Presentation discusses "source reduction" for stormwater management.

1. Biogeochemical Perspectives on Stormwater Management Larry Baker Water Resources Center and WaterThink, LLC

4. Typical removal efficiencies for structural BMPs Source: Weiss et al., 2007 ±26 42 ±25 68 Wetlands ±31 46 ±14 85 Sand filters ±11 72 ±23 85 Bioretention ±23 53 ±32 65 Wet basins ±15 25 ±28 53 Dry extended ponds CV, % Ave. % removal CV, % Ave. % Removal Sediment Phosphorus Type

5. Pollution production Gas loss: CO 2 (decomposition) N 2 (denitrification) VOCs Sedimentation Plant debris Adsorption Remaining pollutants- Soluble P, coliforms, salt, suspended solids Sediment Processes in a stormwater pond or wetland Water Plant uptake N, P, metals Algae growth Recycled Sediment accumulation P recycling Toxics?

6. Pollution production Processes in infiltration BMPs Gas loss: CO 2 , N 2 , VOCs Aquifer Filtration Adsorption Precipitation Soil Nitrate Chloride Clogging Metal accumulation Saturation of adsorption sites

7. End-pipe-BMPs Detention basins Wet ponds Infiltrations basins Wetlands Level 2: Sources from landscapes to streets Level 1: Sources to watershed Level 3: Source from streets to storm sewer Pollutant mass balances: System boundaries Streets are not a source of pollution but a conduit for pollution

8. Level 1 analysis: Effect of lawn P fertilizer restriction Conditions: 5 km 2 residential neighborhood, 0.5 ha lot size, 20% impervious area on lot; 80% pervious area fertilized; 1 dog/house; irrigation. Updated from Baker and Brezonik, 2007 using MN Ag 2006. Before MN P fertilizer ban After MN P fertilizer ban 23% reduction 100 3,984 - Total 2 125 0.25 kg/ha-yr Deposition 2 169 0.3 mg P/L; 0.2 m/yr Irrigation 23 1,770 1.2 kg/dog-yr Dogs 73 1,920 7.5 kg/ha-yr Fertilizer % total, kg/yr Input rate Source 100 3,064 6 125 8 169 86 1,770 0 1,000 % total, kg/yr

9. Level 2 analysis: Inputs from boulevard trees to streets Example: maple trees (based on UFORE model) DBH measurement

10. Level 2 analysis (cont’d): Lawn runoff to street Source: Barten (1994) For comparison: Raw sewage P = 5 mg/L SS = 200 mg/L Eutrophic lake: P = 0.05 mg/L

11. Soil P level vs. dissolved P in runoff from turf (left) and bare soil (right) Soldat et al., 2008 Water, Air, Soil Poll.

13. Growing turf Soil inorganic P Soil organic P Fertilizer P Runoff soluble P Runoff particulate P Exported clippings Mowed grass Leaching Integrating biophysical and social aspects of lawns to reduce soluble P in runoff Baker, Wilson, Fulton, and Horgan, Cities and the Environment , 2008. Lawn P cycle

14. 3 or more fertilizer applications,+ mulching Steep slope, low infiltration soil Nowak disproportionality concept applied to lawns Nowak et al., 2006 Society and Natural Resources High nutrient export Site design Site management

16. 2. Tailor messages to homeowner types (social dimension) “ Casual” “ Perfectionist”

17. Adaptive management for road salt

18. Relationship between % impervious surface and average stream chloride Sander, Novotny, Mohseni, and Stefan, 2008

19. Event analyzed by team - Weather - Pavement conditions - Stream chloride Road crews add salt for snow/ice event. Salt quantities recorded Sensor network records specific conductance; temperature Recommendations summarized; transmitted to road crews Adaptive management schematic dialogue

21. Mississippi + Minnesota Rivers Inflow 16.86 Outflow 17.99 Wastewater 0.41 Withdrawal 0.18 Groundwater pumping 0.46 Recharge 0.46 (assumed) Evaporation 1.37 Precipitation 2.42 Runoff 0.82 Will stormwater management alter the Twin Cites hydrologic balance?