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Looking beyond 2010… Offsetting Nutrient Loads in the Face of Urban Growth

Looking beyond 2010… Offsetting Nutrient Loads in the Face of Urban Growth. Local Government Advisory Committee December 7, 2005. Originally Presented at the CBP Reevaluation Workshop September 21, 2005. Ted Graham, Chair Land, Growth, and Stewardship Subcommittee. Major Points.

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Looking beyond 2010… Offsetting Nutrient Loads in the Face of Urban Growth

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  1. Looking beyond 2010… Offsetting Nutrient Loads in the Face of Urban Growth Local Government Advisory Committee December 7, 2005 Originally Presented at the CBP Reevaluation Workshop September 21, 2005 Ted Graham, Chair Land, Growth, and Stewardship Subcommittee

  2. 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 somehow offset – critical to prevent backsliding. 4. Projections of urban development and loads beyond 2010 are needed to estimate the magnitude of future loads and the scale of required offsets. 5. Multifaceted dialogue is needed to determine what will constitute an appropriate and effective offset program.

  3. Upcoming Tasks • LGSS Lead Responsibility (w/ NSC & LGAC) • Project future land use through 2030 • Project population through 2030 • Allocate land use through new modeling tools • WSM also needs wastewater, agriculture & forest projections • Development of Alternative Future Scenarios • Initiate “offset” discussion • Related Activities • WSM Model Runs (NSC)

  4. Housing Trends 1960 – 1990 (census block groups) Total Housing Units 1960 Total Housing Units 1970 Total Housing Units 1980 Total Housing Units 1990 Historical Block Group Analysis courtesy of D. Theobald, 2001

  5. Development “Hot Spots” (1990 – 2000)

  6. Nitrogen Loads to the Chesapeake Bay Watershed (Total Loads – Overall Program Focus and Overall Growth) Agriculture Urban/Suburban

  7. 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.

  8. 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.

  9. Development Pressure in the Chesapeake Bay Watershed (1990 – 2000)

  10. 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.

  11. Urban Development May Impact Restoration Progress: Flow-Adjusted Trend in Total Nitrogen DRAFT

  12. 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.

  13. Nitrogen Loads to the Chesapeake Bay Watershed (Total Loads – Overall Program Focus and Overall Growth)

  14. Forecasting to 2030 • 20 Years is an accepted planning horizon for: • Capital investments (STP) • Comprehensive Planning • Population projections • Provides lead time to develop cap management strategy, e.g., offsets & trading • Ongoing growth modeling work is targeting 2030.

  15. LGSS as Lead . . . • Most of the change is related to where and how the watershed is growing. • LGSS is working on 2 types of growth models that STAC will peer review this winter. • Best suited to understanding the factors that impact decisions on growth patterns.

  16. SLEUTH model calibration mapped modeled The greater Baltimore – Washington DC metropolitan area, circa 2000 Jantz C. A., Goetz S. J. & Shelley M. A. (2003) Using the SLEUTH urban growth model to simulate the land use impacts of policy scenarios in the Baltimore-Washington metropolitan region.Environment and Planning (B) 31(2): 251-271.

  17. . . . In Partnership with NSC . . . • Tributary Strategy Workgroup has vital experience needed to complete a new land use. • NSC has experience with Agricultural projections and the Ag Census . . . Modeling . . . • Coordination with Phase V watershed model.

  18. . . . And with LGAC . . . • Local government input is vital • LGAC is essentially the only place in the CBP where officials come together with explicit land use experience

  19. Recapitulation 1. LGSS tasked with preparing 2030 development projections. 2. LGSS tasked with revising the growth allocation models to drive the Phase V Watershed Model. 3. LGSS and NSC 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: • January 17, 2006, worksession covering these topics. • By December 2006, present an interim report to the IC. • By June 2007, present a final report to the IC, including any recommendations for follow on work.

  20. Activity Completion Date Proposed Timeline STAC Peer review of Urban Growth Models 2006 Development of alternative future scenarios; Development of agricultural forecasts; Development of offset strategy concepts June 2006 Coupling agricultural and urban forecasts; Simulation of alternative future scenarios; September 2006 Phase V model runs using future scenarios Winter 2006 Incorporation of offset strategy in Tributary Strategies June 2007

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