residential stormwater quality evaluation...avg. property value (just value 2014) $170,137 $109,831...
TRANSCRIPT
RESIDENTIAL STORMWATER QUALITY EVALUATION
RESIDENTIAL STORMWATER QUALITY EVALUATION
TAMPA BAY ESTUARY PROGRAM
December 11, 2014
Water Quality Results & RecommendationsWater Quality Results & Recommendations
OVERVIEW
• Study Goal• Brief Review Methods• Nutrient Inputs: Social Data and Soil Results
(review)• Nutrient Outputs: Environmental Data• Conclusions• Recommendations
Fertilizer Ordinance is passed with seasonal sales restriction in one County (Pinellas)
Is there a difference in ordinance awareness among residents living in sales-restricted County?
Is there a difference in fertilizing practices among residents living in sales-restricted County?
Is there a difference in N pollutant loads among residents living in sales-restricted County?
STUDY OBJECTIVES
1. Measure and compare average inputs of N in lbs/area
2. Measure and compare residential landscape management practices and knowledge
3. Estimate residential fertilizer inputs to the community nutrient budget
4. Measure nutrient concentrations in stormwater runoff and pond water throughout the year
WHICH COMMUNITIES?
• Landscape management practices (Mixed)
• Biological, geographic, and geological features
• Drainage areas and general hydrology
• HOA presence • Housing demographics
(house age, lot size, density)• Absence of golf course• No reuse water used for
irrigation• No septic onsite
Control Variables
COMMUNITY CHARACTERISTICSJurisdiction Hillsborough Manatee Pinellas Pinellas
Location Code H101 M101 P201 P202
Total acreage 58.70 45.73 17.65 102.90
Have HOA Y Y Y Y
Year Built (mean age) 2002 2003 2003 1984
Avg. Property Value (Just Value 2014)
$170,137 $109,831 $313,259 $176,0721
Total Pervious (aerials) 41.96 33.02 8.66 53.52
Golf course presence No No No No
HOA self-maintained No No No No
Average lot size 0.37 0.23 0.18 0.25
Average built area 2596 1738 2566 2228
Irrigation SourceCommunity
Well City City City
SOCIAL DATA COLLECTION
1. Representative Countywide Telephone Survey (n=835)
2. Community Level Homeowner Interviews (n=81)
3. Community Level Professional Interviews (n=6 of 31 attempted)
ENVIRONMENTAL SAMPLING
1. 10 soil samples from each community (total 40)2. 3 irrigation samples from each community (total
12)3. 9-11 storm events collected from each comunity
(total 40)4. 18 surface water sampling events within
community stormwater ponds or retention areas(total 72)
5. Standard Laboratory Analysis of pond/stormwater and soil extracts
6. Isotope Analysis (15N and 18O) of soil extracts and selected pond/stormwater samples (15N and 18O)
FERTILIZER USE FREQUENCY
County-wide Telephone SurveyCommunity Homeowner
InterviewsCounty n Mean Site n Mean
Hillsborough* 253 2.46 H101* 23 5.96Manatee 252 2.17 M101* 12 2.17
Pinellas* 223 1.73P201 11 3.82
P202* 15 3.67Total 728 2.14 Total 61 4.26
* ANOVA with Tukey post-hoc significant difference at p < .05
MONTHS FERTILIZER USED (%)
Important to note that we didn’t investigate WHAT was being applied
County n Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Hillsborough 167 20 22 33 27 20 19 16 16 22 26 19 17
Pinellas 133 11 13 29 20 17 15 13 11 21 22 11 13
Manatee 179 14 14 26 21 15 15 15 11 17 19 20 13
ORDINANCE AWARENESSHillsborough Pinellas Manatee
Do the ordinances…Restrict the use of lawn fertilizer during the rainy season? 75% 75% 66%Restrict the sale of lawn fertilizer during certain months?* 62% 79% 51%Reduce the amount of phosphorous (“P”) allowed in lawn fertilizer? 65% 77% 69%Reduce the amount of nitrogen (“N”) allowed in lawn fertilizer? 58% 62% 66%Require training for professional landscaping companies? 57% 52% 45%N = 188 * p < .001
Pinellas County residents were significantly more likely (43%, p < .0001) to respond that they had heard about government regulations concerning residential fertilizer use than either Hillsborough or Manatee (both 26%).
NITROGEN INPUTS FROM LANDSCAPE MANAGEMENT - ESTIMATES
Community
ProfessionalFertilized
(Acres)
Owner Fertilized
(Acres)
Not Fertilized
(Acres)
Pervious Area
(Acres)N Input
(Lbs)N Inputs
(Lbs/acre)H101 28.53 13.43 0.00 41.96 5496.3 93.6M101 5.45 11.06 16.51 33.02 1775.2 38.8P201 2.25 3.90 2.51 8.66 676.0 38.3P202 16.06 24.08 13.38 53.52 4504.4 43.8
SOILS BY LOCATIONAnalyte H101 P201 P202 M101
NOx-N Mean (mg/kg)
9.1 (2.6) 11.9 (5.8) 6.2 (2.9) 5.9 (2.4)
NH4 Mean (mg/kg)
2.4 (1.4) 2.8 (0.9) 2.1 (0.7) 2.5 (1.4)
*Org. Matter (%) 4.5 (1.12) 6.5 (2.2) 4.3 (0.9) 2.6 (0.6)
*TKN Mean (mg/kg)
1296.2 (356) 1657.3 (499.9) 1395.7 (251.8) 793.6 (181.7)
**P Mean (mg/kg)
49.6 (14.3) 55.9(22.1) 54.5 (30.3)325.900 (514.87)
*EC Mean (ds/m)
0.1 (<0.1) 0.2 (<0.1) 0.1 (<0.1) 0.1 (<0.1)
*pH Mean 6.5 (0.5) 7.4 (0.3) 6.3 (0.6) 6.7 (0.6)
House Age Mean (yrs)
12 11 30 11
MONTHLY RAINFALL TOTALS AT H101
Dry Season (Oct-May): 18.91”Wet Season (Jun-Sep): 37.46”Modified Wet Season (Jul-Oct): 39.61”
H101 TOTAL NITROGEN CONCENTRATIONS
MONTHLY RAINFALL TOTALS AT M101
Dry Season (Oct-May): 21.94”Wet Season (Jun-Sep): 34.02”Modified Wet Season (Jul-Oct): 42.39”
M101 TOTAL NITROGEN CONCENTRATIONS
MONTHLY RAINFALL TOTALS AT P201
Dry Season (Oct-May): 18.05”Wet Season (Jun-Sep): 25.94”Modified Wet Season (Jul-Oct): 32.3”
P201 TOTAL NITROGEN CONCENTRATIONS
MONTHLY RAINFALL TOTALS AT P202
Dry Season (Oct-May): 27.19”Wet Season (Jun-Sep): 32.35”Modified Wet Season (Jul-Oct): 41.89”
P202 TOTAL NITROGEN CONCENTRATIONS
ANNUAL LOAD ESTIMATES
Load Estimate = runoff volume * EMC (concentration)* conversion factor *treatment reduction
CommunityMean TN
(mg/l)
Runoff Volume
(1000 m3/yr)
TN Load
(lbs/yr)
TN Load by Area
(lbs/acre)
H101 1.76 72.60 196.99 4.89
M101 1.39 67.05 143.41 4.22
P201 1.45 28.48 63.64 3.48
P202 1.76 17.79 48.34 3.66
SOIL ISOTOPESSoil Samples
Awareness is significantly higher in Pinellas County
Fertilizer ordinance is effectively changing behavior: residents use less fertilizer in Pinellas County
Caveat: no pre-ordinance behavior data available
Water quality concentrations in stormwater do not yet show a clear improvement due to intervention
Estimated TN loads appear to be highest in communities with highest use of fertilizer and lower in areas with seasonal sales restriction
Lag time between social Intervention to change behavior to visible water quality improvements
Nitrogen can be retained in soils for decades and released slowly over time (Sebilo et al. 2013)
CONCLUSIONS
• Evidence of fertilizer use: peaks TN, isotopic signatures of stormwater, soil isotopes
• N input estimates highest for H101 lawns (93.6 Lbs/acre)• Coincides with highest: fertilizer frequency, % professionals &
estimated TN output loads (4.9 lbs/acre)• Professionals might be applying same N annually, just not in
summer – limited data• Professionals travel to multiple jurisdictions – City of Tampa
and Hillsborough same application?• Limited timeframe of the study, difficult to confidently
establish the final link between a change in behavior and the long-term environmental benefit
STUDY DESIGN RECOMMENDATIONS
• Further in situ research is needed at the landscape scale• In situ experiments to evaluate before/after interventions• Intervention study controlling application timing/amount• Use an enriched fertilizer and trace it through a subdivision• Measure isotopic signatures of the rainfall for comparison
with stormwater signature• Obtain N and O isotopic information• Need for community-level socio-demographics and
behaviors studies to compare differences in behaviors over time in treatment vs control groups.
• Trend testing required multiple years of data, preferentially >10 yrs.
ParameterH101 M101 P201 P202
Pond Storm Pond Storm Pond Storm Pond Storm
Total Nitrogen 23 64 32 54 28 85 22 56
Total Inorganic Nitrogen 35 26 102 74 61 31 139 54
Total Phosphorus 42 54 243 167 139 143 38 139
POWER TESTING RESULTS
Note: Minimum Sample Size Required to Detect a 20% Reduction in Mean Parameter for Pond and Stormwater in the Four Communities. Estimates based on a one-sample T-test and not a seasonal trend test.