Introduction to Stream Restoration - Hydro-Environmental Analysis: Freshwater Environments - page 267

TABLE 8.6
Common Wetland Problems and Corrective Measures

Wetland Damage Reason for Damage Suggested Correction Considerations

Hydrology
Water quality
impairment

Excess sediment or nutrients
in runoff from adjacent
area

Work to change local land use
practices; install vegetated
buffers/swales/constructed
treatment wetlands; install
sediment traps

Sediment traps will need periodic
cleaning; an expert may be needed
to design buffers and swales

Water quality
impairment

Excess sediments from
eroding slopes

Stabilize slopes with
vegetation/biodegradable
structures

Many corrective methods exist; look
for most sustainable and effective
methods

Altered hydrology
(drained)

Ditching or tile drains Fill or plug ditches or drains;

break tiles

Organic soil may have decomposed
so that the elevation of the site is
lower than it used to be

Altered hydrology
(constrained)

Road crossing with
undersized culvert

Replace with properly sized
culvert or with a bridge

Hydrologic expert needed to correct
this

Altered hydrology
(drained)

Former wetland diked off
from its water sources

Remove/breach dikes or
install water control
structures

Substrate elevation may not be
correct for vegetation; add soil or
control water level with low
maintenance structures

Soils
Raised elevation

Soil dumping or ill Remove material Fill may have compressed soil to

lower than initial elevation; take
steps to avoid erosion

Subsidence Soil removal; oxidation of

organics; groundwater
removal

Add ill; allow natural
sedimentation

Fill must support target wetland;
test ill for toxic compounds

Toxic soils By-product of on-site or

off-site industrial process;
dumping; leaching and
concentration of natural
compounds

Treatment systems or methods
appropriate to the soil/
pollutants; remove material;
cover with appropriate soil

Work with experts to choose
treatment methods that cause the
least amount of indirect damage;
choose a different site to avoid
serious toxin problems

Biota
Loss of biodiversity

Change in original habitat Restore native plant and

animal communities using
natural processes

Allow species to colonize naturally;
import species as appropriate

Loss of native plant
species

Invasive and/or nonnative
plants; change in
hydrology; change in
land use

Remove invasive, nonnative
plants (allow native plants to
recolonize): try to reverse
changes in hydrology

Pick lowest impact removal method;
repeat removal as nonnatives
reinvade; alter conditions to
discourage nonnative species

Source: USEPA, An Introduction and User's Guide to Wetland Restoration, Creation, and Enhancement , by the U.S.
Environmental Protection Agency and developed by the Interagency Workgroup on Wetland Restoration, 2003a.

environment for bacteria to thrive, allowing the biological cycles to begin. The biological processes
of a constructed wetland are proven to reduce the levels of biochemical oxygen demand (BOD) and
nitrates through nitriication and denitriication (Cathcart 2008; Wetzel 2001).
Constructed or stormwater wetlands can affect restoration efforts in addition to wetlands con-
tiguous to rivers and streams, or riparian wetlands.