A GIS-Based Model to Identify Sensitive Water Resource Properties

in Need of Protection

2009 Watershed Science and Technical Conference

September 14 & 15, West Point, NY

Jen ZhangWatershed Protection Specialist

New Jersey Water Supply Authority(NJWSA)

NJWSA Water Supply System

Independent State Authority – 1981

Operates state owned water supply facilities

Round ValleySpruce RunDelaware & Raritan CanalRaritan System Manasquan

Location of NJWSA Water Supply Systems

Source Water Protection Program in NJWSA

• Source Water Protection (SWP) has long been recognized as one of the most effective means for ensuring long-term viability of water supply and maintenance of water quality.

• The Authority created and instituted a comprehensive SWP program including the creation of a Watershed Protection Unit in 1999 and a Land and Resource Preservation Program in 2002.

• The Watershed Protection Unit (WPU) was created to improve the protection of water resources and to develop and implement projects that improve protection of water supply for the Authority and its customers.

• The Land and Resource Preservation Program was designed to identify, acquire, and manage critical watershed parcels toward protection of water supply.

• GIS has been heavily involved since the start of the program to help identify critical properties for protection.

Acquisition Approach• Focus – preservation

of contiguous lands• Strategy – link land

acquisition and zoning benefits

• NJWSA customers support through water supply rates

• Partner with State & local governments, land trusts

Target Areas

• 6,900 acres (240 parcels) in 6 project areas targeted for preservation back in 2002 only in five municipalities

• Strategy now extends outside of original target areas

• The acquisition target area extends from its original five to forty municipalities

• The target area extends from original 6,900 acres to a total of 185,500 acres

• Focus on: Sensitive Water Resource Area

Location of Target Area

2,700 acres preserved to date

(2009)

1,119 acres in active

negotiations

The GIS Model Project Background

The GIS Model Constrains• This project focused on water resource protection, it

does not address all land conservation goals.• The GIS model focused on remaining lands instead of

the existing preserved (open space and farmland) or developed lands.

• Use readily available GIS data, was limited by data availability and how current the data is (eg. 2002 LU/LC)

Acquire Sensitive Water Resources

• Stream corridors• Headwaters• Wetlands• Flood hazard areas• Critical habitats• Riparian forests• Prime ground water recharge and aquifer recharge

areas• Highly erodible soils ……

The Database Model and Layers

Class Values WeightK-Factor 0.0 - 0.2 (low) 10

0.2 - 0.4 (medium) 200.4 - 0.6 (high) 30

Land Use Water 0

Wetlands 0Forest 10Urban 20Agriculture 30Barren Land 30

Slopes 0 -- 5% 5

5 -- 10% 1010 -- 15% 1515 - 20% 2020 - 30% 3030 - 50% 40>50% 50

Class Values Erosion Susceptibility

Erosion Susceptibility

Theme

0 Not erodible land1 -- 10000 Low - medium low10001 -- 20000 Medium - medium high>20001 High - extremely high

The Composite Map of Water Resource Area

The Composite Map

The Individual Water Resource Area –Riparian Area

Riparian Area

The Individual Water Resource Area –Highly Erodible Soils

Property Analysis

The property analysis can show -

• The % of water resource area on each property (all the water resource areas were weighted equally and grouped into a composite critical area)

• The type and the location of water resource area on each property.

Property Boundary Overlay with Sensitive Water Resource Area

% of Properties in Sensitive Water Resource Area

Application of this GIS Model• Rank properties by their % included in water resource area• Rank properties by property size• Check what water resource environmental features located

in each property and where• Assess and evaluate potential properties for future

acquisition• Avoid isolated open space – consider proximity to existing

preserved open space• Use the findings from this project to assist in soliciting state

funds• Can lead to improvements to municipal ordinances, master

plans, environmental resource inventories, zoning density, open space preservation plans, etc

• All potential properties will be first evaluated through this database to determine the number of criteria present

• If a property ranks highly enough, a second level of evaluation will be applied. This second tier will be a case-by-case critical review.

• All the criteria are weighted equally in this database. Further scoring might be added based on project requirement.

Application of the GIS Model - Continued

A comprehensive approach that relies on strong partnerships at all levels

www.njwsa.org/wpu www.raritanbasin.org Tel: 908-685-0315

Open Space Acquisition in the Raritan Basin