HABITAT

Previous Grade: C-

Tidal water quality is measured by a combination of dissolved oxygen, water clarity, and chlorophyll a (a measure of algae). Healthy amounts of dissolved oxygen in the Potomac can produce ideal habitat conditions for fish and other aquatic life. Water clarity, a measure of sunlight penetrating through the water column, indicates the amount of suspended sediment, plankton, or other organic matter in the water. Better water clarity helps tidal grasses to grow, which in turn provide habitat and food for fish and other aquatic animals.

Storms and other extreme weather events can cause disastrous river conditions by destroying underwater grasses and rapidly conveying large amounts of pollution into the river. When this occurs, high levels of chlorophyll a, indicating the presence of nitrogen and phosphorus, can create harmful algal blooms. Algal blooms harm aquatic life and impact public recreation locations; they can even starve a river of critical nutrients and oxygen. Algal blooms can also create dead zones, areas with little to no dissolve oxygen that cannot support aquatic life. In 2017, the Chesapeake Bay dead zone was ten percent larger than the previous year. In addition, some blooms can produce harmful toxins called cyanobacteria or microcystin, which threaten animal and human health when ingested and are difficult to remove from drinking water supplies.

The long-term trend for dissolved oxygen began improving in 2011, and, despite a decline in 2016, has increased the past few years to 83 percent (A-) of the goal. Water clarity is showing signs of improvement since a low point in the mid 2000’s, currently measuring 27 percent (D) of the goal. In 2016, chlorophyll a, experienced a decline to 32 percent (D+), meaning chlorophyll a concentrations are increasing (a bad sign for the river). Improvements in water clarity help offset the degrading short-term trends in dissolved oxygen and chlorophyll a. Taken together, the combined average of dissolved oxygen, water clarity, and chlorophyll a meets 47 percent (C) of target goals.*

The Potomac received a “C-” for tidal water quality in the previous Potomac River report card.

*The University of Maryland Center for Environmental Science has created a flow-adjusted measure of water quality for the Chesapeake Bay, but this metric does not yet exist for the Potomac River. The measure of water quality used for this report uses a straight average of the three indicators and may not be comparable to water quality results measured by other agencies or organizations.

Previous Grade: C-

Underwater grasses provide habitat for fish, waterfowl, and other wildlife. These grasses also add oxygen to the water and filter nutrients and pollution. Underwater grasses are sensitive to pollution and extreme storm events, but can quickly recover with water quality improvements, making them a great indicator of river health.

Underwater grass abundance is variable in the tidal reaches of the river. The Potomac experienced an overall 10 percent decline in tidal grasses in 2016 (meeting 40 percent (C-) of the overall goal of 8,580 acres), while portions of the upper Potomac experienced an 18 percent increase. Since underwater grasses in the Potomac peaked in 2005, there has been a noticeable short-term downward trend, despite a long-term positive trend since 1986.* Elsewhere in the Chesapeake Bay, underwater grasses reached record high levels in 2016.**

The Potomac received a “C-” for underwater grasses in the previous Potomac River report card.

*Data are unavailable for the year 1988. The historic average for underwater grass acreage is 4,768 hectares in the Potomac River.

**The apparent decline in 2016 may be due to limitations on data collection (restricted airspace and weather conditions prevented data acquisition on portions of the river).

Previous Grade: C

More than 50 percent of America’s drinking water is stored and filtered by forests; healthy forests keep our water clean. Shoreline trees, also called forested buffers, offer crucial protection from the harmful effects of pollution in local streams and creeks. Forested buffers also provide important habitat for wildlife, reduce erosion by stabilizing river banks, and keep our coldwater streams shaded. Here at home, forested areas in rural Maryland, Virginia, and West Virginia protect the cleanest waters of the Potomac River.

Multiple programs support and promote shoreline tree plantings across the Potomac region. On agricultural lands, the USDA’s Conservation Reserve Enhancement Program (CREP) provides funding and resources to plant trees through multiple partnerships. In urban and suburban areas, localized programs are led by counties, municipalities, or voluntary watershed groups; funding for these projects is often dependent on competitive grant programs.

Across the Chesapeake Bay region, forested buffer programs are falling short of restoration goals. In 2015, only 64 miles of buffers were planted, leaving a gap of 836 miles to reaching the annual planting goal established by the CBP. This was the lowest planting total in the past 16 years.

In the Potomac region, Maryland, Pennsylvania, Virginia, and West Virginia reported a total of 35.5 miles of forested buffers planted in 2015. Potomac Conservancy created a goal of 207 miles planted per year, by scaling the CBP goal down to the size of the Potomac watershed.* The four states met 17 percent (F) of this goal in 2015.

The Potomac received a “C-” for forested buffers in the previous Potomac River report card.

*These data include plantings that may have occurred outside of the Potomac watershed, due to statewide reported data.

Previous Grade: D (data retroactively indicates B+)

Freshwater streams and creeks flow through the forests, farms, cities, and communities that surround the Potomac. The health of these individual waterways can impact the overall health of the river as the water collects and flows downstream. These non-tidal waterways also impact the health of wildlife and fish, provide freshwater drinking supplies, and, when healthy, contribute to a higher quality of life for people living near them.

Unfortunately, poor water quality negatively impacts many of our nation’s rivers and streams, including the Potomac. The Interstate Commission on the Potomac River Basin (ICPRB) developed an index to measure the health of freshwater creeks and rivers throughout the Chesapeake Bay region. Potomac Conservancy established a goal of 70 percent of the sampled stream sites meeting fair, good, or excellent conditions; this is scaled from the same goal established by the Chesapeake Bay Program. The comprehensive 2016 results show an estimated 38 percent of sampled stream sites in the Potomac basin are in fair, good, or excellent condition (meeting 53 percent (C) of the established 70 percent goal).*

The Potomac received a “D” for stream (non-tidal) water quality in the previous report card, though our revised methodology indicates this goal should have been reported as a B+. This results in a short-term decline in non-tidal stream health since the previous report card.

*These latest results are not directly comparable to results from previous years (including the 2016 SONR) because of the dataset updates and index refinement. Therefore, it is difficult to conclude whether stream health has improved, declined, or stayed the same across the Potomac River watershed. The Chesapeake Bay Program intends to develop a baseline for measuring improvement in stream health and function.

Previous Grade: N/A

Bald eagles, one of the most iconic bird species in the Chesapeake Bay and our national symbol, were nearly exterminated during the 1970s by dichloro-diphenyl-trichloroethane (DDT). This poisonous toxin was sprayed as a pesticide and made its way into fish, the eagle’s primary food source (over 90 percent of a bald eagle’s diet is fish). After DDT was banned, the eagle population began making a slow recovery, with the first new nest sighted in the Trough section of the Potomac in 1981. Intensive restoration efforts since the 1980s have brought the eagle soaring back to record numbers.

Conservation groups set out to re-establish 300 eagle breeding pairs across the Chesapeake Bay and today there are more than 2,100 breeding pairs along the Bay. In the Potomac region, the number of breeding pairs increased by 50 percent to 214 in 2016. Several eagle pairs are nesting in DC for the first time since 1946 and, according to the Center for Conservation and Biology at the College of William and Mary, “we have entered a golden era [for] eagles, osprey, and blue herons in the Bay”.

There is no restoration target established for the Potomac River bald eagle population.

The Potomac received no grade for bald eagles in the previous Potomac River report card.

Previous Grade: N/A

The Potomac River and the Chesapeake Bay are home to populations of bottlenose dolphins. Dolphins are good indicator species because they are at the top of the food chain. A healthy dolphin population generally means that the surrounding habitat is supporting the appropriate amount of prey species at lower levels of the food chain. Individual dolphins may inhabit hundreds or thousands of square miles, traveling through rivers, bays, and oceans.

Dolphins, particularly Potomac River dolphins, are receiving extra attention lately, which could be the result of increased press and social media coverage, or might be related to cleaner waters and healthier habitats. Researchers are studying the Potomac River dolphins to understand how many live in the Potomac, where they travel, whether or not their numbers are increasing, and possible reasons why.

There is no restoration target established for the Potomac River dolphin population.

The Potomac received no grade for dolphins in the previous Potomac River report card.

Habitat indicators capture the quality of lands and waters in the Potomac, revealing the ability to support healthy populations of wildlife. To assess overall health, we use data from six areas, including tidal water quality, underwater grasses, forested buffers, non-tidal water quality, bald eagles, and dolphins.

Forested buffer information is reported separately for different governmental programs, based on jurisdictions, which makes it difficult to define specific goals and trendlines. For example, CREP data is reported by the Farm Service Agency (FSA), a division of the USDA. CREP data reports acres of practice implemented; types of practices include planting trees, restoring wetlands, creating habitat for birds or pollinators, and more. Data is reported by county and then by state; there is not yet a reporting mechanism that looks only at the Potomac region, so data often includes portions of counties or states that fall outside of the Potomac region boundaries. Finally, CREP is a voluntary program, which relies on farmers, ranchers, and agricultural land owners to enter into agreements (typically 10-15 years) to implement river-friendly best management practices (BMPs).

There is no complementary program that exists for forested buffer plantings in urban and suburban areas. These areas rely on other types of programs, often with funding from state and local governments or grant programs, to plant and maintain trees. With no consistent framework, data is difficult to capture for these areas. Furthermore, the Chesapeake Bay Program tracks and monitors forested buffers in miles, not acres, making it difficult to consistently compare trends over time.

Other forested buffer programs include local initiatives like Frederick County’s Creek ReLeaf Program and voluntary plantings led by watershed groups (including Potomac Conservancy). The 2016 Chesapeake Bay Program’s “Bay Barometer” showed a significant, long-term declining trend in forested buffer plantings (reported in miles). As one of the cheapest and most effective river-friendly practices, this decline in forested buffer plantings is worrisome to officials across the region. While cost-sharing programs exist to share the burden of planting these buffers, flexibility, funding, and coordination challenges continue to result in slow implementation efforts.

Data for the Habitat indicator are provided by the EPA Chesapeake Bay Program, the University of Maryland Center for Environmental Science, the Interstate Commission on the Potomac River Basin, and the Center for Conservation and Biology at the College of William and Mary.