One measure of a river’s health is the vitality of the fish living in the river. On the Potomac, we have three main problems: the decline of fish populations, intersex/sick fish, and fish kills. The three problems are related, and factors that contribute to one — to some degree — contribute to all three.  

Spawning obstacles - When it comes to the decline of fish populations, spawning obstacles are a major cause. The largest spawning obstacles present are dams along the river. When a fish reaches a dam, it cannot continue swimming upstream. Culverts (pipes constructed under roads that allow a river or stream to pass through) also present obstacles to fish. Waste from factories and homes contribute to the decline of fish populations, as waste can kill both the traveling fish and the eggs. Even if it is not lethal, waste can reap other consequences on fish and their eggs.


Sick/Intersex Fish Issues – Strong, healthy fish populations are necessary for the restoration of the Potomac and its tributaries.  Fish are the most visible signs of river health, and are an important part of the ecosystem. A rampant disease is currently plauging fish populations in the Potomac and Shenandoah Rivers: the occurance of intersex fish. Intersex means that fish are born one sex, but develop characteristics of the other sex.

In the Potomac, male fish are developing female eggs on their sex organs. Certain pollutants, namely hormone disrupters, interfere with animals’ reproductive systems. These pollutants come from runoff from animal waste, insecticides, soaps, cosmetics, and medicines that discharge into the water. The USGS found 80-100% of the bass in the South Branch of the Potomac River in 2004 were intersex. Similar fish were found in the North and South Forks of the Shenandoah River and the Cowpasture River in 2005. The USGS recently published a study linking intersex fish with farming activity. You can read more about the study here. In October of 2006, Ed Merrifield--the Potomac Riverkeeper--testified before House of Representative's Committee on Government Reform over the intersex condition. You can read his testimony here.


Fish Kills – While the periodic appearance of a few dead fish on the surface of waters can be expected (fish die from old age, stress, predation, and bodily injury). Large amounts – and different kinds – of dead fish appearing on the surface is cause for concern. Sadly, there have been seven major fish kills in the Potomac watershed in the last few years. In fact, recreational fishing along the Shenandoah River has been largely wiped out over the past five years, with fishing guides quitting the business because of a lack of fish and good fishing opportunities.

In addition to the fish kills, there have been scattered reports of dead fish and fish with lesions. Fish kills happen for a variety of reasons — depletion of oxygen in the water, parasite infestation, high temperatures, and chemical toxins. Many factors are known to contribute to the problem, and an example of one that consistently shows up in the Potomac watershed is the presence of industrial poultry farms. These farms generate large quantities of poultry waste that is often piled up on site or spread as fertilizer in farm fields, where rain can wash this waste (along with nutrients, bacteria and heavy metals) into the nearby rivers and streams.