Rock Creek Park was designed to be a wilderness in the city. That is a challenging ecology to protect.
It's tough maintaining an urban park.
Beyond the forests, meadows and streams of Rock Creek valley, the city continually intrudes on the Park's ecology—its web of life in which countless species of plants and animals interact with each other and with their environment.
Because of the air pollution of a large metropolitan area, acid rain poisons the streams and high summer ozone levels stress trees and plants.
Dense development paves over the places where water can soak into the soil. Rainfall then carries pollutants like road salt and fertilizer into the creeks.
Sometimes pollutants come from human activity—as in the 1990 leak of 8,000 gallons of heating oil behind a Connecticut Avenue condominium and the massive fish kill in 2000 when an exterminating company employee washed pesticides down a storm drain.
Geysers of Sewage
A long-outdated sanitation system lets raw sewage seep into the creek beds. Most dramatically, several manholes nearly exploded like geysers in June 1952 when the main trunk sewer line parallel to Rock Creek became overloaded by sewage from DC and Montgomery County. One site dubbed "Old Faithful" spewed sewage at a rate of 20 gallons per second.
Less spectacular spills happen after any hard rain because parts of the DC sanitation system combine sewage and stormwater in the same pipe. Whenever stormwater inundates the system, raw sewage is dumped into local waterways. These overflows happen about 30 times a year into Rock Creek and 75 times annually into the Anacostia and Potomac rivers.
Unusually heavy downpours also overwhelm water habitats, flood buildings, undermine roads and trails, and wash away bridges, trees and picnic tables.
Invaded by Pests, Plants and Bambi
Non-native vegetation is crowding out local species. Though English ivy aggressively chokes trees and ground cover, it has long been a popular landscaping plant—introduced by both homeowners and the planners who designed Meridian Hill and Montrose Parks. Japanese honeysuckle was a significant part of the Olmsted Brothers' 1918 plan for Rock Creek Park—yet it outcompetes nearly all native foliage in its path. These and other pernicious plants—including porcelainberry, mock strawberry, garlic mustard and celandine—also get a foothold when seeds are transported by birds or the wind and when landscaping waste is dumped in or near the Park.
Other invaders include non-native insects—gypsy moths, emerald ash borers, and an aphid-like bug that destroys hemlocks and firs—and various fungi that cause chestnut blight and Dutch elm disease and attack flowering dogwoods.
The area is also being overrun by white-tailed deer. They damage existing plants, eat tree seedlings so that the forest can no longer regenerate and take food and cover away from other wildlife. A 2009 natural resource assessment called the overabundance of deer the Park's "largest internal threat." The National Park Service established an initial goal of reducing the deer population to 15 to 20 per square mile—down from the 82 per square mile estimated by sampling in 2007.
Meanwhile, climate change promotes weather extremes and upsets the age-old calendar of the seasons.
Preserving Our Park
These challenges are being taken seriously. Rock Creek Park has a management plan to try to control the deer population. Groups such as Rock Creek Conservancy and Dumbarton Oaks Conservancy recruit "weed warriors" to root out invasive vegetation. Horticulturalists fight insects and disease with biological and chemical controls, pest barriers and new plantings of resistant species. Area gardeners are favoring native plants.
Within the Rock Creek watershed, neighborhoods are marking storm drains with reminders that anything going down the drain can flow into the creek. Households are taking advantage of programs and grants to plant trees and to reduce stormwater runoff by installing rain barrels, rain gardens and permeable walkways and driveways. In two sites off Oregon Avenue and one adjoining Broad Branch, the District has built a series of pools descending in steps to slow the flow of stormwater runoff and filter out impurities before they reach the streams.
Finally, a massive project by the DC Water and Sewer Authority would bore several huge tunnels near Rock Creek and the Potomac and Anacostia Rivers. These tunnels would hold the combination of sewage and stormwater even during extreme cloudbursts, preventing a sewage overflow. At this time, however, WASA is proposing to forgo building the Rock Creek tunnel at Piney Branch and reduce the size of the planned Potomac tunnel. The agency would instead fund green programs aimed at keeping water from washing into the system.
It will take the collective effort of residents and governments, volunteers and organizations to preserve the oldest urban park in the National Park System as a natural oasis within the Nation's Capital.