Flooding And Green Infrastructure

The Chautauqua region suffered from exceptionally heavy rainfall and flooding two weeks ago, so it seems timely to talk about “green infrastructure” and how it relates to flooding, flood damage, erosion and water quantity and quality.

Green infrastructure is the interconnected network of waterways, wetlands, woodlands, wildlife habitats and other natural areas that support native species and clean water and, consequently, community health and quality of life. According to the US Environmental Protection Agency, “Green infrastructure is an approach that communities can choose to maintain healthy waters, provide multiple environmental benefits and support sustainable communities.”

“Unlike single-purpose gray stormwater infrastructure, which uses pipes to dispose of rainwater, green infrastructure uses vegetation and soil to manage rainwater where it falls. By weaving natural processes into the built environment, green infrastructure provides not only stormwater management but also flood mitigation, air quality management and much more.” (water.epa.gov/infrastructure/greeninfrastructure/index.cfm).

The EPA recommends that your community be it a village, city, town or county should identify, conserve and restore those natural landscape features that provide important water collection, storage, filtration and delivery functions. These can also provide important wildlife habitat or fisheries habitat, contribute to the production of forest products to the community and sustain clean water supplies by recharging groundwaters for private and public wells and reservoirs. Conserving and enhancing the water absorption and storage capabilities of forests, fields, floodplains, wetlands and stream corridors can help reduce the amount of flooding to downstream properties and communities and ensure that groundwaters are recharged so that, during droughts, wells don’t go dry and streams continue to hold and discharge waters in order to maintain lake levels.

The Chautauqua Lake watershed is not a natural, pristine watershed. Many of the natural water storage areas (floodplains and wetlands) have been lost to development. In the most extreme case, the Chautauqua Mall, the site was previously occupied by a large wetland at the confluence of several streams. Not only did we lose the green infrastructure features there, but it was replaced with approximately 45 acres of impervious pavement and rooftops. No provision was made to replace the water storage capacity of the wetland or store the water from the impervious acreage.

Our watershed forests have also lost much of their water storage capacity. The majority of Chautauqua County lands that were not too steep or too wet to farm were cleared for farming in the 1800s. The rough “pit and mound” topography of a natural forest is lost when fields are cleared and plowed. The second growth forests that make up the majority of land cover in our watersheds are essentially smooth abandoned farm fields with immature trees.

As the Chautauqua Lake watershed has been developed, its ability to capture, absorb and store water has been reduced by replacing more absorptive woodland soils with compacted lawns, rooftops, roads and parking lots. The more land we develop, the more quickly our green infrastructure water system’s capacity is overwhelmed by the volume and force of water concentrated in it. Conventional stormwater infrastructure quickly drains runoff to rivers and streams, increasing peak flows and flood risk. Green infrastructure can mitigate flood risk by slowing and reducing stormwater discharges. Filling in and developing floodplains and wetlands, interrupting drainage patterns and confining and channelizing streams causes stormwaters to misbehave by moving water with more velocity and force, eroding banks, eating away roads and road shoulders, and jumping out of the flood plain, all of which expands the flood impact areas.

The perceived tax base benefits of infringing upon flood plains, wetlands and stream corridors for homes and businesses is borne by the entire community in their tax bills for fixing the gray infrastructure that is routinely damaged by flooding from rainstorm events. Rebuilding road shoulders and repaving, repairing and replacing bridge foundations is very costly. Maximizing the conservation and enhancement of green infrastructure minimizes the cost of gray infrastructure that is needed to manage runoff. In other words, green infrastructure saves taxpayers money and promotes a healthy tax base.

Karen Engel, NYSDEC Green Infrastructure coordinator, suggests that communities inventory their green infrastructure resources, develop a green infrastructure plan and change local laws and ordinances, zoning, etc. to implement the plan. More information on green infrastructure planning and enhancement information is available from the NYSDEC at www.dec.ny.gov/chemical/68199.html and from the Green Infrastructure Center at gicinc.org/. Look at the remaining lowlands and stream corridors in your community and work with your leaders to conserve what we have left.

The Chautauqua Watershed Conservancy works with landowners to conserve green infrastructure. It has established a watershed preserve system with a goal of conserving the water quality, scenic beauty and ecological health of the lakes, streams and watersheds of the Chautauqua region. Please call 664-2166 or visit our website for more information.