Transcript Water Quality Restoration for Coastal Subdivision

Water Quality Restoration for
Coastal Subdivision
Retention Ponds
Lorimar Serrano
Marie DeLorenzo
College of Charleston, SC
Background Information
• Storm water retention ponds
• Used as “Best Management Practices” (BMPs) in
residential & commercial developments
• Control flooding
• Settle out contaminants
• Aesthetic and recreational uses
Why care about retention ponds?
• Water quality problems in storm water ponds
– Water eutrophication
• algal blooms, algal toxins, water discoloration, bad
odor
– High contaminant concentrations
– High fecal coliform bacteria levels
Lake Edmonds
• 11 acre fresh water lake
• drainage area = 107 acres (300 homes)
• Lake’s importance:
• overflow into
Kushiwah Creek
• aesthetic value
• wildlife habitat
• recreational boating
• fishing
• model for retention pond
management
Methodology
• Parameters Measured
– Water quality (DO, temp., pH, turbidity,
salinity, conductivity)
– Nutrients (NH4+, NO2-, NO3-, PO43-) (mg/L)
– Chlorophyll a (µg/L)
– HABs (cells counts)
– Algal toxins (microcystin [µg/L])
– Fecal coliform bacteria (CFU/100mL) &
antibiotic resistance (E. coli)
– Pesticides [µg/L]
• Atrazine & 2,4-D (Herbicides)
• Chlorothalonil (Fungicide)
• Chlorpyrifos (Insecticide)
Fecal Coliform Bacteria
FCB (CFU/100mL)
conc. (CFU/100mL)
FCB
700.00
600.00
SC DHEC Standards:
Recreational uses
500.00
400.00
300.00
200.00
100.00
0.00
May-04 Jun-04 Jul-04 Aug-04 Sep-04 Oct-04 Nov-04 Dec-04 Jan-05 Feb-05 Mar-05 Apr-05 May-05 Jun-05
EPA water quality standards for lakes
9/9/04
9/2/04
8/26/04
8/19/04
8/12/04
8/5/04
7/29/04
7/22/04
7/15/04
7/8/04
0.10
0.00
7/1/04
0.20
6/24/04
0.40
0.30
6/17/04
0.50
6/10/04
0.60
6/3/04
0.80
0.70
Phosphate conc. (mg/L)
0.90
5/27/04
8/12/04
8/5/04
7/29/04
7/22/04
7/15/04
7/8/04
7/1/04
6/24/04
6/17/04
6/10/04
6/3/04
5/27/04
Total nitrogen conc. (mg/L)
Nutrient Levels
1.00
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
Atrazine Levels
0.2
Atrazine conc. (ug/L)
Atrazine conc. (ug/L)
0.18
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
Jun-04 Jul-04 Aug-04 Sep-04 Oct-04 Nov-04 Dec-04 Jan-05 Feb-05 Mar-05 Apr-05 May-05 Jun-05
2,4-D Levels
2.5
2,4-D conc. (ug/L)
2,4-D conc.(ug/L)
2
1.5
1
0.5
0
Jun-04 Jul-04 Aug-04 Sep-04 Oct-04 Nov-04 Dec-04 Jan-05 Feb-05 Mar-05 Apr-05 May-05 Jun-05
Anabaena sp. Density
30000
Bloom density
25000
# cells/mL
20000
15000
10000
5000
0
Jun-04 Jul-04 Aug-04 Sep-04 Oct-04 Nov-04 Dec-04 Jan-05 Feb-05 Mar-05 Apr-05 May-05 Jun-05
Microcystis sp. Density
12000
10000
Bloom density
# cells/mL
8000
6000
4000
2000
0
Jun-04
Jul-04
Aug-04 Sep-04
Oct-04
Nov-04 Dec-04
Jan-05
Feb-05 Mar-05
Apr-05
May-05
Residents Survey
• A total of 45 residences in the Lake Edmonds
Homeowners Association were surveyed regarding
land use practices that may influence water quality
• Including: pet waste management, pesticide
applications, pond uses, and homeowner interest in
the pond’s water quality.
66.7% back !!!
Survey Results
• Pet Waste Management
– 75% of dogs & cats were reported as being kept either outdoor or
indoor/outdoor
– Only 9% of homeowners pick up pet waste daily
• Fertilizer Application
– 29% of homeowners apply fertilizer to their lawns
– 68% apply fertilizer 2 or more times per year
• Pesticide Application
–
–
–
–
73% of homeowners apply herbicides to their lawns
83% apply insecticides to their lawns
33% apply fungicides to their lawns
Majority of respondents make 2 or more applications of each pesticide
class per year
Survey Results (cont’d)
• Lake uses
– boating activities
73.68%
– fishing activities
63.16%
• Observed algal blooms
76.67%
• Established vegetative buffer in lawns
10.71%
• Willing to install buffer
68.96%
• Willing to change practices
94.74%
Conclusions
• Water quality problems were detected in the model
retention pond, Lake Edmonds:
– high fecal coliform bacteria levels
– high phosphate concentration
– harmful algal bloom development
– persistent herbicide concentration
• Residential lawn care practices such as the use of fertilizers
and pesticides are affecting the water quality of this
retention pond.
• Pet waste left on lawns may increase fecal coliform
bacteria levels in the lake (runoff with rainfall).
Recommendations
• Some examples of the practices we recommend are:
– Lawn care product recommendations
• lower chemical and nutrient content products
• organic and biodegradable products
• use of the product as directed
– Collection of pet waste from yard and deposit in trash
– Grow plants on the edges between the yards and the
retention pond (vegetative buffer installation)
– Proper disposal of lawn clippings (avoid deposition into
the pond)
http://edisto.cofc.edu/~lserrano/