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The Goals of Combining Parks and Stormwater

The following is an excerpt from City Parks, Clean Water, a report by the Trust for Public Land’s Center for City Park Excellence that examines the role of urban parks in managing stormwater. This is the seventh installment in a series of 19 posts.

City parks departments and water agencies both stand to benefit from designing parks for stormwater management. However, it isn’t always easy to meet the needs of both parties, as well as those of the citizen users of a park. For one thing, stormwater has a complex range of impacts, and the techniques for dealing with those impacts are not easy to carry out, or even to explain to the public. There are also many different kinds of park users who have vastly different opinions about what makes a park great and what degrades it.

Beyond the multiple agency goals, there are also citizen issues that can make compromise challenging. Both water systems and recreation are highly complex topics that have their own languages, acronyms, and nuances, so public conversations can be difficult. The historical separation of the recreation profession from the stormwater business means that many park and water agencies are new to the interplay of issues that might arise. Plus, cities by definition are dense places; trade-offs that might be easy where the spaces are wide open can become more difficult where every acre counts and each group has an agenda.

From the perspective of water agencies there are four principal goals, each of which can play out in a public park:

  • Reducing stream pollution by holding and slowing water. Bioswales, rain gardens, and vegetated buffer strips in parks can detain stormwater so that a downpour doesn’t wash out large quantities of sediment and pollutants. The swales also filter out chemicals, animal waste, oils, and heavy metals and improve the quality of the runoff. One of the nation’s preeminent examples of this at work is in Atlanta’s Historic Fourth Ward Park.
  • Preventing localized flooding. Flooding is a catastrophic and expensive problem—from 2005 to 2014, U.S. flood insurance claims averaged more than $3.5 billion per year. In the worst low-lying situations, the most cost-effective solution may be to remove structures and turn the area into parkland that periodically inundates. With less severe cases, it may be practical to direct some of the upstream stormwater into a nearby park.
  • Recharging groundwater. Allowing rain to percolate into the soil is critical since groundwater is the nation’s major source for drinking and irrigation. It’s particularly important in western states (where water is scarce) and in coastal communities (where overdrawn aquifers get filled by the salty ocean).
  • Providing sewer rate-payers with more visible and tangible benefits. Although traditional gray infrastructure can successfully transport and treat stormwater, it is expensive and provides only the unitary benefit of pollution conveyance. In contrast, green infrastructure in parks provides multiple benefits that are visible, usable, and enjoyable to the public that is paying the bills.

    deep tunnel - Tunnel boring machine Nannie Washington DC - credit DC Water

    A deep tunnel boring machine in Washington, DC. Water-smart parks can help cities avoid having to build gray infrastructure such as this. (DC Water)

For park agencies there are two major goals that can be furthered by collaboration with stormwater utilities:

  • Contributing to improved park hydrology. In hilly cities, water racing into parks can not only flood playing fields and undermine trees, but also wash out streams and dump sediment downstream. Since every new swale and detention pond slows the runoff and reduces the burden on waterways and treatment plants, it may be cost-effective for stormwater utilities to help pay for these improvements on parkland. Moreover, these features can serve as attractive, ecological alternatives to the wasteful and dangerous practice of putting drains in the middle of grassy recreational fields.
  • Saving money on irrigation. Just like private citizens, many park agencies have topay for water, which can be a substantial expense. (Even if the bill is picked up by the government at large, it’s still a cost to taxpayers.) Beyond that, some agencies pay a stormwater or drainage fee to a sewer agency based on the size of their property holdings and the percent of their impermeable land. Therefore, the less water sent down the drain, the more water is available to feed the parks – and the more funds are freed up for programming and other needs. Even better are situations where park departments are financially rewarded for saving water. According to a 2014 Trust for Public Land survey, about 14 percent of park agencies, including those in Seattle, Minneapolis and Cincinnati, are given a rebate for water that parks treat and manage, keeping it out of the sewer system. This arrangement gives the agencies an additional financial incentive to creatively modify some of their parkland.

While achieving every goal of every player involved may be difficult, certainly with some collaboration and discussion all parties—and their park—can benefit.

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