Constructed Wetland

Constructed Wetland POLLUTANTS ADDRESSED: Nutrients and Organics, Pathogens, Salinity, Sediments

DESCRIPTION: A constructed wetland provides many valuable environmental services. This living vegetation barrier can significantly reduce a variety of pollutants in surface waters. Constructing such a wetland is, however, a complex undertaking, requiring significant engineering expertise.

ADDITIONAL BENEFITS: Provides low maintenance wastewater treatment.

Facilitates groundwater recharge.

Helps to maintain stream flow during dry periods.

Provides habitat for native wetland species POTENTIAL TREATMENT AREAS: Streambanks Agricultural lands Developed lands

LOAD REDUCTION MECHANISM: Organics/Nutrients Management- Nutrients in overland flow and stream water are taken up by wetland plants and absorbed by wetland soils.

Pathogen Reduction- Vegetation filters microorganisms out of the water.

Salinity Reduction- Vegetation absorbs dissolved salts from the water.

Sediment Reduction – The dense vegetation slows water flowing through it and traps suspended sediments.

ALTERNATIVE MANAGEMENT MEASURES: Pole/Post Planting Brush Trench Seeding Irrigation Water Management PERMITTING REQUIREMENTS: Requirements vary by location. A permit under Section 404 and 401 of the Clean Water Act will be necessary. If discharge is involved an AZDPES permit may be required.

Contact county regional flood control district.

LAND USE CLASSIFICATION: Disturbed Areas Agricultural and Ranch Lands

Arid Southwest BMP

33

Constructed Wetland POLLUTANTS ADDRESSED: Nutrients and Organics, Pathogens, Salinity, Sediments and metals

Level 500: INTENSE ENGINEERING LOAD REDUCTION POTENTIAL: LOW

MEDIUM

Riparian Planting Zone: Base flow/Toe Zone

HIGH SOURCES OF ADDITIONAL INFORMATION:

ESTIMATED TIME FOR LOAD REDUCTION: IMMEDIATE

MONTHS2 YEARS

Design manual: Constructed wetland and aquatic plant system for municipal treatment, EPA 1988. http://epa.gov/wetlands/pdf/design.pdf.

> 2 YEARS

EXPECTED MAINTENANCE: LOW

MEDIUM

Brookhaven National Laboratory Technology Fact Sheet: Wetlands Restoration/Constructed Wetlands. http://www.bnl.gov/erd/Peconic/Factsheet/Wetlands.pdf.

HIGH

ESTIMATED COST: LOW

MEDIUM

HIGH

PLANNING AND IMPLEMENTATION: 1. Construct treatment wetlands, as a rule, on uplands and outside floodplains in order to avoid damage to natural wetlands and other aquatic resources, unless pretreated effluent can be used to restore degraded systems.

2. Consider the role of treatment wetlands within the watershed (e.g., potential water quality impacts, surrounding land uses and relation to local wildlife corridors).

3. Closely examine site-specific factors, such as soil suitability, hydrology, vegetation, and presence of endangered species or critical habitat, when determining an appropriate location for the project in order to avoid unintended consequences, such as bioaccumulation or destruction of critical habitat.

4. Use water control measures that will allow easy response to changes in water quantity, quality, depth and flow.

5. Create and follow a long-term management plan that includes regular inspections, monitoring and maintenance.

Arid Southwest BMP

34