Our study developed a methodology to rapidly assess watershed land and to identify parcels critical for water quality protection. Using a Geographic Information System (GIS- ArcView), we inventoried 993 parcels in the Hammonasset watershed (located in south central Connecticut, totaling 13,120 acres), generated parcel maps and associated tables of attributes, and ranked the properties according to hydrologic significance, proximity to protected open space, acreage, and threat of development. The maps and tables facilitate pro-active land protection whether via direct purchase, donation, or through the use of conservation easements.

The first step of the methodology is the compilation of digital information: GIS map layers, orthophotographs, digital elevation maps (DEMs), and United States Geologic Service 7.5 minute topographic maps (USGS topo maps). We obtained this information from town halls, the University of Connecticut’s Map and Geographic Information Center (MAGIC) website, and from the Midstate Regional Planning Agency. For each town in the watershed the following digital information was collected: Parcel Boundaries, Drainage Basins, Hydrography, Land Use, Soils, Surficial Materials, Roads, Future Land Use, Aquifers, and Zoning.

GIS analysis began by delineating the Hammonasset watershed using data provided by the Drainage Basin layer. Next, we identified water features on each parcel using the Hydrography layer, and orthophotographs were examined to identify intermittent streams not depicted on the GIS layers. By combining Land Use, Zoning, and Road layers with orthophotographs, we determined current levels of development and inferred development potential and sedimentation and erosion hazards based on the Soil and Surficial Materials layers. After the initial analysis of map layers, a series of ArcView functions were performed using Query Builder and Map Calculator to generate a comprehensive table associating the physical features of each parcel with its parcel number. Municipal information and whether a parcel was adjacent to existing open space was added to the table manually. This combined all parcel information in the "parcel attribute table," allowing the user to select a parcel on the map and retrieve information regarding its acreage, owner, water features, cover type, assessed value, etc.

After creating the comprehensive attribute table, the Hydrography and Land Use layers were converted into grid format. A series of calculations were performed to generate a composite map of parcels containing features desirable for watershed protection. Through this process a map of parcels greater than 5 acres that contained either water features or forest cover (or both) was obtained. This map coupled with data from orthophotographs and tax assessors’ information provided us with the selection of unweighted, yet important, parcels to be prioritized. Prioritization was based on relative importance for watershed protection. The process required professional judgment; properties had to be ranked individually with respect to one other. This involved weighting the relative advantages of each parcel against one another. Table 1 lists qualities that render a parcel "critical".

Table 1: Important Features of Parcels

FEATURE	SIGNIFICANCE TO WATER QUALITY
Water features (swamps, wetlands, streams, etc.)	Directly protects water source from negative effects of development
Forest cover	Increases infiltration and reduces erosion
Contiguous with existing open space	Creates larger, discrete undeveloped area, which is good for habitat and filtration; Easier for agencies to justify protection
Highly erodable soils	Protects areas prone to erosion and reduces sedimentation
Slope greater than 15%	More susceptible to erosion, especially during construction activities
"Likely' to be developed	Most important to protect first, especially if containing many features listed above

We chose to rank parcels on a scale from 1 to 4. The highest priority parcels were given a rank of 4. Ranking was not as straightforward as "a large parcel with water features and steep slopes receives a rating of 4" because other factors had to be considered, such as whether a parcel had buildings on it, or whether it had the potential to link with other protected lands. Properties were given a high ranking in two situations; one in which the parcel was in "pristine" natural condition, and another in which use of the parcel was actively degrading the watershed, as could be the case with some dairy farms or agriculture. (Our rankings of farms were speculative; further investigation of the effects of specific agricultural practices on water courses would be necessary for proper assessment of harm and subsequent ranking. Such investigation was beyond the scope of this study.)

After ranking all the parcels, a prioritized map of the watershed was generated providing a thumbnail sketch of critical properties. The priority parcels were labeled high, medium, and low with respect to preservation to protect water quality. This final map should be considered a work-in-progress, and should be updated as purchases and subdivisions occur. For instance, if a high priority parcel is acquired and protected, the adjacent parcel may subsequently increase in priority. The rankings are easily changed by editing the ArcView table.

This study describes a simple method of cataloging property in an organization’s operational area. The creation of a prioritized list provides an immediate thumbnail sketch of a parcel’s physical attributes, and the corresponding maps offer visual guides for choosing parcels, preventing scattered land ownership. Our methodology is useful for land use managers and decision-makers who have limited time, and for those organizations low on funding.

We prioritized parcels with regard to their importance for water quality, the main focus of the RWA. Other organizations, however, might very well create lists based on other goals, such as the ability to offer habitat to rare and endangered species or to offer passive recreation. We suggest that all conservation organizations devise their own list of priority parcels, and subsequently exchange lists. Sharing lists will facilitate collaboration on the protection of critical parcels, making evident which parcels are held in common esteem. Organizations would be able to quickly assess which might be most interested in parcels as properties enter the market, and with which to partner in joint purchases.

One potential pitfall to list-sharing might be that a group will hide its true interest in a parcel for fear that it will shoulder the financial and organizational burden of acquisition and maintenance; a parcel might not be protected if each organization expects that another will protect it. We believe that the benefits of having a prioritized list would outweigh these risks.

The maps and attribute tables generated during our twelve-week study period were submitted to the RWA to help prioritize their land acquisition efforts in the Hammonasset watershed. They will be maintained as "active" documents updated as changes in land ownership and development take place. For reasons of confidentiality, however, they cannot be disclosed to the public.