This map shows all of Maryland's Tier II high quality stream segments and their associated catchment/watershed. MDE uses Maryland Biological Stream Survey (MBSS) data for designating streams as Tier II. Using all MBSS stations sampled within a stream reach (defined as a section of stream from confluence to confluence), an arithmetic mean of the benthic index of biotic integrity (IBI) and the fish IBI is calculated. Only if the means of both the benthic and fish IBIs are greater than or equal to 4.00 is a stream reach designated as Tier II. As such, Tier II streams represent the best streams in Maryland in terms of water quality, water chemistry, habitat, and biotic assemblages. Tier II stream segments can range in length generally terminating at confluences, impoundment outfalls, and tidal boundaries. However, in planning activities, one should consider the entire upstream watershed to a Tier II stream as any changes to this watershed can potentially have an effect on the water quality of the Tier II stream. It is worth noting that once a stream segment is designated as Tier II, this designation lasts in perpetuity regardless of changes in water quality or local landuse. This map was last updated in Feb 2025.To access the publicly maintained list of all Tier II waters and for further information regarding Maryland's High Quality Tier II Waters, please visit https://mde.maryland.gov/programs/water/tmdl/integrated303dreports/pages/index.aspx

The digital segmented network based on watershed boundaries, ERF1-2, includes enhancements to the U.S. Environmental Protection Agency's River Reach File 1 (RF1) (USEPA, 1996; DeWald and others, 1985) to support national and regional-scale surface water-quality modeling. Alexander and others (1999) developed ERF1, which assessed the hydrologic integrity of the digital reach traces and calculated the mean water time-of-travel in river reaches and reservoirs. ERF1-2 serves as the foundation for SPARROW (Spatially Referenced Regressions (of nutrient transport) On Watershed) modeling. Within the context of a Geographic Information System, SPARROW estimates the proportion of watersheds in the conterminous U.S. with outflow concentrations of several nutrients, including total nitrogen and total phosphorus, (Smith, R.A., Schwarz, G.E., and Alexander, R.B., 1997). This version of the network expands on ERF1 (version 1.2; Alexander et al. 1999), and includes the incremental and total drainage area derived from 1-kilometer (km) elevation data for North America. Previous estimates of the water time-of-travel were recomputed for reaches with water- quality monitoring sites that included two reaches. The mean flow and velocity estimates for these split reaches are based on previous estimation methods (Alexander et al., 1999) and are unchanged in ERF1-2. Drainage area calculations provide data used to estimate the contribution of a given nutrient to the outflow. Data estimates depend on the accuracy of node connectivity. Reaches split at water- quality or pesticide-monitoring sites indicate the source point for estimating the contribution and transport of nutrients and their loads throughout the watersheds. The ERF1-2 coverage extends the earlier ERF1 coverage by providing digital-elevation-model (DEM-based estimates of reach drainage area founded on the 1-kilometer data for North America (Verdin, 1996; Verdin and Jenson, 1996). A 1-kilometer raster grid of ERF1-2 projected to Lambert Azimuthal Equal Area, NAD 27 Datum (Snyder, 1987), was merged with the HYDRO1K flow direction data set (Verdin and Jenson, 1996) to generate a DEM-based watershed grid, ERF1_2WS. The watershed boundaries are maintained in a raster (grid cell) format as well as a vector (polygon) format for subsequent model analysis. Both the coverage, ERF1-2, and the grid, ERF1-2WS are available at: http://water.usgs.gov/lookup/gisgetlist. The version of RF1 used to compile ERF1-2 was an early edition of a USGS RF1 translation and was updated by USEPA (USEPA, 1996). The capabilities of the enhanced version of RF1 (ERF1-2) and the current USEPA version have not been evaluated. The user is referred to the USEPA version [http://www.epa.gov/owow/monitoring/rf/rfindex] for discussions of streamflow accuracy and general background on the origin of RF1.This is a MD iMAP hosted service layer. Find more information at https://imap.maryland.gov.Feature Service Layer Link:https://geodata.md.gov/imap/rest/services/Hydrology/MD_Waterbodies/FeatureServer/0

description: This is statewide digital watershed data. This file depicts the State with 138 separate watersheds each with an 8-digit numeric code. This file was created primarily for State and Federal agency use. The creation of this file goes back many years and involved several State and Federal agencies. This file was derived from a more detailed watershed file (Maryland's Third-Order Watershed). The U.S. Natural Resources Conservation Service (NRCS) redefined the third order watersheds creating the HUA14 file. The process used to create this file is consistent with the elevation contour information found on the US Geological Survey's 7.5 minute topographic quadrangle maps and the Maryland Department of the Environment's watershed location and naming conventions. This file is similar, but not identical, to the US Natural Resources Conservation Service's (NRCS) Hydrologic Unit Code (HUC11) watershed file. 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 watershed drainage areas were defined for streams less than third order and some large area Watersheds were split to maintain a maximum size of 15,000 acres. This watershed data is used by many state and local government agencies to accurately locate and report many landscape activities by watershed in Maryland.; abstract: This is statewide digital watershed data. This file depicts the State with 138 separate watersheds each with an 8-digit numeric code. This file was created primarily for State and Federal agency use. The creation of this file goes back many years and involved several State and Federal agencies. This file was derived from a more detailed watershed file (Maryland's Third-Order Watershed). The U.S. Natural Resources Conservation Service (NRCS) redefined the third order watersheds creating the HUA14 file. The process used to create this file is consistent with the elevation contour information found on the US Geological Survey's 7.5 minute topographic quadrangle maps and the Maryland Department of the Environment's watershed location and naming conventions. This file is similar, but not identical, to the US Natural Resources Conservation Service's (NRCS) Hydrologic Unit Code (HUC11) watershed file. 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 watershed drainage areas were defined for streams less than third order and some large area Watersheds were split to maintain a maximum size of 15,000 acres. This watershed data is used by many state and local government agencies to accurately locate and report many landscape activities by watershed in Maryland.

This dataset consists of a digital geospatial representation of all identified Tier II segments in the State of Maryland. Based on data collected between 1995-2019, this dataset currently contains information for 263 designated Tier II stream segments. Main segment breakpoints were determined using the 100,000:1 National Hydrography Dataset (NHD). The final designated Tier II segments are the merged sub segments that make up the 24,000:1 NHD meeting the 100,000:1 breakpoints. Tier II stream segments generally terminate at confluences, impoundment outfalls, and tidal boundaries.Creator: Maryland Department of the Environment, Water Science Administration (MDE WSA) Assessment Data: Maryland Department of Natural Resources, Monitoring and Non-tidal Assessment Division, Maryland Biological Stream Survey Program (DNR MBSS), MDE WSA, Baltimore County Department of Environmental Protection and Sustainability, Frederick County Department of Sustainability and Environmental Resources, Wetland Studies and Solutions, McCormick Taylor Inc., and various non-government certified entities. Other Geospatial Data: USGSMap Service Link: https://mdewin64.mde.state.md.us/arcgis/rest/services/MDE_Water_Quality/MD_TierIIHighQualityWaters_2022/MapServer/1

This dataset represents the final version of Tier II catchments used for assimilative capacity determination, or watersheds located within the State of Maryland. Oftentimes multiple designated Tier II streams (with their own individual watersheds) occur within a common, larger watershed. Supercatchments are those watersheds whose surface areas drain to the most downstream Tier II stream segment in a collective watershed area. Based on data collected between 1995-2019, this dataset currently contains information for 195 Tier II catchments.Map Service Link:https://mdewin64.mde.state.md.us/arcgis/rest/services/MDE_Water_Quality/MD_TierIIHighQualityWaters_2021/MapServer/2

This set of maps displays every approved TMDL watershed, categorized by pollutant. Maps include nitrogen, phosphorus, and sediment; developed from both the State and the 2010 Chesapeake Bay TMDLs. Links to both TMDL programs and downloads are featured.Provided by the Maryland Department of the Environment (MDE)

This layer contains the boundaries and IDs of the Maryland tax maps produced by Maryland Department of Planning. Tax maps, also known as assessment maps, property maps or parcel maps, are a graphic representation of real property showing and defining individual property boundaries in relationship to contiguous real property.This is a MD iMAP hosted service layer. Find more information at https://imap.maryland.gov.Feature Service Layer Link:https://geodata.md.gov/imap/rest/services/PlanningCadastre/MD_PropertyData/MapServer/2

This is a MD iMAP hosted service layer. Find more information at http://imap.maryland.gov. This file (SWSUB8) is a statewide digital watershed file. It depicts the State with 138 separate watersheds each with an 8-digit numeric code. The file was created primarily for State and Federal agency use. The creation of this file goes back many years and involved several State and Federal agencies. This file was derived from a more detailed watershed file (Maryland's Third-Order Watershed). The process used to create this file is consistent with the elevation contour information found on the US Geological Survey's 7.5 minute topographic quadrangle maps and the Maryland Department of the Environment's watershed location and naming conventions. This file is similar - but not identical - to the US Natural Resources Conservation Service's (NRCS) Hydrologic Unit Code (HUC11) watershed file. 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 watershed drainage areas were defined for streams less than third order and some large area Watersheds were split to maintain a maximum size of 15 - 000 acres. Feature Service Layer Link: http://geodata.md.gov/imap/rest/services/Hydrology/MD_Watersheds/FeatureServer/1 ADDITIONAL LICENSE TERMS: The Spatial Data and the information therein (collectively "the Data") is provided "as is" without warranty of any kind either expressed implied or statutory. The user assumes the entire risk as to quality and performance of the Data. No guarantee of accuracy is granted nor is any responsibility for reliance thereon assumed. In no event shall the State of Maryland be liable for direct indirect incidental consequential or special damages of any kind. The State of Maryland does not accept liability for any damages or misrepresentation caused by inaccuracies in the Data or as a result to changes to the Data nor is there responsibility assumed to maintain the Data in any manner or form. The Data can be freely distributed as long as the metadata entry is not modified or deleted. Any data derived from the Data must acknowledge the State of Maryland in the metadata.

Under contract with the State of Maryland’s Department of Natural Resources (MDNR),Versar provides support to the Maryland Biological Stream Survey (MBSS) - a comprehensive survey to assess the status of biological resources in Maryland’s non-tidal streams, identify stresses and impacts, and establish a means to monitor the condition of the streams. Round One of the MBSS (a three-year study, 1995 to 1997) was based on a stream network derived from a GIS data set at a 1:250,000 scale. Round Two of the project, conducted in 2000-2004, required a finer scale in the base stream network, and a refined sampling design focusing on Maryland's 8-digit watersheds. Stream data at a 1:100,000 scale were selected as an suitable base for the second round of the project.This is a MD iMAP hosted service. Find more information on https://imap.maryland.gov.Feature Service Link: https://geodata.md.gov/imap/rest/services/Hydrology/MD_StreamHealth/FeatureServer/2

This is a MD iMAP hosted service layer. Find more information at http://imap.maryland.gov. These data map hub and corridor elements within the green infrastructure. The Green Infrastructure Assessment was developed to provide decision support for Maryland's Department of Natural Resources land conservation programs. Methods used to identify and rank green infrastructure lands are intended soley for this use. Other applications are at the discretion of the user. The Maryland Department of Natural Resources is not responsible for any inaccuracies in the data and does not necessarily endorse any uses or products derived from the data other than those for which the data were originally intended. Maryland's green infrastructure is a network of undeveloped lands that provide the bulk of the state's natural support system. Ecosystem services - such as cleaning the air - filtering water - storing and cycling nutrients - conserving soils - regulating climate - and maintaining hydrologic function - are all provided by the existing expanses of forests - wetlands - and other natural lands. These ecologically valuable lands also provide marketable goods and services - like forest products - fish and wildlife - and recreation. The Green Infrastructure serves as vital habitat for wild species and contributes in many ways to the health and quality of life for Maryland residents. To identify and prioritize Maryland's green infrastructure - we developed a tool called the Green Infrastructure Assessment (GIA). The GIA was based on principles of landscape ecology and conservation biology - and provides a consistent approach to evaluating land conservation and restoration efforts in Maryland. It specifically attempts to recognize: a variety of natural resource values (as opposed to a single species of wildlife - for example) - how a given place fits into a larger system - the ecological importance of natural open space in rural and developed areas - the importance of coordinating local - state and even interstate planning - and the need for a regional or landscape-level view for wildlife conservation. The GIA identified two types of important resource lands - hubs"" and ""corridors."" Hubs typically large contiguous areas - separated by major roads and/or human land uses - that contain one or more of the following: Large blocks of contiguous interior forest (containing at least 250 acres - plus a transition zone of 300 feet) Large wetland complexes - with at least 250 acres of unmodified wetlands; Important animal and plant habitats of at least 100 acres - including rare - threatened - and endangered species locations - unique ecological communities - and migratory bird habitats; relatively pristine stream and river segments (which - when considered with adjacent forests and wetlands - are at least 100 acres) that support trout - mussels - and other sensitive aquatic organisms; and existing protected natural resource lands which contain one or more of the above (for example - state parks and forests - National Wildlife Refuges - locally owned reservoir properties - major stream valley parks - and Nature Conservancy preserves). In the GIA model - the above features were identified from Geographic Information Systems (GIS) spatial data that covered the entire state. Developed areas and major roads were excluded - areas less than 100 contiguous acres were dropped - adjacent forest and wetland were added to the remaining hubs - and the edges were smoothed. The average size of all hubs in the state is approximately 2200 acres. Corridors are linear features connecting hubs together to help animals and plant propagules to move between hubs. Corridors were identified using many sets of data - including land cover - roads - streams - slope - flood plains - aquatic resource data - and fish blockages. Generally speaking - corridors connect hubs of similar type (hubs containing forests are connected to one ano

This Image Service of Maryland Property Data allows for the manipulation of the display properties of the Statewide Tax Maps dataset. This is a MD iMAP hosted service. Find more information at https://imap.maryland.gov.Image Service Link: https://geodata.md.gov/imap/rest/services/PlanningCadastre/MD_PropertyData/ImageServer

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.The Department of Natural Resources makes no warranty, expressed or implied, as to the use or appropriateness of Spatial Data, and there are no warranties of merchantability or fitness for a particular purpose or use. The information contained in Spatial Data is from publicly available sources, but no representation is made as to the accuracy or completeness of Spatial Data. The Department of Natural Resources shall not be subject to liability for human error, error due to software conversion, defect, or failure of machines, or any material used in the connection with the machines, including tapes, disks, CD-ROMs or DVD-ROMs and energy. The Department of Natural Resources shall not be liable for any lost profits, consequential damages, or claims against the Department of Natural Resources by third parties. The liability of the Department of Natural Resources for damage regardless of the form of the action shall not exceed any distribution fees that may have been paid in obtaining Spatial Data.This is a MD iMAP hosted service layer. Find more information at https://imap.maryland.gov.Feature Service Layer Link:https://geodata.md.gov/imap/rest/services/Hydrology/MD_Watersheds/FeatureServer/2

This point dataset represents baseline Tier II MBSS stations used to designate each high quality Tier II stream segment within the State of Maryland. Each point represents either one benthic macroinvertebrate station location or one fish station location. This dataset currently contains 412 points, based on data collected between 1995 – 2015.Map Service Link: https://mdewin64.mde.state.md.us/arcgis/rest/services/MDE_Water_Quality/MD_TierIIHighQualityWaters_2016/MapServer/0

Esri ArcGIS Online (AGOL) Map Image Layer which provides access to the MDOT SHA Recorded Plats data product.MDOT SHA Recorded Plats consists of polygon geometric features which represent the boundary of georeferenced MDOT SHA right of way plats throughout the State of Maryland. All plats included are recorded, that is to say they are recorded in land records as legal instruments. Each plat has a link to a scanned image on the Maryland State Archives (MSA) website (https://plats.net). This boundary data is owned by the MDOT SHA OHD Plats & Surveys Division (PSD). This information is for general informational purposes only and should be confirmed by MDOT SHA PSD to be deemed official.This data is updated nightly through an automated process which pulls data from several sources to create the plat bounding boxes. The process of georeferencing MDOT SHA right of way plats is ongoing. The plats in this data only represent plats that have been georeferenced. The sources include:PSD data for the location (corners) of platsORE data for information about platsThere are three criteria for a plat to be included in this data:The recorded date must be populatedThe plat corner coordinates must be entered by PSDThe plat URL must be populated by PSDFor more information, contact MDOT SHA OIT Enterprise Information Services:Email: GIS@mdot.maryland.gov

This layer is extracted from The High Resolution National Hydrography Dataset Plus (NHDPlus HR). This is an integrated set of geospatial data layers, including the best available National Hydrography Dataset (NHD), the 10-meter 3D Elevation Program Digital Elevation Model (3DEP DEM), and the National Watershed Boundary Dataset (WBD). The NHDPlus HR combines the NHD, 3DEP DEMs, and WBD to create a stream network with linear referencing, feature naming, "value added attributes" (VAAs), elevation-derived catchments, and other features for hydrologic data analysis.This is a MD iMAP hosted service layer. Find more information at https://imap.maryland.gov.Map Service Layer Link:https://geodata.md.gov/imap/rest/services/Agriculture/MD_NutrientManagementSetbacksFromWaterways/MapServer/0

Geographic Extent: SANDY_Restoration_DE_MD_QL2 Area of Interest covers approximately 3.096 square miles. Lot #5 contains the full project area Dataset Description: The SANDY_Restoration_DE_MD_QL2 project called for the Planning, Acquisition, processing and derivative products of LIDAR data to be collected at a nominal pulse spacing (NPS) of 0.7 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LIDAR Specification, Version 1. The data was developed based on a horizontal projection/datum of State Plane Zone Maryland (1900), NAD83, feet and vertical datum of NAVD1988 (GEOID12A), feet. LiDAR data was delivered in RAW flight line swath format, processed to create Classified LAS 1.2 Files formatted to 3842 individual 1500m x 1500m tiles, and corresponding Intensity Images and Bare Earth DEMs tiled to the same 1500m x 1500m schema, and Breaklines in ESRI shapefile format. Ground Conditions: LiDAR was collected in Winter 2013 / Spring 2014, while no snow was on the ground and rivers were at or below normal levels. In order to post process the LiDAR data to meet task order specifications, Quantum Spatial established a total of 78 QA control points and 99 Land Cover control points that were used to calibrate the LIDAR to known ground locations established throughout the SANDY_Restoration_DE_MD_QL2 project area.This is a MD iMAP hosted service. Find more information at https://imap.maryland.gov.Image Service Link: https://lidar.geodata.md.gov/imap/rest/services/Caroline/MD_caroline_aspect_m/ImageServer

This tool provides information on public water access in Maryland. Sites include boat ramps, soft launches, and transient docking facilities. Detailed information is organized by jurisdiction.Provided by the Maryland Department of Natural Resources (DNR)

This dataset represents the ‘nested’ Tier II catchments, or watersheds located within the State of Maryland. Oftentimes multiple designated Tier II streams (with their own individual watersheds) occur within a common, larger watershed. Nested catchments are those watersheds whose surface areas drain to the most downstream Tier II stream segment in a collective watershed area. Based on data collected between 1995-2019, this dataset currently contains information for 165 Tier II catchments.Creator: Maryland Department of the Environment, Water Science Administration (MDE WSA) Assessment Data: Maryland Department of Natural Resources, Monitoring and Non-tidal Assessment Division, Maryland Biological Stream Survey Program (DNR MBSS), MDE WSA, Baltimore County Department of Environmental Protection and Sustainability, Frederick County Department of Sustainability and Environmental Resources, Wetland Studies and Solutions, McCormick Taylor Inc., and various non-government certified entities. Other Geospatial Data: USGSMap Service Link: https://mdewin64.mde.state.md.us/arcgis/rest/services/MDE_Water_Quality/MD_TierIIHighQualityWaters_2022/MapServer/2

This data set represents the extent, approximate location and type of wetlands and deepwater habitats in the conterminous United States. These 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.This is a MD iMAP hosted service layer. Find more information at https://imap.maryland.gov.Feature Service Layer Link:https://geodata.md.gov/imap/rest/services/Hydrology/MD_Wetlands/MapServer/2

A subset of property listings from the Maryland Department of Transportation's Office of Real Estate and Economic Development office. These properties represent Transit-Oriented Development opportunities that are either currently open or are under development. This map is updated when new TOD opportunities arise or when status for TOD areas change. Use the interactive pop-up menus within the map for each property to view more information about the selected properties and to view the property in different maps and contexts. The state of Maryland is able to sell state-owned land periodically. This can involve public auctions as well. Please visit the Maryland Department of Transportation's Real Estate and Economic Development website for additional information: https://mdotrealestate.maryland.gov/Pages/default.aspx