Planning February 2014

Uncovering Forgotten Landscapes

The movement to daylight streams.

By Chris Tramutola

People have always fought nature, attempting to control it to suit their needs. An obvious — and mostly unsuccessful — example: our efforts to manipulate water systems by channeling rainfall, surface flow, streams, river tributaries, lakes, and oceans.

Water systems abide by simple rules, but they also contribute to the complexity and success of all other natural systems. The landscapes surrounding water corridors are often the most diverse and productive — a fact that frequently has been ignored through history. With recent advances in technology this point has become even more apparent, with little change in our practices. We now find our built environment with a mere skeleton of its former hydrologic system and almost none of its former natural systems.

Understanding how we developed these problems requires looking back at the unforgiving development practices of the 19th and early 20th centuries. We should take note of our responsibility to fix the tragic outcomes, including inappropriate channelization. Can we restore some of these hydrologic corridors without negatively affecting current human uses? If so, can the corridors function ecologically? Finally, for new projects, is daylighting always the goal, or are there instances where covering a stream or leaving it covered is the right answer?

In the 1920s, a federal project buried the saw Mill River in Yonkers, New York. Today, the waterway is once again the centerpiece of downtown, thanks to a coalition effort. Future phases include removing buildings and parking lots that still remain in its way

In New York

In the early 1900s New York City and its surrounding communities were developing with extraordinary speed. Factories littered the urban environment, and the wetlands and waterways that crisscrossed the area were drained and paved with little regard for their ecological importance. Stormwater was deemed a nuisance, and the engineering solution — draining the collective flows into subterranean pipes — persists as standard practice today.

At that time, Yonkers, New York, was developing as an industrial center servicing Westchester County and the Bronx. Located at the juncture of the Saw Mill River and the Hudson River, the surrounding downtown exploded with dense development.

In an effort to help the Yonkers downtown handle the extremely rapid development and flooding issues, a U.S. Army Corps of Engineers project that was completed in 1922 diverted 2,000 linear feet of the Saw Mill River into a large culvert. The surrounding wetlands and floodplains were filled in as part of the urbanization project. Although it did enable denser construction, the project closed off the landscape from any considerable natural production, and created a cold, unforgiving space for its residents.

In 2012, after the Saw Mill River Coalition — a partnership of nonprofit groups, government agencies, municipalities, and businesses — convinced New York State to allocate $34 million for a restoration project, the Saw Mill River in downtown Yonkers was finally daylighted, 90 years after being covered. Roughly 500 feet of the river have been uncovered in the center of town to create an urban park, gathering area, and a place to connect with the larger natural environment.

In contrast to the concrete channel, the daylighting project created a natural riverbed with suitable vegetation, stream banks to aid with surge stormwater flows, and public space in the downtown. Existing buildings and utilities prevented the floodplains and wetlands from being restored, however.

Daylighting may not restore considerable natural process to the Saw Mill River outlet, but it does educate and remind people that the natural environment still exists beneath the thick pavements of urban areas. In the long run, this may prove to be more powerful than any other factor.

Design impact

Restoring natural systems is hard work. The projects tend to be extremely expensive and show nearly no immediate human benefit. So why do we care about daylighting? Until recently, economic and social impacts were the only factors that could be somewhat measured. With recent research ecological processes and services have come into the realm of quantitative analysis, too.

By measuring water pollution levels, vegetative production, biodiversity, air quality, and carbon sequestration, we can see how a functioning landscape helps create a measurably healthier city. The information is gathered using an array of technologies and methods, often grid sampled, averaged, and placed as metadata in modeling programs. Planning and statistical programs such as InVest 2.0 (ARC GIS plug-in) and iTree connect this information to the designer, and have made large strides in quantitative evaluations for the landscape architecture and planning professions.

These tools constantly update studies and available information to help portray the real impact of development and landscape alteration. One example comes from a study performed by the U.S. Forest Service and published in the Journal of Environmental Pollution.

Twenty-eight cities and six states were surveyed for the value and service their large-scale vegetation holds. One finding: New York City's 5.2 million trees not only hold 1.35 million tons of sequestered carbon, but also remove 2,202 tons of airborne pollutants from the air each year — a result that is valued at $10.9 million dollars annually.

While practices that restore or preserve natural function often lead to ecologically sound results, the data may not always show that daylighting is the right path. For instance, nonpoint source pollution contributes to over half of the waterborne pollutants in the U.S. According to the U.S. Environmental Protection Agency, states report that nonpoint source pollution is now the leading cause of water-quality degradation.

Depending on the quality of the stormwater runoff, bioswales and detention basins may suffice. But with heavier concentrations of pollution, treatment facilities may be needed before stormwater can be released into natural landscapes.

In those instances, keeping the surface flow off pervious surfaces would be advantageous, even if that's not considered "green." Pollutants would be kept from filtering down into the groundwater or water system. There is no single right answer for every project.

Limiting urban sprawl is and has been a major goal for the planning profession. Great strides have been made to restrict it, but with a growing population it will never completely halt. That is why ecological links should be retained; preservation or reclamation of streams and tributaries would make the logical avenues for these connections. Daylighting examples abound both in the U.S. and around the world, and much can be learned from them.

A family crosses the Cheonggyecheon River in Seoul, which has been paved over and covered by an elevated highway until its 2005 restoration

In the suburbs

Daylighting projects aren't uniform. Goals may include pedestrian parks, enticing views, and recreating ecological corridors.

One notable project centers on Lick Run Creek, which runs through Hamilton County outside Cincinnati. This was only the second county established in the Northwest Territory of the U.S. It was organized in 1790, but most of the existing development was built in the 20th century — beginning with the piping of Lick Run in 1907. The area averages about 2,000 people per square mile, putting it at the lower end of suburban density in the U.S.

Given the volume of Lick Run, and additional runoff from impervious surfaces, the storm culvert was built with an inside diameter of 19.5 feet. The entire watershed was linked by a network of storm and sewer pipes (now a typical practice). Over the decades, with the buildup of development and impervious surfaces, the combined storm and sewage system has overflowed more and more often, resulting in the discharge of untreated sewage into Mill Creek.

The U.S. EPA issued a consent decree in 1997 to force the county to remedy the situation. In May 2013, the EPA approved a combined sewer overflow solution.

Sewage overflows during medium and heavy rainfalls became a compelling reason to expedite the project. Phase 1, which recently began, will last through 2018, when Phase 2 will kick in. The Metropolitan Sewer District of Hamilton County, the lead agency on the project, has analyzed the hydrologic systems and surrounding landscapes and is now restoring key pieces of the natural ecology.

Total project costs are estimated at $1.14 billion for Phase 1 and $2.1 billion for Phase 2. Funding is being provided by the U.S. EPA, the state of Ohio, and the Hamilton County MSD. Their respective responsibilities were outlined in the Wet Weather Plan created by the U.S. and Ohio environmental protection agencies in 2009.

Two general strategies were adopted: daylighting tributaries that lie within ecological corridors and creating bioswales and water-quality basins that intercept stormwater before it enters the existing storm sewer.

One overall aim is to increase landscape productivity, as measured by carbon storage in vegetation, increase in pervious surfaces, filtration of airborne pollutants, and habitat creation. Water pollution is expected to drop and to keep dropping as the vegetation is established. Both strategies will slow the speed of stormwater.

When completed, the project will reduce stormwater runoff by close to one million gallons annually and drastically slow surge volumes, helping to prevent sewage overflows. Because these problems are costly, there is a clear advantage to reestablishing the natural landscape for more than aesthetic reasons.

In the city

Longfellow Creek in Seattle has a more urban setting. A new project for the water course seeks to reestablish the former environmental corridor while being sensitive to its current utilitarian uses. This long-term project is planned to include small intermittent changes aimed at restoring natural processes, biodiversity and habitats, and the stream and surrounding landscape.

West Seattle, which surrounds Longfellow Creek, was an independent city before being annexed by Seattle in 1907. The creek was covered in the mid-20th century in an effort to control its hydrology and impose grid developments, in keeping with standard development practices of the time.

Sixty years later, in 2004, a master plan for the long forgotten natural causeway was adopted to restore the function, beauty, and allure of the landscape. The plan is part of the Longfellow Legacy project, an ongoing campaign consisting of minor alterations to local creeks, wetland restoration, ecological amenities such as stream ladders for salmon, walking trails with signage, and benches.

Although a long process, this type of design work shows how planning and landscape architecture can approach a project ecologically. It is often typical for a site, campus, town, or city master plan to concentrate on how human uses and buildings evolve, the natural landscape considered a static feature that is forcefully maintained. By performing a separate or adjoining master plan for natural processes that can be observed, altered, and reconsidered, we give them a chance to evolve on their own — a system called self-designing.

man and his granddaughter play together along the Cheonggyecheon River, which is now a destination for picnicking and relaxing

Overseas example

Although streams were generally the most practical water bodies to cover and control during the early 20th century, in rare instances rivers saw the same fate. After the Korean War, the influx of residents to Seoul, South Korea, required rapid expansion — but it was done with little planning. Many residents moved near to the Cheonggyecheon River, an area considered a slum that was already in ecological disarray.

Over the next 20 years the neglected urban waterway was gradually covered by adjacent low-income developments. In 1976, seeing no hope for the river, the city transit authority constructed a six-lane highway above it. For many years, this was the state of the landscape in Seoul, until local residents began to promote ecofriendly and historically sensitive design. Eventually focus turned back to the covered river and its neglected state.

The restoration of the Cheonggyecheon River proved to be expensive and controversial. Daylighting the river involved moving a major thoroughfare, restoring two historic bridges, and reclaiming the natural hydrologic system. The project was completed in September 2005 at a cost of $900 million.

Although the ultimate aim was to convert the area into a pedestrian park and tourist destination, the project also has prompted the residents of Seoul to lobby the city for a long-term strategy for ecological restoration. They understand that a damaged landscape needn't be damaged forever.

Pointing in a new direction

Back in the U.S., some rivers had been in a sorry state even longer. New York City's Commissioners' Plan grid, adopted in 1811, made Manhattan a haven for development but not for nature. Today, there are no remaining natural streams on the island, and storm surges during heavy rains rinse polluted discharges directly into the Hudson and East rivers.

Meanwhile, evidence of the former natural landscape can be found all over the city — from the various street names (Canal Street) to the extra-wide rights-of-way that cover subterranean streams. West 106th and 110th streets in Manhattan are prime examples. Although 106th Street is not a particularly busy street, its 90-foot-wide right-of-way (most New York streets are 55 to 65 feet) hints at the buried waterway below.

Could 106th Street be closed off to vehicular traffic in spots and converted to a vibrant and productive landscape? Not only would the daylighted stream increase productivity, it would also connect the north end of Central Park to Riverside and Morningside parks. Looking for and taking advantage of these opportunities will not only make the city a nicer place to live, but re-establish important natural services.

Our responsibility to our environmental context is obvious, albeit complicated. We are directly connected to the environment in which we live and will have to continue manipulating it, but if we are to sustain an ever-growing population, there are wrong and right ways to proceed.

It would be naive to think that our mistreated natural systems can be restored to 100 percent of their natural glory, but it may be possible to restore enough so that they can contribute and connect to the larger systems they were once a part of. By daylighting streams, we can undo some of the projects that are no longer in step with our more sophisticated understanding of the environment and humans' place in it.

Chris Tramutola is a licensed landscape architect specializing in academic and recreational landscapes. His interest in ecological modeling as a design tool has led to research and experimentation in connection with the future of analysis and design. Contact him at


Images: Top — In the 1920s, a federal project buried the saw Mill River in Yonkers, New York. Today, the waterway is once again the centerpiece of downtown, thanks to a coalition effort. Future phases include removing buildings and parking lots that still remain in its way. Photos courtesy Groundwork Hudson Valley. Middle — A family crosses the Cheonggyecheon River in Seoul, which has been paved over and covered by an elevated highway until its 2005 restoration. Photo by Jean Chung/The New York Times. Bottom — A man and his granddaughter play together along the Cheonggyecheon River, which is now a destination for picnicking and relaxing. Photo by Jean Chung/The New York Times.

Saw Mill River: and

Lost Rivers ( is a film about uncovering the Saw Mill River and other waterways.

NYC 106th and 110th street streams:

Lick Run Cincinnati:

Longfellow Creek Seattle:

Cheonggyecheon River, Seoul: