| |
Wetlands and Aquaculture - Can Work Together | |
| |
|
|
| |
.
Max Menard, of Smoky Trout Farm, near Red Deer,
standing tall, next to their constructed wetlands and a healthy
stand of cattails. The wetlands have only been functioning for
a year.
Dan’s first call was to the Federal Prairie Farm Rehabilitation Administration (PFRA) in Red Deer. The local water engineer provided Dan with designs and specifications to make a wetland work. The Menard’s wetland was completed in spring of 2003; now the cattails and vegetation are thriving.
How do wetlands work?
Wetlands are areas of land often saturated by surface or ground water, enough to support the growth of water-loving plants. Wetlands act in combination with vegetation, soil, water and microorganisms that act as waste purifiers for the water. Plants slow the water flow through the system, creating adequate retention time for treatment and help by absorbing some of the contaminants.
Microorganisms living on the vegetation eliminate most nutrients by transforming them into body tissue and less harmful chemicals. Phosphorus and bacteria also end up being bound to wetland soils and buried by inflowing sediment and dead plant matter. Sunlight helps remove bacteria, through ultra violet radiation.
Designing a wetland
According to Sandi Riemersma, surface water quality specialist with Alberta Agriculture, Food & Rural Development (AAFRD) “When constructing wetlands, farmers need to consider: quality of the water to be treated, end use of treated water, slope of the land, type of vegetation / soil, and local climate. It is important that location of the constructed wetland does not negatively impact groundwater or surface water.”
Alberta’s recirculating aquaculture facilities generate low volumes of wastewater (about a toilet flush every few hours). Thus, the size of wetland should be relatively small. The holding capacity should be able to handle at least twelve days of flowing water. To keep aquatic vegetation thriving, maintain water levels a minimum 30 cm depth.
Two fish farms in Alberta are using wetlands to help clean up their effluent. Results will vary among systems; one facility (Greenview Aquafarms) showed suspended solid reductions to nearly 75%, with phosphorus and organic matter levels being reduced to nearly 50%. Greenview’s wetland system is very simple, relying mostly on settling out and solar irradiation.
What about assistance with wetlands? Well, you could contact the Province’s (AAFRD) nearest agriculture water specialist or see a local Federal PFRA office for information on design & construction. It wouldn’t hurt to ask if there’s any funding assistance available, possibly through environmental farm stewardship programs.
The contents of this page are no longer available.
|
|
| |
|
|
| |
This document is maintained by Stacey Tames.
This information published to the web on July 26, 2005.
Last Reviewed/Revised on January 19, 2006.
|
|