Watershed Special Threats or Challenges

Threats to the Potomac Watershed
Residential Oil Tanks

Without proper care, old and rusted heating old tanks can cause costly leaks and spills. Underground tanks are especially problematic because they can leak for years without notice. Large toxic spills may get all the media-fueled attention, but these silent, slow leaks add up to one major environmental problem for the Potomac River basin and its residents. (ICPRB Website)

De-icing and Anti-icing Chemicals 

De-icing and anti-icing chemicals provide benefits by preventing roadway accidents and slips and falls, but also negatively impact the environment, human infrastructure, and sources of drinking water. Salt is the most commonly used form of de-icing chemical. Potomac Drinking Water Source Protection Partnership has long been concerned about the impact of chlorides on drinking water supply infrastructure and on the treatability of the source water. . (ICPRB Website)

The climate crisis

There are few threats scarier in today’s world than climate change. Increasing temperatures and changing precipitation patterns are expected to cause more extreme droughts and floods. A severe drought in the Potomac could impact the area’s water supply, threatening the drinking water of 5 million local residents.

Heavy rainstorms also cause runoff and sediment pollution, both in the Potomac and in local streams. Some local communities are already flooding more often and faster than they have in the past. In the long term, rising sea levels could have a drastic impact on the District. As water levels are rising, the land is also sinking, making the effects even more severe in our area. The good news is that the Potomac is healthier than it has been in decades. Overall pollution levels are decreasing, fisheries are rebounding, and recreational opportunities along the river are growing. (Potomac Conservancy Website)

 Flooding along the Georgetown waterfront in April 2011

Invasive Species

Invasive plants and animals, many of which were introduced to our area from elsewhere — other states, countries, or continents — are species that harm the local environment.

Invasive plants, like English Ivy, can choke out and kill native trees, which are important in filtering polluted water and stabilizing riverbanks. Invasive plants also destroy native habitat and harm local wildlife. With dwindling funds and a lack of resources, many National Park sites in our area are being overrun by these plants. The Potomac River is also threatened by invasive fish, including the snakehead and blue catfish. Many local biologists argue blue catfish are the bigger threat to the Potomac. They are top predators, can weigh over 100 pounds, and are expanding rapidly throughout the region.

 

Snakehead below the surface in the Potomac

Endocrine Disruptors

There are unknown chemicals in the Potomac that are causing hermaphroditic fish — male fish with female eggs. This “intersex” fish phenomenon is likely caused by endocrine disrupting compounds (EDCs) found in our local waterways. EDCs can find their way into the Potomac through polluted runoff and the wastewater treatment process. These contaminants, found in everyday products such as medicines, cosmetics, and in agricultural chemicals, interfere with normal biological processes by disrupting the hormonal (endocrine) systems that control growth, reproduction, and development in all vertebrate species, including fish and humans. The impact on human health is largely unknown. Many of these chemicals are not removed from drinking water by standard water treatment methods.

 

Threats to the Four Mile Run Watershed as a Direct Tributary of the Potomac River
Water Quality Issues in Four Mile Run Today

Overall, the problems affecting water quality and aquatic habitat in Four Mile Run today can be attributed primarily to the urban nature of the watershed. However, it must be emphasized that there are a number of regulatory and voluntary efforts underway to restore Four Mile Run. Urban non-point source pollution and its related impacts to Four Mile Run can be placed into eight major categories:

1. Quantity and Rate of Flow

2. Loss of Instream and Riparian Habitat

3. Sediment Erosion and Transport

4. Litter

5. Excessive Nutrients

6. Substances without Standards

7. Water Temperature

8. Water Quality Standards

The first and second categories listed are not generally thought of as pollutants, but both the “Quantity and rate of flow” and the “Loss of instream and riparian habitat” are direct results of human impacts on the Four Mile Run watershed and greatly affect the quality of water and habitat in Four Mile Run.

Since the establishment of point source regulations authorized by the Clean Water Act in the 1970s, water quality conditions in Four Mile Run have undoubtedly improved due to improvements in wastewater treatment technology. The primary threat to the long-term health of Four Mile Run and the safety of its users is now caused by urban non-point source pollution and its related impacts. (Northern Virginia Regular Commission-NVRC)