Wetlands Ecology in the Lake Erie Basin

Overview What is a wetland? Case study Types of treatment wetlands Wetlands for water quality Important variables in wetland design Management after construction

Case Study

Wolf Creek Watershed

Maumee Bay Maumee Bay SP Lodge

Beach advisories due to high coliform counts….. Coliform bacteria: Rod-shaped, gram- negative organisms which ferment lactose with the production of acid and gas when incubated at 35-37°C. Coliforms are generally not the cause of sickness, but are easy to culture. Their presence indicates that other pathogens of fecal origin may be present. Escherichia coli (E. coli), is an example of a coliform bacterium. Found in the intestine of warm-blooded animals. Most E. coli strains are harmless, but some can cause serious food poisoning. E coli’s ability to survive outside the body makes them an ideal indicator to test environmental samples for fecal contamination

E. coli from Rain Flush (Berger Ditch, Maumee Bay SP, Aug 24, 2001) Time (minutes) E. coli, Flush Conditions (Thousands cfu/100ml) E. coli, Background Conditions (Thousands cfu/100ml) Source: University of Toledo/Lake Erie Center, June 2003 Recreational use (primary contact) is impaired if the mean fecal coliform content exceeds 1000 CFU/100ml (for no less than five samples/month )

Maumee Bay 2004: E. Coli High E. coli in Maumee River Settle out in shipping channel Low E. coli levels between CDF & park High E. coli levels at Berger Ditch Low E. coli levels at other ditches

Design considerations for E. coli removal …..go to the literature (case studies) Ecological Engineering Wetlands Ecology and Management Wetlands Environmental Science and Technology

Source: Hull and Assoc. 2007

Wetland Design Considerations for E. coli Removal Retention time –Longer retention promotes removal Aquatic macrophytes –Planted systems have higher removal efficiency Substrate conditions –Gravel works better than sediments Water depth –Shallow systems remove more E. coli UV light –High UV (summer) kills E. coli

Overview What is a wetland? Case study Types of treatment wetlands Wetlands restoration for water quality Important variables in wetland design Management after construction

In-stream constructed wetlands Rain gardens After Kadlec and Knight (1996)

Soil cross section of a surface and a sub- surface flow wetland Surface water Sand, soil or gravel

Overview What is a wetland? Case study Types of treatment wetlands Wetlands restoration for water quality Important variables in wetland design Management after construction

What can be treated? Municipal wastewater Mine drainage Stormwater runoff, non- point-source pollution Landfill leachate Agricultural wastewater (dairy, swine, feedlot)

How can wetlands transform pollutants in runoff? Sedimentation (including filtration, adsorption, and precipitation) Volatilization Microbial decomposition Uptake by plants Water Quality

Organic Carbon Export from Wetland-dominated Watersheds Compared with Non-wetland Watersheds Annual Runoff (cm) Export (g C m -2 yr -1 ) Wetland-dominated Watersheds Non-Wetland Watersheds

Summary of effectiveness data for constructed and natural wetlands (after Strecker et al. 1992) Total Suspended Solids (TSS) Ammonia (NH 3 ) Total Phosphorus (TP) Lead (Pb) Zinc (Zn) Constructed Wetlands – Median Removal Rate (%) Coefficient of Variation (%) Natural Wetlands – Median Removal Rate (%) Coefficient of Variation (%) ,

Removal of P from wastewater by several wetlands P removed (%) P loading (g m -2 yr -1 ) > 25 years of wastewater applied < 2 years of wastewater applied

Removal of N from wastewater by several wetlands N removed (%) N loading (g m -2 yr -1 ) < 5 years of wastewater applied > 25 years of wastewater applied

Potential drawbacks of diverting runoff into natural wetlands Changes the hydrology! Eutrophication (inorganic nutrients and organic matter) Habitat loss (herbicides) Ecotoxicological effects (trace metals, organochlorines) Pathogenic effects (coliform bacteria and other agents)

Houghton Lake treatment wetland (Michigan) where treated sewage has been applied to a natural peatland since a & b. Visually-affected area in 1998 (vegetation changes) c.Dissolved inorganic nitrogen levels in inflow and outflow d.Ditto for total phophorus

Overview What is a wetland? Case study Types of treatment wetlands Wetlands restoration for water quality Important variables in wetland design Management after construction

Design requires attention to… Hydrology (“First, get the water right”) –drawdowns, rates of inflow/outflow, detention times, groundwater recharge Basin morphology –gentle slopes (6:1 or better) to maximize the littoral zone, (wetland plants) –multiple inflow locations and avoid flow channelization –variety of deep and shallow areas Chemical loading –loading graphs, retention rates, empirical models Soil physics and chemistry –organic content, soil texture, depth and layering Wetland vegetation –establishment, growth form, species

Overview What is a wetland? Case study Types of treatment wetlands Wetlands restoration for water quality Important variables in wetland design Management after construction

After wetlands are constructed and wastewater has been applied, management may include: Plant harvesting –harvest multiple times per growing season. Wildlife habitat –ancillary goal, but often welcomed Mosquito and pathogen control –adjusting hydrology, introducing chemical or biological control agents Water-level management –pulse stability Sediment dredging –expensive; also removes seed bank and rooted plants. Best done during drawdown

New UT treatment wetlands (aka “rain gardens”) Honors rain garden Lot-10 rain garden

Carolyn Edwards Memorial Rain Garden (July 2010)

Carolyn Edwards Memorial Rain Garden – July 2010

May Sue Cave Honors Rain Garden (July 2010)