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This presentation highlights the urgent need to offset nutrient loads from urban development in order to achieve and maintain water quality in the Chesapeake Bay. It emphasizes the growing contribution of urban development, including wastewater, to nutrient loads and the importance of projections for future urban growth. Recommendations are provided to prepare development projections, revise growth allocation models, estimate nutrient projections, and define an effective urban development offset program.
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Looking beyond 2010… Offsetting Nutrient Loads in the Face of Urban Growth WRTC Meeting May 11, 2006 Condensed from Bay Program Reevaluation Workshop Presentation September 21, 2005 Ted Graham, Chair Land, Growth, and Stewardship Subcommittee
Major Points 1. Urban development is the fastest growing source of nutrients to the Bay. 2. Urban development, including wastewater, contributes more nutrients to the Bay than agriculture. 3. The C2K goal to achieve and maintain water quality can only be met if new urban loads are offset. 4. Projections of urban development and loads beyond 2010 are needed to estimate the scale of required offsets. 5. Analysis is needed to determine what constitutes an effective offset program. 6. COG member/WRTC input is warranted here, both for wastewater & urban stormwater sectors
Forecasting Future Land Use • Between 1990 and 2000: • population increased 8% • impervious surfaces increased 41% • Because: • Smaller family size • Bigger houses • Larger commercial and retail parking lots “If recent trends continue, the area of developed land in the (Bay) watershed will increase by more than 60% by 2030” ~ “Chesapeake Futures: Choices for the 21st Century”, STAC 2003.
Nitrogen Loads to the Chesapeake Bay Watershed (Total Loads – Overall Program Focus Excluding Overall Growth) Total loads to the Chesapeake Bay in million pounds per year answer questions concerning overall program focus. When “urban/suburban” total loads consider only the stormwater runoff from the land area, the question of “urban/suburban” loads versus agricultural loads treats population as a given and speaks to land conversion. In this case for nitrogen, total agricultural loads exceed urban/suburban runoff – looking at the scale of the Chesapeake Bay watershed as a whole.
Urban Development May Impact Restoration Progress: Flow-Adjusted Trend in Total Nitrogen DRAFT
Nitrogen Loads to the Chesapeake Bay Watershed (Total Loads – Overall Program Focus Excluding Overall Growth) Total loads to the Chesapeake Bay in million pounds per year answer questions concerning overall program focus. When “urban/suburban” total loads consider only the stormwater runoff from the land area, the question of “urban/suburban” loads versus agricultural loads treats population as a given and speaks to land conversion. In this case for nitrogen, total agricultural loads exceed urban/suburban runoff – looking at the scale of the Chesapeake Bay watershed as a whole.
Recommendations 1. LGSS be tasked with preparing 2030 development projections. 2. LGSS be tasked with revising the growth allocation models to drive the Phase V Watershed Model. 3. LGSS and NSC be tasked with estimating 2030 nutrient projections by major watershed. 4. LGSS and NSC, in consultation with LGAC, be tasked with defining the framework of an urban development offset program. TIMING: • July 17, 2006 – 2030 Land Use Projection Worksession • October 2006 – September 2007 - Alternative Growth Scenarios (Urban, Wastewater, Agriculture, Forest) • January 2007 – WS Model Runs of 3-5 alternative scenarios • Foundation for offsets analysis
