PTRC began monitoring the tidal section of the River in 2003, spurred by concern over bacteria levels. We regularly sample the waters for water quality indicators.
Water Quality Standards and the Clean Water Act
The federal Clean Water Act sets an overarching environmental goal that all waters of the United States be “fishable” and “swimmable.” It requires states to establish appropriate uses for their waters and adopt water quality standards that are protective of those uses. The Clean Water Act also requires that every two years jurisdictions develop a list of waterways that are impaired by pollutants and do not meet water quality standards. For those waterways identified on the impaired list, a Total Maximum Daily Load (TMDL) must be developed. A TMDL is essentially a “pollution diet” that identifies the maximum amount of a pollutant the waterway can receive and still meet water quality standards.
Maryland has established water quality standards “to restore and maintain the chemical, physical and biological integrity of the Nation’s waters” as required by section 101 of the Clean Water Act. There are three major components of water quality standards – designated uses, water quality criteria, and antidegradation policies.
Maryland regulations assign each stream and other water body a “designated use.” The designated use for a water body answers the public’s question, “What do we want to use this water body for?” A water body’s designated use may or may not be supported now, but should be attainable.
In general, the Port Tobacco River watershed is divided into two designated use categories.
- Use I, Water Contact Recreation and Protection of Aquatic Life, covers areas upstream of the Port Tobacco Marina.
- Use II, Shellfish Harvesting Waters, covers the river from Windmill Point to the Port Tobacco Marina. This use includes:
- Migratory spawning and nursery use: February 1 to May 31, inclusive.
- Shallow water submerged aquatic vegetation use: April 1 to October 30, inclusive.
- Open water fish and shellfish use: January 1 to December 31, inclusive.
Water Quality Criteria
Water quality criteria are levels of individual pollutants or water quality characteristics that, if met, will protect the designated uses of the water. Maryland has established numerical criteria for bacteria, dissolved oxygen, temperature, pH, turbidity, color, and toxic substances that are specific to designated uses.
Maryland has established the following criteria for Class I Waters, Water Contact Recreation and Protection of Nontidal Warmwater Aquatic Life:
- Bacteria indicator criteria vary depending on frequency of use of the water body, ranging from 33/100 milliliters to 151/100 milliliters for enterococci, and from 126/100 milliliters to 576/100 milliliters for E. coli.
- The dissolved oxygen concentration may not be less than 5 milligrams/liter at any time.
- The maximum temperature outside the mixing zone may not exceed 90°F (32°C) or the ambient temperature of the surface waters, whichever is greater.
- Normal pH values may not be less than 6.5 or greater than 8.5.
- Turbidity may not exceed levels detrimental to aquatic life.
- Color in the surface water may not exceed 75 units as a monthly average, measured in Platinum Cobalt Units.
- Numerical criteria are established for specific toxic substances.
Criteria for Class II Waters, Support of Estuarine and Marine Aquatic Life and Shellfish Harvesting, are the same as for Class I Waters, except that in Shellfish Harvest waters there may not be any pathogenic or harmful organisms, such as fecal coliform, in sufficient quantities to constitute a public health hazard.
Maryland’s antidegradation policy assures that water quality continues to support designated uses. U.S. Environmental Protection Agency (EPA) regulations provide for three tiers of protection:
- Tier 1 specifies the minimum standard that must be met — support of balanced indigenous populations and support of contact recreation. This is often referred to as “fishable-swimmable.”
- Tier 2 protects water that is better than the minimum specified for that designated use.
- Tier 3 protects Outstanding National Resource Waters. Maryland is developing standards for this level of protection.
Jennie Run (shown above in green adjacent to Mitchell Road) and Hoghole Run (shown above in pink adjacent to Rose Hill Road) are designated as Tier 2 waters.
Amendments to county plans that result in a new discharge to Tier 2 waters require an antidegradation review. The antidegradation review must consider the following:
- Can the discharge be avoided or placed elsewhere? If so, that should be done.
- If the discharge is necessary, has everything been done to minimize that water quality impact? If the impact has been minimized to the greatest extent feasible, but an impact to water quality will still occur, a social and economic justification (SEJ) for that impact must be prepared and approved by the Maryland Department of the Environment before the discharge can be permitted. The SEJ must demonstrate that alternatives are not economically feasible and are consistent with Smart Growth.
- Public input. The SEJ must undergo a public process similar to that for all permits and the SEJ is thus open for public review.
If a state concludes that a water body fails to meet one or more of its water quality standards, section 303(d) of the Clean Water Act requires the state to place the water body on a list of impaired waters. The state then determines the pollutant load reductions needed for the water body to meet its water quality standards. This determination is known as the Total Maximum Daily Load, or TMDL.
In 1996, the Port Tobacco River was identified as being impaired by nutrients due to signs of eutrophication. Eutrophication, the overenrichment of aquatic systems by excessive inputs of nitrogen and phosphorus, was evidenced in the Port Tobacco River by recurrent seasonal algal blooms. Land development as well as the addition of point source discharges can increase the rate of eutrophication to problematic levels. Highly eutrophic waters will characteristically have fewer species present, and
dissolved oxygen content will fluctuate between day and night, which can cause fish kills.
A document describing TMDLs for the Port Tobacco River for the nutrients nitrogen and phosphorus was issued in 1999.
Water Quality Mapping
The Maryland Department of the Environment’s Water Quality Mapping Center provides access to information on Maryland’s surface water quality in a geographic format. The Center provides information specific to the Designated Use Classes, Integrated Report (water quality impairments), Tier II high quality waters, and Shellfish Harvesting Area Closure information.