A fourth excerpt from the recently released book published by Island Press called Urban Green: Innovative Parks for Resurgent Cities. In this post, we look at some cities who have created parkland along their waterways.
Every city has streams, and streamside areas offer some of the most attractive sites for parks. But streams also present flooding hazards, and many have been placed in pipes and sunk underground. Getting them back out in the open often involves buying and removing houses or other buildings, which is expensive and politically difficult.
Sometimes a severe flood offers the municipality the opportunity to acquire and demolish badly damaged structures. The greenway through the center of Rapid City, South Dakota, was created when the city resolved to never rebuild in the flood zone after a catastrophic deluge there in 1972. In Tulsa, following the deadly Memorial Day flood of 1984, 528 creekside houses and mobile homes were purchased and removed and a greenway was constructed with soccer fields, tennis courts, trails, and fishing spots. More recently, the Greater Grand Forks Greenway was created when the Red River floodplain was cleared of structures after the devastating flood in Grand Forks, North Dakota, and East Grand Forks, Minnesota, in 1997. The greenway park totals 2,200 acres and includes a campground, two golf courses, a disc golf course, fishing sites, and 20 miles of multipurpose trails.
In contrast, in Houston, the Harris County Flood Control District buys large amounts of land alongside bayous (creeks) in order to provide space for water retention and a buffer for flooding. Today, it has jurisdiction over an amazing 2,500 miles of channels. While the District does not initiate trail projects or manage human use, it is more than willing to partner with other government agencies or even citizen organizations in providing for recreation; its best-known trail, along Bray’s Bayou, serves hundreds of thousands of cyclists and walkers each year.
The Flood Control District receives dedicated tax revenue from all Houston area property owners. However, this is not the only conceivable way to pay for streamside land acquisition. Another possibility would be to upzone the neighborhoods on either side of the widened waterway, allowing for greater density, greater height, more dwelling units, and more property tax revenue — using the bayou park to offer more people pretty views and nearby recreation and to become the seed of new higher-value development.
Another place that has focused a great deal of analysis, attention and money on streams is Mecklenburg County, North Carolina, the county that includes Charlotte. Mecklenburg is perfectly willing — anxious, even — to buy at-risk houses and commercial structures, tear them down, and turn the resulting land into greenway parks. This program is a truly gritty one — not just looking at buying virgin land to avoid future flooding costs, but also looking to fix existing inappropriate development problems from the 1940s, 1950s, and 1960s.
“The best way to totally eliminate the flooding risk is to remove the structures,” says Dave Canaan, the county’s director of water and land resources. “I want a situation where we’ll never have to dispatch our Swift Water Rescue Team.” As of mid-2009, a total of about 120 acres had been purchased in greater Charlotte and 248 structures torn down — most of them after having been flooded numerous times. (These are all “willing buyer-willing seller” situations; in one case, a creekside warehouse owner spurned a buyout offer only to return, hat in hand, after having been catastrophically flooded twice in the following two years.)
In fact, it appears that Mecklenburg County’s streamside park program will be expanding in size. In a 1997 deluge, when seventeen properties that were deemed unfloodable flooded, planners realized that something was wrong with their maps. It turned out that they were out of date and didn’t take into account increased runoff from all the new development. Relying on the maps was like buying a child a child-sized bed and expecting it to last his lifetime. To make sure that never happened again, Mecklenburg used computer mapping to project “ultimate runoff” — that time in the future when the county is developed to the maximum extent under existing law. The result was dramatic. The 100-year flood stage on the average creek jumped up 4 vertical feet — which widened the average floodplain by 180 feet (to 610 feet rather than the previous 430). This is now the standard the county uses in preventing development or buying at-risk properties.
Similarly impressive is the way Mecklenburg County funds the project. About half the money comes from park bonds, the other half from stormwater fees paid by every landowner in the county. Interestingly, the fees are set on a sliding scale based on what percentage of a property is impervious. The more a property is covered by a dwelling or paved for other uses — the more rainwater will run off — the more the landowner pays. (Using analysis of aerial photography, the Stormwater Services Department literally knows the amount of impervious area on each of the 330,000 improved properties in the county.)
Some visible creeks are not in parks but merely run alongside roads. Occasionally it may be possible to decommission and depave one of these roads, convert it into a walking trail or bikeway, and reclassify the streamside land into parkland. When the city of Baltimore created the Gwynns Falls Trail, part of the route used a former road bordering the stream. Some of the road segments had been damaged in storms while others had been so lightly used they were deemed expendable. The intact portions were left alone and simply reclassified as closed to cars; the wrecked portions were narrowed and rebuilt to look like traditional trailway.
“Daylighting” buried streams — bringing them back to the surface — is an appealing concept since water adds so much to a park. But the challenges of daylighting should not be minimized. The expense stems not so much from removing the pipe but from widening and regrading the bed and the floodplain to prevent siltation, erosion, gouging, and the other problems endemic to streams in altered environments. The hydrology and ecology of even a small stream valley is awesomely complex. In the 1980s, St. Paul, Minnesota wanted to daylight Phalen Creek though Swede Hollow Park. When water volumes and the confined topography proved too difficult, the engineers settled on bringing a portion of the flow to the surface while leaving most of it underground in the pipe. In neighboring Minneapolis, when the city wanted to raise up Bassett Creek through a new park, the city had to settle for the less ecologically “real” solution of digging an artificial stormwater pond in the middle of the park and leaving Basset Creek where it was — underground.
One of the few unmitigated daylighting successes occurred in the mid-1980s in Berkeley, California, where a citizen group named Urban Ecology lobbied the city to bring Strawberry Creek to the surface. After a lengthy political effort and the appropriation of $580,000, a 200-feet section of creek was daylighted through a park that had been created out of an abandoned rail yard.
As you can see, the re-naturalization of urban areas can be expensive, incremental, and slow, but well worth the time, money and process.