Description: 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 within the Code of Maryland Regulations (COMAR): COMAR 26.08.02.04 sets out the policy itself, COMAR 26.08.02.04-1, which is discussed here, provides for implementation of Tier II (high quality waters) of the antidegradation policy, and COMAR 26.08.02.04-2 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 the Maryland Department of the Environment (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 part of this process, MDE has created this dataset representing the official record of all Maryland Tier II (high quality) stream segments as determined by MDE, the regulatory agency responsible for identification and listing of Maryland's Tier II waters. This dataset consists of a digital geospatial representation of all identified Tier II segments which includes those stream segments promulgated in (COMAR) 26.08.02.04-1, and those additional segments proposed during the current Triennial Review of Maryland Regulations, known as the pending list. Pending segments are Tier II segments awaiting promulgation. This is a vector line file that was developed using the 24,000:1 scale National Hydrography Dataset (NHD) coverage for Maryland, and each identified Tier II stream segment has been linked to the NHD using the unique common identifier (COMID) code. 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. The publicly maintained list of all Tier II waters and for further information regarding Maryland's High Quality Waters, Tier II, please visit http://mde.maryland.gov/programs/Water/TMDL/Integrated303dReports/Pages/Antidegradation.aspxAcknowledgement of the Maryland Department of the Environment, Science Services Administration as a data source would be appreciated in products developed from these data, and such acknowledgement as is standard for citation and legal practices for data sources is expected by users of this data. Sharing new data layers developed directly from these data would also be appreciated by Maryland Department of the Environment Science Services Administration staff. MDE shall not be held liable for improper or incorrect use of this data. These data are not legal documents and are not to be used as such.
Copyright Text: MD iMAP, MDE, The Maryland Department of the Environment Science Services Administration would like to acknowledge the Maryland Department of Natural Resources' MANTA Division, Maryland Biological Stream Survey Program for providing biological stream data as well as the associated geospatial information. MDE would also like to acknowledge the USGS for their 24,000:1 scale National Hydrography Dataset which was used during the development of this line file.
Description: 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 26.08.02.04 sets out the policy itself, COMAR 26.08.02.04-1, which is discussed here, provides for implementation of Tier II (high quality waters) of the antidegradation policy, and COMAR 26.08.02.04-2 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 part of this process, MDE has created a catchment dataset representing the general land area that can directly affect that Tier II stream's segment water quality via run off. The publicly maintained list of all Tier II waters and for further information regarding Maryland's High Quality Waters, Tier II, please visit http://www.mde.state.md.us/ResearchCenter/Data/waterQualityStandards/Antidegradation/index.aspAcknowledgement of the Maryland Department of the Environment as a data source would be appreciated in products developed from these data, and such acknowledgement as is standard for citation and legal practices for data source is expected by users of this data. Sharing new data layers developed dierctly from these data would also be appreciated by the Maryland Department of the Environment staff. Users should be aware that comparision with other data sets for the same area may be inaccurate due to inconsistencies resulting from changes in mapping conventions, data collection, and computer processes over time. The data set is not a survey document and should not be utilized as such. Data used in the creation of this tool was from many sources are not perfect. The distributor shall not be liable for imporper or incorrect use of this data, based on the description of appropriate/inappropriate uses described in this metadata document. These data are not legal documents and are not to be used as such. Final identification of Tier II waters shall be made based on consulting the regulation COMAR 26.08.02.04-1 and the list of promulgated and pending waters maintained at the website: http://www.mde.state.md.us/ResearchCenter/Data/waterQualityStandards/Antidegradation/index.asp
Copyright Text: MD iMAP, MDE, The Maryland Department of the Environment Science Services Administration would like to acknowledge the Maryland Department of Natural Resources' MANTA Division, Maryland Biological Stream Survey Program for providing biological stream sampling station data as well as the associated geospatial information. MDE would also like to acknowledge the USGS for their 24,000:1 scale National Hydrography Dataset which was used during the development of this line file.