Future of the Big Darby Future of the Big Darby WatershedWatershed
Steven Gordon
December, 2001
Where are we going?Where are we going?
Current status of stream healthHow development trends will impact itPreserving the quality
– What do we need to do?– How can we get there?
The Good NewsThe Good News
The Big Darby is still a very high quality stream
Data show continued good health in most areas
We have an opportunity to keep it that way
IBI Status Before 1995# Very Poor# Poor# Good# Very Good# Excellent
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IBI Status Since 1995# Very Poor# Poor# Good# Very Good# Excellent
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IBI Status Since 1995
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IBI Status Before 1995
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Status of Fish Communityin Big Darby Watershed since 1989
Impacts of TrendsImpacts of Trends
Noticed that there are several problem areas where deterioration of quality has occurred
What is this related to?How might it change in the future?
Model of IBI in ECBPModel of IBI in ECBP
Eastern Cornbelt Plains Ecoregion
Major Differences Among Major Differences Among WatershedsWatersheds
Differences in habitat quality– Measured by components of QHEI (Qualitative
Habitat Evaluation Index)– Reflect changes in riparian zone quality
Differences in point source pollutionDifferences in land use/non-point source
pollution– Urban land use a key
Web-Based ToolsWeb-Based Tools
Http://tycho.cfm.ohio-state.eduHow does this fit with current trends?
– Analysis done by my students last Spring– Study sponsored by the Darby Creek Association
Urban growth in the basin is substantialA reasonable forecast shows major
additional growth
Predicted IBI with Increases in Urban Area and decreased Pool and Substrate
25
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Obs 10 20 30 40 50
Years
IBI
Sco
re Point 1Point 2Point 3Point 4Point 5Point 6
Growth Rate AssumptionsGrowth Rate Assumptions
Growth rate (not absolute number of persons) was held constant with the following assumptions:– Extremely high growth rate areas would ‘fill
up’ with people and growth will decline– Areas adjacent to high growth regions will have
an increased rate of growth– No growth controls are in place in order to
restrict development anywhere in the watershed
Rates of Population ChangeRates of Population Change
Population Change– Forecasting model
based on population rates of change from 1990 to 2000
– Rates of change varied from -31% to 211%, but most between -2% and 40%
Population Growth from 1990 to 2000
5% growth and below5 to 20%20 to 50%51 to 80%80% and above
Growth Rate AssumptionsGrowth Rate Assumptions
Rates of change that were significantly high (80% to 211%) were halved because of high growth and only moderate projected county growth by the ODOD
Tracts within Counties with high anticipated growth were increased (12.5% to 25% based on ODOD data) depending on adjacency to historically high growth tracts
ResultsResultsPopulation Growth from 1990 to 2000
5% growth and below5 to 20%20 to 50%51 to 80%80% and above
Population Growth from 2000 to 2010
5% growth and below5 to 20%20 to 50%51 to 80%80% and above
Results ContinuedResults ContinuedPopulation Growth from 2000 to 2010
5% growth and below5 to 20%20 to 50%51 to 80%80% and above
Population Growth from 2010 to 2020
5% growth and below5 to 20%20 to 50%51 to 80%80% and above
Comparison with ModelComparison with Model
Model forecast about a 25% growth with lower base
Population forecast pushes rates to 50% for some tracts
Will accelerate deterioration in growth areasProbably have a time-scale of 10-15 years
unless something changes
What needs to be done?What needs to be done?
Action by all communities– From cities to townships to counties– From farmers to residents to developers
A combination of approaches– Protect and improve the riparian zone– Best management practices for all uses for all
areas– Reduction in total growth
Consequences of InactionConsequences of Inaction
Continuing decline of stream quality– Loss of communities– Increased flooding
Loss of prime farmland– Loss of agricultural communities/mix– Loss of open space
Increases in congestion and other urban problems
Possible ActionsPossible Actions
Riparian zone protectionBMP controls in zoning and subdivisionStrict enforcementConservation easements or other land
banking techniques
How do we get there?How do we get there?