State of the Nation’s River
RIVER HEALTH INDICATOR
POLLUTION
Pollution impairs the health of the Potomac River and the lands and waters draining into it. Nutrients (nitrogen and phosphorus) and sediment are the top pollutants harming aquatic life, degrading habitat, and making local waterways unsafe.
In 2015, the Potomac was the only major river in the Chesapeake Bay watershed experiencing both short- and long-term reductions for these three pollutants. Recent data from 2016 shows that short-term phosphorus trends are degrading (meaning more pollution is entering the river) while short-term sediment trends are holding steady without additional improvement. Despite these short-term variations, long-term trends still show continued pollution reductions. And, reasons for these variations are still being studied by watershed experts.
Pollution flowing into the Potomac from agriculture, wastewater treatment plants, and industrial sources is on the decline. And interestingly, researchers found that reductions in nitrogen pollution can be at least partially attributed to air quality improvements driven by the Clean Air Act, particularly in the Upper Potomac region.
Despite these significant improvements in recent years, other sources of pollution threaten the goal of achieving clean, safe water in the Potomac.
Urban polluted runoff continues to increase in the Potomac and the Chesapeake Bay, and is the fastest growing major pollution source over time. In addition, pollution is increasing from septic systems throughout the Potomac region. Other threats, such as harmful bacteria and toxins, could pose challenges as they aren’t regulated or enforced under the federally-led Chesapeake Bay cleanup plan. And, aging septic systems, old pipes, and other infrastructure deterioration can make it increasingly more difficult to address our pollution challenges.
The Chesapeake Bay cleanup plan is responsible for much of the pollution reduction seen in the Potomac and local waterways throughout the region. This cleanup plan promotes action and provides clean water funding for hundreds of local communities. The cleanup plan is working; in 2017, the Chesapeake Bay Program reported near-record highs for water quality throughout the region. But, if federal leadership and enforcement through the EPA continue to deteriorate, state and local actors will increasingly be called upon to step up and meet our clean water goals.
Nitrogen
Previous Grade: A-
Nitrogen levels in the Potomac continue to improve in the long term (since 1985) and in the short term (since 2006). The EPA set a pollution reduction goal for nitrogen loads in the Potomac at 43.3 million pounds per year by 2025. In 2015, the EPA-estimated nitrogen levels and US Geological Survey (USGS) River Input Monitoring (RIM)* data suggests the Potomac is on its way to achieve and surpass established targets, reaching 99 and 95 percent of the goal, respectively.
Looking at state-level trends, none of the Bay jurisdictions are on track to meet their nitrogen reduction requirements for all sectors. Maryland, Pennsylvania, and Virginia nitrogen reductions are falling behind in the agriculture and septic sectors. West Virginia is falling behind in the wastewater sector and all four states, plus DC, are behind in nitrogen reductions in the urban and suburban runoff sector.
Why is this in my water? Agricultural fertilizers, livestock and pet waste, lawn fertilizers, atmospheric deposition, detergents, and automobile exhaust are common sources of nitrogen found in water bodies, including the Potomac. Unfortunately, not all sources of nitrogen are decreasing; nitrogen delivered through urban and suburban stormwater and septic systems continues to increase across the Potomac region as development spreads. Efforts to reduce and filter polluted runoff are beginning to show progress, but more work, including the use of more stringent regulation and enforcement mechanisms, is required to meet stormwater reduction targets.
The Potomac received an “A-” for nitrogen in the previous Potomac River report card.
*Flow-normalized data from the USGS RIM station is used for the 2018 analysis. Observed nutrient loads are highly dependent on weather conditions; flow-normalized data remove the influence of river flow, thus rendering annual loads more comparable over time. RIM data does not include pollution entering the Potomac River in the tidal areas below Washington, DC.
Phosphorus
Previous Grade: A
Phosphorus levels in the Potomac continue to improve in the long term (since 1985) and in the short term (since 2006). The EPA set a pollution reduction goal for phosphorus loads in the Potomac at 4 million pounds per year by 2025. In 2015, the EPA estimated phosphorus levels and US Geological Survey (USGS) River Input Monitoring (RIM)* data suggests the Potomac is on its way to achieve and surpass established targets, reaching 107 and 108 percent of the goal, respectively. Regulatory actions, including phosphate detergent bans and limitations on phosphorus in residential lawn fertilizers, are credited for much of this progress.
Looking at state-level trends, DC and West Virginia are advancing towards meeting phosphorus reduction goals for all sectors. Pennsylvania is falling behind in the agriculture sector, and, in addition to Maryland and Virginia, is also falling behind in the urban and suburban runoff sector.
Why is this in my water? Wastewater treatment plants, agriculture fertilizers, lawn fertilizers, atmospheric deposition, and detergents are sources of phosphorus in water bodies across the country. Throughout the Potomac region, wastewater treatment plants have almost eliminated excess phosphorus from treated effluent; these treatment plants are also making progress to reduce combined sewer overflow events that contribute phosphorus during storm events when wastewater treatment capacity is overwhelmed. In addition, a ban on phosphates in residential lawn fertilizers is also reducing the amount of phosphorus entering the Potomac. Unfortunately, similar to nitrogen loads, phosphorus loads in urban and suburban stormwater runoff continues to increase.
The Potomac received an “A” for phosphorus in the previous Potomac River report card.
*Flow-normalized data from the USGS RIM station is used for the 2018 analysis. Observed nutrient loads are highly dependent on weather conditions; flow-normalized data remove the influence of river flow, thus rendering annual loads more comparable over time. RIM data does not include pollution entering the Potomac River in the tidal areas below Washington, DC.
Sediment
Previous Grade: B+
Sediment levels in the Potomac continue to improve in the long term (since 1985) and in the short term (since 2006). The EPA set a pollution reduction goal for sediment loads in the Potomac at 2.26 billion pounds per year by 2025. In 2015, the EPA estimated sediment levels and US Geological Survey (USGS) River Input Monitoring (RIM)* data suggest the Potomac is on its way towards established targets, reaching 80 and 99 percent of the goal, respectively.
Looking at state-level trends, West Virginia is advancing towards meeting sediment reduction goals for all sectors. Virginia and Pennsylvania are falling behind in meeting goals for the agriculture and urban and suburban runoff sectors. Maryland and DC are falling behind in meeting urban and suburban runoff sector goals.
Why is this in my water? Streambank erosion occurs naturally as streams and rivers wind their way across the landscape; however, excessive erosion threatens water quality, habitat, and public health. Increased urban and suburban development and the conversion of natural landscapes to agriculture or forestry production, changes the rate at which water is absorbed by and flows across the landscape. Removal of streamside vegetation also exposes streambanks to increased erosion. And, like both sediment and phosphorus, sediment in urban and suburban stormwater runoff continues to increase.
The Potomac received a “B+” for sediment in the previous Potomac River report card.
*Flow-normalized data from the USGS RIM station is used for the 2018 analysis. Observed nutrient loads are highly dependent on weather conditions; flow-normalized data remove the influence of river flow, thus rendering annual loads more comparable over time. RIM data does not include pollution entering the Potomac River in the tidal areas below Washington, DC.
Bacteria
Previous Grade: N/A
Bacteria, specifically E. coli, is not included in the pollution reduction targets for the Chesapeake Bay, but is often related to excess nutrient and sediment pollution.
The District of Columbia Department of Energy and Environment found bacteria levels in the Potomac and Anacostia rivers exceeded water quality standards during their 2016 water quality assessment. While urban sources of bacteria in Washington, DC, contribute to high E. coli levels, this is also an indicator of pollution issues occurring upstream from DC, such as from agricultural runoff.
Why is this in my water? Primary sources of bacteria in the Potomac River include agriculture, combined sewer overflows or other illicit discharges of untreated wastewater, leaking septic systems, and wildlife. Livestock with direct access to streams or other waterbodies and insufficient nutrient management on crops and pasture are primary concerns in agriculture. The Shenandoah River and Goose Creek are two Potomac tributaries with bacteria levels exceeding water quality standards due to agricultural activities in the watershed; several groups are suing the EPA over the bacteria pollution found in the Shenandoah River. Urban sources of bacteria include, among others, sewer overflows, stormwater runoff, and illegal dumping. High bacteria levels in water bodies pose health risks to humans and animals, and continue pushing swimmable waters out of our reach.
In 1998, DC Water began a major infrastructure project to construct a series of tunnels under the Potomac and Anacostia rivers. The tunnels will capture and transport combined sewer and stormwater from within the DC and other service areas to the Blue Plains Wastewater Treatment Plant. When completed, the system will eliminate 98 percent of combined sewer overflows during storm events and prevent raw sewage and bacteria from entering the Potomac and Anacostia rivers.
There is no reduction target established for bacteria in the Potomac River.
The Potomac did not receive a grade for bacteria in the previous Potomac River report card.
Resources and Methodology
The Potomac River is part of the Chesapeake Bay Program’s (CBP’s) efforts to clean up the entire Chesapeake Bay watershed. The CBP is a unique regional partnership, consisting of enforcement and guidance provided by the EPA, and partners ranging from the six watershed states and Washington, DC, other federal and state agencies, local governments, non-profits, and academic institutions.
Through this partnership, the various stakeholders created and agreed upon goals for the reduction of nitrogen, phosphorus, and sediment in the Potomac and other Bay rivers by setting a total maximum daily load — or TMDL — by jurisdiction and source (such as agriculture, regulated stormwater, wastewater treatment plants, or atmospheric deposition). The EPA tracks the flow of pollutants by using modeled estimates of pounds per year saved by best management practices (BMPs). Jurisdictions must have programs and projects in place to meet the goals by 2025; an interim check on progress is slated for release in 2018. As the modeling technology improves, it occasionally matches up with pollution loads monitored in the river.
In addition to the modeled data provided by EPA, the United States Geological Survey (USGS) monitors actual pollution loads observed at a non-tidal River Input Monitoring (RIM) station at Chain Bridge on the Potomac River. The RIM station at Chain Bridge is located just upstream from Washington, DC; therefore, pollution from DC and tidal waters is not measured by this data.
A comparison of the non-tidal water quality monitored data (USGS) to the watershed-wide modeled data (EPA) is helpful in assessing pollution trends and produces a more complete picture of the river’s health. Data from the USGS RIM station determines how much pollution is observed in the river entering Washington, DC, while the EPA model simulations assess trends in all pollution sources. Both data sources are critical to meeting TMDL requirements, through this combined process of modeling and monitoring.
The 2016 State of the Nation’s River report included different 2025 targets for nitrogen, phosphorus, and sediment. Conservations with CBP staff indicated that, since the previous report, these 2025 planning targets were revised following discussions with the various Chesapeake Bay jurisdictions. Because jurisdictions are now working towards meeting these new 2025 targets, this report also includes this new data.
The 2016 State of the Nation’s River report included a grade (A) for wastewater treatment discharges, which introduce pollution into waterways. Driven by the Clean Water Act and with funding from federal, state, and local jurisdictions (almost $7 billion of investment), wastewater treatment plants across the region are implementing upgrades to reduce pollutants through new technology and systems. Once a barrier to achieving clean water, this sector now exceeds its pollution reduction requirements throughout the Potomac and the Chesapeake Bay regions. This indicator is not feature in this 2018 report; other pollutant sectors are now the focus of Potomac and Chesapeake Bay recovery efforts. At this time, the report does not include trends for heavy metals, PCBs, temperature, pH, or other pollutants.
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