1. Looking beyond 2010… WRTC Meeting May 11, 2006
Offsetting Nutrient Loads in the Face of Urban Growth
WRTC Meeting
May 11, 2006
Condensed from Bay Program Reevaluation Workshop Presentation
September 21, 2005
Thank you
We’ll take a look beyond 2010 & discuss the implications of continued urban growth
Included in our concern is maintaining progress, prevention of backsliding and considering provisions for offsetting new loads
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 offset.
4. Projections of urban development and loads beyond 2010 are needed to estimate the scale of required offsets.
There are five major points to frame today’s discussion
#1 - Urban development is the fastest growing source of nutrients to the Bay
#2 – If wastewater is factored in, urban development contributes more nutrient loads than agriculture
#3 - Maintaining progress and preventing backsliding will require a system to offset the load from new development
#4 - Further analysis will require land use and load projections beyond 2010
#5 - Analysis is needed to determine the nature of an effective offset program
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

3. 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
First, the 2010 land use projection uses a linear extrapolation of population increase with impervious cover increase (1 person/1 unit of land).
We now know this is not true.
Between 1990 and 2000, analysis has shown that while population increased 8%, impervious cover increased by 41%.
“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.

4. 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.
The way we show this graph misrepresents the composite nature of the impact of the urban sector
By not looking at the composite urban picture, many people suggest that the next slide is actually good for water quality …

5. Bring on development to reduce agricultural runoff

6. Urban Development May Impact Restoration Progress:
Flow-Adjusted Trend in Total Nitrogen
DRAFT
USGS has recently published some troubling data
Some monitoring evidence showing that in at least one developing areas, there has been an uptick in loads for both nitrogen and phosphorus
We appear to be backsliding there.

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.
Therefore, rather than just focusing on the sectors that are dominant in 2010, we may want to look at the sectors that are impacted by population growth more comprehensively
All of a sudden, that puts impacts due to development …

8. 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 Alternative Growth Scenarios (Urban, Wastewater, Agriculture, Forest)
January 2007 – WS Model Runs of 3-5 alternative scenarios
Foundation for offsets analysis
Finally, our recommendations for the next steps and a rough timetable
Diana, it’s your turn to take it from here