plan before July 1, 1998.

Other areas within county-designated growth areas that:
      - Reflect a long-term policy for promoting an orderly expansion of growth and an efficient use of land and public services;
      - Are planned to be served by water and sewer systems, and
      - Have a permitted density of 3.5 or more units per acre for new residential development.

Downloadable from http://soildatamart.nrcs.usda.gov/


This data set is a digital soil survey and generally is the most detailed level of soil geographic data developed by the National Cooperative Soil Survey. The information was prepared by digitizing maps, by compiling information onto a planimetric correct base and digitizing, or by revising digitized maps using remotely sensed and other information.
This data set consists of georeferenced digital map data and computerized attribute data. The map data are in a soil survey area extent format and include a detailed, field verified inventory of soils and miscellaneous areas that normally occur in a repeatable pattern on the landscape and that can be cartographically shown at the scale mapped. A special soil features layer (point and line features) is optional. This layer displays the location of features too small to delineate at the mapping scale, but they are large enough and contrasting enough to significantly influence use and management. The soil map units are linked to attributes in the National Soil Information System relational database, which gives the proportionate extent of the component soils and their properties.

303d Listed Streams

US EPA Region 3 (District of Columbia, Delaware, Maryland, Pennsylvania, Virginia, West Virginia)river segments, lakes, and estuaries designated under Section 303(d) of the Clean Water Act. Each State will establish Total Maximum Daily Loads (TMDLs) for these waters. 303(d) Waterbodies are coded onto route.rch (Transport and Coastline Reach) feature of NHD to create Linear and Point Events.Point events are attached to a reach in NHD to represent a TMDL for many reasons: to represent an estuary, to represent a shellfish area (if state preferred to represent the TMDL in this manner) - refer to NOAA's shellfish areas for a more accurate representation (http://state-of-coast.noaa.gov/bulletins/html/sgw_04/sgw.html). Point events represent point source dischargers, or, if there is no reach in NHD, they are used to represent the TMDL.303(d) Waterbodies are coded onto NHD Waterbody reaches (region.rch) to create Waterbody Shapefiles.  In addition to NHD reach indexed data there may also be custom shapefiles (point, line, or polygon) that are not associated with NHD and are in an EPA standard format that is compatible with EPA's Reach Address Database.  These custom shapefiles are used to represent locations of 303(d) waterbodies that are not represented well in NHD.

Downloadable from
MDE's High Quality Waters Site

Tier II Waters – any waters listed as Tier II, pristine waters

The Clean Water Act requires three components to water quality standards that set goals for and protect each States/ waters.  The three components are: (1) designated uses that set goals for each water body (e.g., recreational use), (2) criteria that set the minimum conditions to support the use (e.g., bacterial concentrations below certain concentrations) and (3) an antidegradation policy that maintains high quality waters so they are not allowed to degrade to meet only the minimum standards.  The designated uses and criteria set the minimum standards for Tier I.

Maryland’s antidegradation policy has been promulgated in three regulations: COMAR sets out the policy itself, COMAR, which is discussed here, provides the implementation of Tier II (high quality waters) of the antidegradation policy, and COMAR that describes Tier III (Outstanding National Resource Waters or ONRW), the highest quality waters.  No Tier III waters have been designated at this time.

Tier II antidegradation implementation has the greatest immediate effect on local government planning functions so MDE has prepared this set of Tier II GIS data layers to provide technical assistance to local governments working to complete the Water Resources Element of their comprehensive plans as required by HB 1141.  As poart of this process, MDE has created a catchment dataset representing the general land area that can affect that Tier II stream’s segment water quality via run off.
The publicly maintatined list of all Tier II waters and for further information regarding Maryland’s High Quality Waters, Tier II, please visit here

Data from MD DNR

Biological Restoration Initiative Watersheds (BRI)

Most of the biological impairments on Maryland’s 303(d) list are due to the degradation of small, fairly shallow, free-flowing streams. MDE has initiated a Biological Restoration Initiative (BRI) to target resources to streams with the greatest recovery potential.  This restoration initiative, a part of Maryland’s 319 Nonpoint Source Program, is coordinated with Maryland’s Chesapeake and Atlantic Bays Trust Fund through the Fund’s system of targeting resources [PDF].
Maryland’s Biological Restoration Initiative works in concert with the State’s anti-degradation policy implementation designed to protect high quality streams. These streams are identified using the Department of Natural Resources Maryland Biological Stream Survey (MBSS) Program data. These high quality streams receive additional scrutiny to ensure that their biological integrity is protected. 

Biological restoration of streams is also conducted via agricultural conservation programs; local government programs, including the federal NPDES Stormwater permit program administered by MDE; and various other State and federal initiatives.

Blue Infrastructure (BI)

A subset of watersheds created for the Blue Infrastructure Project (BI) based on the DNR 12 digit watersheds as follows; this file (SWSHED12) is a statewide digital watershed file. It was created primarily for state and federal agency use. The watersheds define Strahler (Strahler 1952 p. 1120) third order stream drainage by contours on U.S. Geological Survey (USGS) 7.5 minute quadrangle map sheets. Some watersheds drainage areas were defined for streams less than third order and some large area watershed were split to maintain a maximum size of 15,000 acres. The watershed boundaries in this file were developed in a joint state and federal effort to create a consistent watershed file for use by all government agencies with an interest in Maryland's watersheds. The U.S. Natural Resources Conservation Service (NRCS) redefined the third order watersheds creating the HUA14 file. This file contains all of the HUA14 watersheds and some added watersheds to maintain water quality sampling sites. It was also used to create the Maryland Sub-Watershed file.

Stronghold Watersheds

In its 17 years of assessing the health of Maryland’s streams, the Maryland Biological Stream Survey has identified those watersheds around the State that are most important for the protection of Maryland’s aquatic biodiversity. Known as Maryland’s “Stronghold Watersheds”, these locations are the places where rare, threatened, or endangered species of fish, amphibians, reptiles, or mussels have the highest numbers.

Most of these species used to have greater abundance and distribution throughout the State, but now are holding out in these limited areas. Generally, these species are the most sensitive to environmental degradation. A small change in watershed or stream health can permanently eliminate one or more of these sensitive species. As a result, maintaining the health of these watersheds is of critical importance if we are to sustain these species and the vital ecosystem services they provide.

Data from Other Sources

Impervious Surfaces

Refers to all hard surfaces like paved roads, parking lots, roofs, and even highly compacted soils like sports fields.

Land Use/Land Cover

MDP publishes statewide land use/land cover data based on analysis of parcel information in conjunction with high altitude aerial photography and satellite imagery.  This Land Use dataset utilizes the Anderson Level 2 Classification System to display various types of Land Use characteristics and types of Land Cover for each County in the State of Maryland and also includes Baltimore City. This is a draft version of the 2008 dataset released by MDP.

Trust Fund Watersheds

Watersheds with “trust funds” set aside for their protection/restoration/care.


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