Municipal Surface Water Supplies.
An excel spreadsheet containing number of surface water intakes per 11-digit watershed, and population served by the supplier operating each intake. Because population figures were repeated for intakes operated by the same supplier, the decision was made to include population figures repeated in different watersheds, and to exclude population figures repeated within a single watershed. The total number of intakes and population served per watershed were summed, and the resulting table joined to a HUC-11 coverage using the watershed ID. Watersheds were then classified as high, medium, or low for number of intakes and population served, separately, as follows:
> 6 intakes = High Intakes
3 - 5 intakes = Medium Intakes
< 3 intakes = Low Intakes
> 50,000 = High Population
5,001 - 50,000 = Medium Population
<= 5000 = Low Population
Watersheds in the High class for either Intakes or Population were assigned a score of 4. Those in the medium class for both Intakes and Population were scored as 3. Those in the low class for one category and the medium for the other were given a score of 2. Those watersheds in the low class for both Intakes and Population were scored as 1. The resulting coverage was converted to a grid, retaining the scores as cell values. The resulting grid was then multiplied by a weight of 4.