# COMAR Title 26 — Department of the Environment

## Subtitle 08 — Water Pollution

### Chapter 02 — Water Quality

#### Regulation .08 Stream Segment Designations and Existing Uses.

*COMAR 26.08.02.08*

A. General.

  (1) All geographic coordinates provided within this regulation are expressed in decimal degrees latitude and longitude using the North American Datum of 1983. In this regulation, Maryland's waters are organized by sub-basin. For most Class I, I-P, III, III-P, IV, or IV-P waters, the limits indicate the most downstream boundary point or line for the segment. In some cases, an upstream point and a downstream point are provided to describe those uses that may apply only to a limited segment of a water body. In tidal areas, the segments are defined by polygons defined by three or more points as numbered and expressed in narrative format in column four and defined by latitude and longitude point locations in columns two and three. Any waterbody not specifically listed in the table is a Class I water.

  (2) Tidal Segmentation Rationale. Water quality standards for the Chesapeake Bay and its tidal tributaries will be assessed on a “Bay Segment” scale. The segmentation is based on decisions made by the Chesapeake Bay Program in 1998 and 2003, and documented in Chesapeake Bay Program Analytical Segmentation Scheme Revisions, Decisions, and Rationales: 1983-2003 (EPA 903-R-04-008) as adjusted by the Chesapeake Bay Program after cussions with the affected State jurisdictions.

  (3) Tidal Segment Boundaries. When using latitude and longitude to delineate Chesapeake Bay tidal segments, the limits are narrative descriptions that delineate the base points of reference. Chesapeake Bay tidal segments generally follow the shoreline contour at mean low water, and include all major bays, creeks, and branches present within the narrative limits of a given segment. The origin of latitudes and longitudes used for the Chesapeake Bay and its tidal tributaries is NAD83.

  (4) Application of Chesapeake Bay Segmentation Scheme. The tidal boundaries set forth in this regulation are defined for water quality standards purposes within the Department only, and are not applicable to other agency regulations identified for other purposes.

  (5) No Grow Zones. Submerged Aquatic Vegetation (SAV) “No-Grow” Zones (NGZ) are present in some shallow water designated use segments. The SAV “No Grow Zones” are identified in Technical Support Document for Identification of Chesapeake Bay Designated Uses and Attainability-2004 Addendum (EPA 903-R-04-006), Figures V-1 to V-12, which is incorporated by reference. The no grow zones shall be excluded from the assessment of the shallow water designated use.

  (6) Existing Uses. Several of the sub-basins in this regulation contain stream segments that support existing uses that require different water quality than the designated use. These existing uses have been determined in accordance with Regulation .04-1 of this chapter. The existing uses for these stream segments are described both in terms of the existing uses supported (e.g., naturalized reproducing brown trout population) and the water quality currently known to sustain them. For determining effluent limits, closure periods, and other regulatory protection measures, these existing uses and the water quality necessary to maintain them must be protected consistent with Regulation .04-1 of this chapter. These existing uses are maintained and can be accessed on the Department’s website.

B. Sub-Basin 02-12-02: Lower Susquehanna River Area.

C. Sub-Basin 02-13-01: Coastal Area.

D. Sub-Basin 02-13-02: Pocomoke River Area.

E. Sub-Basin 02-13-03: Nanticoke River Area.

F. Sub-Basin 02-13-04: Choptank River Area.

G. Sub-Basin 02-13-05: Chester River Area.

H. Sub-Basin 02-13-06: Elk River Area.

I. Sub-Basin 02-13-07: Bush River Area.

J. Sub-Basin 02-13-08: Gunpowder River Area.

K. Sub-Basin 02-13-09: Patapsco River Area.

L. Sub-Basin 02-13-10: West Chesapeake Bay Area.

M. Sub-Basin 02-13-11: Patuxent River Area.

N. Sub-Basin 02-14-01: Lower Potomac River Area.

O. Sub-Basin 02-14-02: Washington Metropolitan Area.

P. Sub-Basin 02-14-03: Middle Potomac River Area.

Q. Sub-Basin 02-14-05: Upper Potomac River Area.

R. Sub-Basin 02-14-10: North Branch Potomac River Area.

S. Sub-Basin 05-02-02: Youghiogheny River Area.

T. Sub-Basin 02-05-03: Conewago Creek.

U. Sub-Basin 02-13-99: Chesapeake Bay (Mainstem).