EPA: Threats to Wetlands

In September 2001, the EPA published “Threats to Wetlands”  (PDF) to encourage conservation. We reproduce excerpts here, emphasizing some passages with red type. While the national rate of wetlands loss has slowed since the 1970s, Northampton threatens to go against this trend with its proposed wetlands ordinance. This ordinance invites developers to encroach as close as 10 feet to wetlands in Northampton’s more densely settled districts. An analysis performed by Hyla Ecological Services states that buffer zones of less than 50 feet “are generally ineffective in protecting wetlands”.

EPA: Threats to Wetlands

Destroying or degrading wetlands can lead to serious consequences, such as increased flooding, extinction of species, and decline in water quality. We can avoid these consequences by maintaining the valuable wetlands we still have and restoring lost or impaired wetlands where possible…

More than 220 million acres of wetlands are thought to have existed in the lower 48 states in the 1600s. Since then extensive losses have occurred, and more than half of our original wetlands have been drained and converted to other uses. The mid-1950s to the mid- 1970s were a time of major national wetland loss. Since then the rate of loss has slowed.

The National Audubon Society notes that bird populations continue to decrease as wetlands are destroyed. In the past 15 years alone, the continental duck breeding population fell from 45 million to 31 million birds, a decline of 31 percent. The number of birds migrating over the Gulf of Mexico, which rely on coastal wetlands as staging areas (especially in Louisiana and Mississippi), has decreased by one-half since the mid-1960s. Approximately 100 million wetland acres remain in the 48 contiguous states, but they continue to be lost at a rate of about 60,000 acres annually. Draining wetlands for agricultural purposes is significant, but declining, while development pressure is emerging as the largest cause of wetland loss. Unfortunately, many remaining wetlands are in poor condition and many created wetlands fail to replace the diverse plant and animal communities of those destroyed.

When a wetland functions properly, it provides water quality protection, fish and wildlife habitat, natural floodwater storage, and reduction in the erosive potential of surface water. A degraded wetland is less able to effectively perform these functions. For this reason, wetland degradation is as big a problem as outright wetland loss, though often more difficult to identify and quantify.

What Is Adversely Affecting Our Wetlands?
Human activities cause wetland degradation and loss by changing water quality, quantity, and flow rates; increasing pollutant inputs; and changing species composition as a result of disturbance and the introduction of nonnative species. Common human activities that cause degradation include the following:

Hydrologic Alterations. A wetland’s characteristics evolve when hydrologic conditions cause the water table to saturate or inundate the soil for a certain amount of time each year. Any change in hydrology can significantly alter the soil chemistry and plant and animal communities. Common hydrologic alterations in wetland areas include:

  • Deposition of fill material for development.

  • Drainage for development, farming, and mosquito control.

  • Dredging and stream channelization for navigation, development, and flood control.

  • Diking and damming to form ponds and lakes.

  • Diversion of flow to or from wetlands.

  • Addition of impervious surfaces in the watershed, thereby increasing water and pollutant runoff into wetlands.
Pollution Inputs. Although wetlands are capable of absorbing pollutants from the surface water, there is a limit to their capacity to do so. The primary pollutants causing wet-land degradation are sediment, fertilizer, human sewage, animal waste, road salts, pesticides, heavy metals, and selenium. Pollutants can originate from many sources, including:

  • Runoff from urban, agricultural, silvicultural, and mining areas.

  • Air pollution from cars, factories, and power plants.

  • Old landfills and dumps that leak toxic substances.

  • Marinas, where boats increase turbidity and release pollutants…
What Can You Do?
Nearly 75 percent of all wetlands are privately owned, making it imperative that the public participate in wetland management and protection. Here are some things you can do:

  • Conserve and restore wetlands on your property.

  • Support local wetlands and watershed protection initiatives by donating materials, time, or money.

  • Work with your local municipalities and state to develop laws and ordinances that protect and restore wetlands…

  • Participate in the Clean Water Act Section 404 program and state regulatory programs by reviewing public notices and commenting on applications.

  • Encourage neighbors and developers to protect the function and value of wetlands in your watershed.

  • Avoid wetland alteration or degradation during project construction.

  • Maintain wetlands and adjacent buffer strips as open space.

  • Reduce the amount of fertilizers, herbicides, and pesticides applied to lawns and gardens.

See also:

Press Release: Northampton, MA Citizens Campaign to Protect Their Urban Wetlands, Prevent Flooding
On October 4, Northampton’s City Council plans to vote on an ordinance that would slash the no-build zone around wetlands to as little as 10 feet in many districts. Up to this point, 50 feet has been the general standard, with limited exceptions. Citizens are concerned that the new rules will increase the risk of urban flooding and water pollution, and decrease the attractiveness of in-town living…

The proposed new wetlands rules have been before the city for about two years, yet those who stand to lose the most from this ordinance have not been well heard. These are ordinary citizens who reside in the more densely populated area of Wards 1-4, plus parts of Ward 5. These zones–about 15% of Northampton’s land area–contain a disproportionately large percentage of Northampton’s homes.

Wetlands are a key component of Northampton’s natural drainage systems. The extensive flood damage Northampton suffered under Tropical Storm Floyd in 1999 showed that the city’s stormwater management systems are stretched even under its current wetlands policy. The proposed ordinance threatens to dramatically ratchet up the pressure on many of Northampton’s in-town wetlands.

Northampton’s Flood and Natural Hazard Mitigation Plan: Wetlands Buffers of 100 Feet Are an Effective Flood Mitigation Strategy and Should Be Consistently Enforced

Northampton Open Space Plan: “This loss of habitat and natural flood buffering areas is Northampton’s most serious environmental problem”

Alex Ghiselin, Letter to Gazette: “Don’t let development encroach on our wetlands”
The failure of the storm water system built as a part of the Northampton High School renovation six years ago illustrates why protecting wetlands is so important. Silt has filled the retention pond so there is no capacity to slow a storm surge which now flows unimpeded into the Mill River and contributes to flooding downstream. This accumulated silt also raised the water table and spills ground water into nearby basements…

Springfield Wetland Regulations: “A minimum of a fifty (50) foot undisturbed buffer”

WATERSHEDSS: Major Causes of Wetland Loss and Degradation
Urbanization is a major cause of impairment of wetlands (USEPA 1994b). Urbanization has resulted in direct loss of wetland acreage as well as degradation of wetlands. Degradation is due to changes in water quality, quantity, and flow rates; increases in pollutant inputs; and changes in species composition as a result of introduction of non-native species and disturbance. The major pollutants associated with urbanization are sediment, nutrients, oxygen-demanding substances, road salts, heavy metals, hydrocarbons, bacteria, and viruses (USEPA 1994b). These pollutants may enter wetlands from point sources or from nonpoint sources. Construction activities are a major source of suspended sediments that enter wetlands through urban runoff.

Impervious surfaces

As roads, buildings, and parking lots are constructed, the amount of impervious surface increases. Impervious surfaces prevent rainfall from percolating into the soil. Rainfall and snowmelt carry sediments; organic matter; pet wastes; pesticides and fertilizers from lawns, gardens, and golf courses; heavy metals; hydrocarbons; road salts; and debris into urban streams and wetlands (USEPA 1993a; USEPA 1993c). Increased salinity, turbidity, and toxicity; and decreased dissolved oxygen, all affect aquatic life and, therefore, the food web (Crance 1988). Excessive inputs of nutrients can lead to eutrophication or result in the release of pollutants from a wetland into adjacent water resources (USEPA 1993a).

As runoff moves over warmed impervious surfaces, the water temperature rises and dissolved oxygen content of the runoff water decreases (USEPA 1993c). Increased water temperature, as well as the lower dissolved oxygen levels, can cause stress or mortality of aquatic organisms. Rising water temperatures can trigger a release of nutrients from wetland sediment (Taylor et al. 1990). For example, as temperature rises, sediments release phosphorus at an exponential rate. Thus water temperature increases can lead to eutrophication.

Impervious surfaces decrease ground water recharge within a watershed and can reduce water flow into wetlands (USEPA 1993c). Significant increases in stormwater peakflow rates, and longer-term changes in wetland hydrology, as a result of stormwater discharge, can cause erosion and channelization in wetlands, as well as alteration of species composition and decreased pollutant removal efficiency (USEPA 1993a; USEPA 1993c). Changes in frequency, duration, and timing of the wetland hydroperiod may adversely affect spawning, migration, species composition, and thus the food web in a wetland as well as in associated ecosystems (Crance 1988; USEPA 1993c).

Wastewater and stormwater

Wastewater treatment plant effluent and urban stormwater are a source of pollutants that continue to degrade wetlands (USEPA 1994b). The “aging” of wetlands can occur when wetlands filter organic matter. “Aging” is the saturation of the ecosystem by nutrients and heavy metals over time that results in the reduced effectiveness and degradation of the wetland (Mitsch and Gosselink 1986). Wastewater and stormwater can alter the ecology of a wetland ecosystem if high nutrient levels cause extended eutrophication and metals cause plant and aquatic organism toxicity (Ewel 1990). Iron and magnesium, in particular, may reach toxic concentrations, immobilize available phosphorous, and coat roots with iron oxide, preventing nutrient uptake…

Roads and bridges

Roads and bridges are frequently constructed across wetlands since wetlands have low land value. It is often considered to be more cost effective to build roads or bridges across wetlands than around them (Winter 1988). Roads can impound a wetland, even if culverts are used. Such inadvertent impoundment and hydrologic alteration can change the functions of the wetland (Winter 1988). Road and bridge construction activities can increase sediment loading to wetlands (Mitsch and Gosselink 1993). Roads can also disrupt habitat continuity, driving out more sensitive, interior species, and providing habitat for hardier opportunistic edge and non-native species. Roads can impede movement of certain species or result in increased mortality for animals crossing them. Borrow pits (used to provide fill for road construction) that are adjacent to wetlands can degrade water quality through sedimentation and increase turbidity in the wetland (Irwin 1994).

The maintenance and use of roads contribute many chemicals into the surrounding wetlands. Rock salt used for deicing roads can damage or kill vegetation and aquatic life (Zentner 1994). Herbicides, soil stabilizers, and dust palliatives used along roadwa
ys can damage wetland plants and the chemicals may concentrate in aquatic life or cause mortality (USEPA 1993a)…

Connecticut River Watershed Action Plan: Remove impervious surfaces within 50 feet of streams
To reduce nonpoint source pollution from stormwater runoff, the Connecticut River Strategic Plan proposes the removal of impervious surfaces within 50 feet of streams and the investigation of “functional replacements” (such as the use of permeable pavement) for impervious surfaces within 100 feet of streams, in developed areas (PVPC, 2001). In the urbanized areas, the removal or retrofitting of impervious areas and the implementation of Stormwater Best Management Practices (BMPs) could be beneficial in improving water quality.

EPA: Wetlands and Flood Protection

The Economic Value of Wetlands: Wetlands’ Role in Flood Protection in Western Washington

The Ramsar Convention on Wetlands, “A Global Overview of Wetland Loss and Degradation”