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03/26/2013 Retention Ponds Florida-Friendly Landscaping™ Hillsborough County Extension University of Florida, IFAS Retention Ponds – Quick Facts Legislation was enacted in the 1980’s, which required treatment of stormwater Most were built within the past 20 years Largest number in Florida Commonly referred to as “lakes” Image source: Winnipeg.ca. Retention vs. Detention Ponds Retention ponds are designed to RETAIN water. – Permanent pool of water – Water level fluctuates in response to precipitation and runoff from the contributing areas. Watersheds It’s All Connected - Even Retention vs. Detention Ponds Retention ponds are designed to RETAIN water. Detention ponds are designed to DETAIN water. – Slows down water flow – Holds stormwater for a short period of time – Usually dry, except for during or after rain Stormwater Ponds Water after a storm or heavy rain event either: if you don’t live on the waterfront, your land is still directly connected to a nearby waterbody. Percolates (i.e. sinks into) through soil, recharging groundwater (or the aquifer) directly Like a Bowl - A Watershed is the area of land where all of the water that is under it or drains off of it goes into the same place. Aquifer Connection – All watersheds are connected to the underground aquifer, which supplies most of Florida’s drinking water. Image source: Marmaton Wraps. Original image source: FAO – United Nations. 1 03/26/2013 Stormwater Ponds Water after a storm or heavy rain event either: Percolates (i.e. sinks into) through soil, recharging groundwater (or the aquifer) directly OR Runs off of impervious surfaces, where excess water is collected in the retention pond Stormwater Management Systems Prevents flooding by detaining stormwater after a storm event Improves water quality by providing a natural filter for pollutants Wildlife habitat Recreational activities and a neighborhood amenity Original image source: FAO – United Nations. Pond Maintenance - Now What? Turned over to communities to maintain Responsibility applies to all homeowners Ignorance of the importance of pond maintenance Affects pond lifespan, future maintenance costs and property values Communities and environment downstream Lake or Pond Eutrophication Image source: University of Florida. Retention Ponds – Sad Reality In the process of dying Will have to be re-dredged Lifespan: 20 – 25 years Eutrophication Affects: Algae Quantity and type of aquatic plants Water quality Water clarity and depth Fish populations Note: Sometimes Beneficial Process of nutrient enrichment of lakes – Nitrogen and Phosphorus stimulate the growth of aquatic plants, including algae. Caused by natural and human factors – Wastewater disposal – Agricultural practices – Urban run-off (From yards, golf courses, shopping centers and roads) Repercussions downstream – Flooding – Pollution discharge Image source: University of Florida. Original image source: University of Florida. 2 03/26/2013 Pollution Point Source – Readily identified source – Contribution greatly lessoned, due to environmental regulations Non-Point Source – Not easily traced to source Pollution Sources – Urban Settings Construction activities Degrading roads/pavement Emissions from motor vehicles Vegetation, which as leaves, grass and other yard debris Litter and trash, including pet wastes Chemicals – Fertilizers – Pesticides – Herbicides Wastewater, including overflow from septic systems Algae Single celled, almost microscopic organism Live in large colonies Not exactly a terrestrial plant – No roots, stems or leaves Performs photosynthesis Similar growth requirements as plants – Nutrients – Light 30,000 species “Good” Algae - Chara Attaches to pond sediments Found 2 – 3’ below surface Indicator of clear water Forms mats when free-floating Helpful to stormwater systems Take care not to kill off Phosphorus is key: – In waters with low levels of P (< 20 micrograms/L) – Filamentous green algae requires high P levels “Good” vs. “Bad” Algae 4 Types – – – – Cyanobacteria – blue-green Chrlorophyta – green Phaephyta – brown Rhodophyta - red “Good” algae – Includes many types of green algae – Indicates a healthy water system “Bad” algae – Includes red, brown and blue-green varieties – System is out of balance Stormwater Pond Best Management Practices (BMP’s) General definition: Methods or techniques found to be the most effective and practical means in achieving an object (such as preventing or minimizing pollution) while making the optimum use of available resources. In terms of stormwater management: Both structural or engineered control devices and systems (e.g. retention ponds) to treat polluted stormwater, as well as operational or procedural practice (e.g. minimizing use of chemical fertilizers and pesticides). 3 03/26/2013 Stormwater Pond Best Management Practices (BMP’s) Keep inflow and outflow structures clear Weed control, including invasive vegetation Shoreline stabilization Pollution prevention - Keep anything other than water from entering the stormwater system Establish a maintenance-free buffer zone Dredging and repair Monitoring BMP’s – Public Acceptance is Key Come to consensus – Serves/benefits all members of a community – Can adversely affect all Prioritize intended uses for ponds – Top priorities – flood prevention and pollution control – Other uses – irrigation, recreation and marketability Create community-wide awareness of the program Explain how individuals can help implement the plan Monitor the program and obtain feedback BMP’s – Dredging Definition: To remove sand, silt, mud, muck, etc. from the bottom of a stormwater pond or other waterbody. Stormwater Pond Restoration Treatments (Buying time before re-dredging) Aeration BMP’s – Dredging Inevitable Expensive Long and complicated permitting process Harmful to fish and wildlife Dredged “muck” is harmful to environment Stormwater Pond Restoration Treatments Aeration Floating Wetland 4 03/26/2013 Stormwater Pond Restoration Treatments Aeration Floating Wetland Grass Carp Stormwater Pond Restoration Treatments Stormwater Pond Restoration Treatments Aeration Floating Wetland Grass Carp Copper Sulfate Dye Restoration Treatments - Aeration Restoration Treatments – Floating Wetland Plastic grid filled with native aquatic plants and anchored in place within the pond Competes with algae for pond nutrients Harvesting of plants, necessary to remove accumulated nutrients Aesthetically pleasing Effective Aeration Floating Wetland Grass Carp Copper Sulfate Oxygenates water Mixes water to prevent stratification Controls accumulation of pond bottom muck Can add 20 – 25 years to life of pond Fountain ≠ Aeration Should be run 24 hours a day Most effective treatment method High cost Restoration Treatments – Grass Carp Biological control – herbivorous fish Sterile – live 10 years “Grazer” – feeds on surface and shallow water plants Not effective in controlling “bad” algae Prefers Hydrilla and Chara Effective on certain types of nuisance plants Low cost 5 03/26/2013 Restoration Treatments – Copper Sulfate pH of water needs to be measured prior to treatment Can cause Oxygen concentrations to drop Can cause fish kills Linked to methylmercury Short-term - Can be effective Long-term - Starts a negative self-feeding cycle Relatively inexpensive Not recommended for low alkalinity or low oxygen ponds Key to Pond Maintenance – Control What Enters the Pond Proper disposal of trash and waste Key to Pond Maintenance – Control What Enters the Pond Proper disposal of trash and waste Appropriate use of pesticides, herbicides and fertilizers Apply fertilizer only when grass is actively growing Restoration Treatments - Dyes Darkens the water Reduces sunlight penetration Limits plant growth Safe for aquatic wildlife Spreads readily Effective Inexpensive Key to Pond Maintenance – Control What Enters the Pond Proper disposal of trash and waste Appropriate use of pesticides, herbicides and fertilizers Key to Pond Maintenance – Control What Enters the Pond Proper disposal of trash and waste Appropriate use of pesticides, herbicides and fertilizers Apply fertilizer only when grass is actively growing Use fertilizer formulations that are at least 50% slow release 6 03/26/2013 Key to Pond Maintenance – Control What Enters the Pond Proper disposal of trash and waste Appropriate use of pesticides, herbicides and fertilizers Apply fertilizer only when grass is actively growing Use fertilizer formulations that are at least 50% slow release Enforce municipal “illegal dumping” ordinances Key to Pond Maintenance – Control What Enters the Pond Proper disposal of trash and waste Appropriate use of pesticides, herbicides and fertilizers Apply fertilizer only when grass is actively growing Use fertilizer formulations that are at least 50% slow release Enforce municipal “illegal dumping” ordinances Post “No littering” signs that include a phone number Periodic street sweeping Buffer Zone Considerations Never grow grass to the edge of pond (or stormwater drain) Don’t mow, fertilize or apply pesticides Don’t apply irrigation (after plants are established) Avoid loose grass clippings Prevent pet wastes from reaching water body Key to Pond Maintenance – Control What Enters the Pond Proper disposal of trash and waste Appropriate use of pesticides, herbicides and fertilizers Apply fertilizer only when grass is actively growing Use fertilizer formulations that are at least 50% slow release Enforce municipal “illegal dumping” ordinances Post “No littering” signs that include a phone number Maintenance-Free Zone Create a low maintenance buffer zone – At least 10 feet wide – Can include low maintenance plants – Remove invasive species Purpose – Natural filter – Attracts wildlife – Prevents erosion Aquascaping Practice of using aquatic and wetland plants to landscape in and around water. Many counties in Florida promote and require Aquascaping of stormwater ponds. Maintenance – Aquascaping, like gardening and landscaping, must be maintained. Image source: Orange County, FL. 7 03/26/2013 Aquascaping - Purpose Aquascaping Pollutant filtration Erosion control Wildlife habitat Invasive plant species control Aesthetic value Image source: University of Florida. Aquascaping – Plants Submersed – grow entirely under water – cannot survive out of water. Bacopa caroliniana, Lemon Bacopa Aquascaping – Plants Floating – float free on the water – rooted in the ground with leaves floating on the surface Nelumbo lutea, American Lotus Determine average water level on a yearly basis Measure maximum depth in the planting areas Start in deepest zone and work toward shore Marginal and transitional plants in buffer zone Aquascaping – Plants Submersed – grow entirely under water and – cannot survive out of water. Ludwigia repens, Red Ludwigia Aquascaping – Plants Floating – float free on the water – rooted in the ground with leaves floating on the surface Nymphaea odorata, Fragrant Waterlily 8 03/26/2013 Aquascaping – Plants Emergent - rooted in the ground – Aquatic plants need to be rooted in the water leaves and flowers project above the water Aquascaping – Emergent Plants Aquatic – need to be rooted in the water – leaves and flowers project above the water Iris virginica, Blue Flag Iris – Canna flaccid, Golden Canna Aquascaping – Emergent Plants Aquatic – need to be rooted in the water – leaves and flowers project above the water Pontederia cordata, Pickerelweed Aquascaping – Emergent Plants Aquatic Short-stemmed marginal plants – low growing bog-type plants that grow well on wet mud or sand Drosera cappillaris, Pink Sundew Aquascaping – Emergent Plants Aquatic – need to be rooted in the water – leaves and flowers project above the water Sagittaria lancifolia, Duck Potato Aquascaping – Emergent Plants Aquatic Short-stemmed marginal plants – low growing bog-type plants that grow well on wet mud or sand Eriocaulon spp., Pipeworts 9 03/26/2013 Aquascaping – Emergent Plants Aquatic Short-stemmed marginal plants Marginal or transitional plants Aquascaping – Emergent Plants Aquatic Short-stemmed marginal plants Marginal or transitional plants – grow on the interface of wetland and upland habitats – prefer changing water levels – grow on the interface of wetland and upland habitats – prefer changing water levels Helianthus angustifolius, Swamp Sunflower Cephalanthus occidentalis, Buttonbush Aquascaping – Emergent Plants Aquascaping – Emergent Plants Aquatic Aquatic Short-stemmed marginal plants Marginal or transitional plants Short-stemmed marginal plants Marginal or transitional plants – grow on the interface of wetland and upland habitats – prefer changing water levels – grow on the interface of wetland and upland habitats – prefer changing water levels Muhlenbergia capillaris, Gulf Muhly Grass Aquascaping – Emergent Plants Aquatic Short-stemmed marginal plants Marginal or transitional plants – grow on the interface of wetland and upland habitats – prefer changing water levels Taxodium distichum, Bald Cypress Zephyranthes atamasco, Rain Lily Retention Ponds In the process of dying Will have to be re-dredged Lifespan: 20 – 25 years Buy time by: – – – – Aeration system Do not grow grass up to water’s edge Establish maintenance-free zone Prevent pollutants from entering 10 03/26/2013 Resources Resources (cont.) Adopt-A-Pond Program, Hillsborough County – http://www.hillsborough.wateratlas.usf.edu/AAP/ IslandWalk Community DVD – Dr. Herb Schuchman, Co-chair, Lake Committee – email: [email protected] Center for Aquatic and Invasive Plants, University of Florida Institute of Food and Agricultural Sciences – http://plants.ifas.ufl.edu/ Stormwater Systems in Your Neighborhood brochure – Southwest Florida Water Management District http://www.swfwmd.state.fl.us/publications/type/all Clemson Cooperative Extension – http://www.clemson.edu/extension/natural_resources/water/stormwater_pon ds/ The Florida-Friendly Landscaping Guide to Plant Selection and Landscape Design – Southwest Florida Water Management District – http://www.swfwmd.state.fl.us/publications/type/all The Florida Yards & Neighborhoods Handbook – Florida-Friendly Landscaping™ – http://fyn.ifas.ufl.edu/publications.htm 11