Rapid, poorly planned development on the land is such a serious threat to the Shenandoah’s water that it has become the fifth most endangered river in the nation.

That conclusion, made by American Rivers in its annual Most Endangered Rivers report released in April, underscored growing concern about the health of the river, which has been plagued by a series of unexplained fish kills in recent years.

“Poorly planned development is marching like a marauding army through the Shenandoah Valley, threatening this fabled river’s priceless recreation, rich heritage, and green vistas,” said Rebecca Wodder, president of American Rivers. “It’s OK for counties to put out the welcome mat, but they shouldn’t be doormats for developers.”

John Eckman, executive director of the Shenandoah Valley Conservation Council, doesn’t take the river’s new description as purely bad news.

“It doesn’t mean that the Shenandoah is one of the top most polluted rivers in the country. It means that the river is endangered, and we have the chance to do something about it,” Eckman said.

The Shenandoah is the largest tributary to the Potomac River, flowing largely through the mountain valleys and rich farmland of northwestern Virginia. The mainstem of the river forms at Front Royal and flows north to converge with the Potomac at Harper’s Ferry, WV.

“The Shenandoah is a peaceful, historic river that defines the Shenandoah Valley,” said Katherine Baer, director of river advocacy for American Rivers. “It was a corridor for pioneer movement and home to Civil War battles. Today, it’s an important resource for fishing and boating, and it’s a very important source of drinking water.”

About 58 percent of the Shenandoah watershed is forested and 38 percent is farmland.

While polluted runoff from agriculture has affected the river, Baer said the Shenandoah farming community has been making progress on river stewardship.

On the other hand, recent years have brought a surge of new construction and a growing population of commuters.

“Frederick County, Harrisonburg and the Rockingham County area have grown tremendously in the past few decades,” Eckman said. “August County is commuting distance from D.C. and has also become a bedroom community for Charlottesville.”

“Acre for acre, urban land use has a much larger impact on water quality than agriculture,” Baer said. “There hasn’t been a focus on what to do about all this urban and suburban development, yet that’s where the trend is going.”

The way new development occurs in the valley is troubling both river advocates and longtime residents.

“Traditional rural communities are getting almost overrun by new development,” Eckman said. “Some of it is haphazard and doesn’t take advantage of what we know can be lower impact development.”

But he is encouraged by the many citizens, developers and public officials who want to find better development models for the valley.

“They want to know what their options are,” Eckman said. “For years, we’ve been trying to get the right language about visions and goals into the county’s comprehensive plans. Most of them have that language now, but they are working hard to get the ordinances that support it.”

The question is whether growth will continue to outpace local efforts to shape it.

“Urgency is the factor this report speaks to, more than the condition of the river,” Eckman said.

While the beauty of the Shenandoah lures many to boat, fish and live in its watershed, the river is not without current troubles. For example, approximately 1,300 miles of streams and rivers in the watershed don’t meet federal clean water standards.

But most notorious is a mysterious series of fish kills that recently wiped out large numbers of smallmouth bass and redbreast sunfish in the river.

“The fish kills are a canary in the coal mine,” Baer said.

The first fish kill appeared on the North Fork of the Shenandoah in 2004, followed by another on the South Fork in 2005. More deaths have been reported this spring in both locations. Juvenile fish and species reproduction have not been affected.

“At first, the number of dead fish is actually quite low. It doesn’t appear to be massive or terribly alarming.” said Don Kain, a manager at the Virginia Department of Environmental Quality and co-chair of the Shenandoah River Fish Kill Task Force. “The problem is that it persists for several months. We lost about 80 percent of the adults of those two species over two to three months.”

The deaths continue to puzzle watchful scientists.

Fish tissue samples showed bacteria, but no sign of disease. The kill has shown up throughout the rivers, with no clear pollution source as the likely culprit. Water quality testing, focused on nutrients and ammonia, failed to turn up suspects. And while the first two occurrences affected only smallmouth bass and redbreasted sunfish, the condition began to appear in other species this spring.

The Fish Kill Task Force, led by the Virginia DEQ and the Department of Game and Inland Fisheries, has beefed up monitoring efforts to nail down the cause of the kills. Daily and hourly water quality monitoring takes place on the North and South Forks, along with an extensive fish study to look for signs of chronic stress.

The task force is also investigating “intersex” fish, which were discovered during tissue analysis from the 2005 fish kill. Intersex fish are individual fish with characteristics of both males and females.

Scientists don’t yet know if the intersex condition is related to the fish kills.

“Until we have good scientific data that clearly tell us what’s going on, we don’t want to jump to any conclusions,” Kain said. “If people see anything out the ordinary, we encourage them to call us.”

American Rivers also urges citizens to help protect the river by supporting sound approaches to development. Baer suggests that citizens write to their county supervisors or planning commissioners, as well as do what they can to minimize hard surfaces and conserve vegetation on their own property.

“We hope that listing the Shenandoah as an endangered river will help people focus on the river and consider it as they make decisions,” Baer said. “The endangered rivers listing can be a real catalyst for positive change.”

To report information related to the Shenandoah fish kills, contact the Virginia DEQ at 540-574-7800.