The classification system is hierarchical with Tier 1 at the top of the list and Tier 6 at the bottom. The assignment of Tier protection values (1-6) has been done so that river or lake segments are assigned the highest protection (Tier) value if they meet that Tier’s criteria. Accordingly, river or lake frontage meeting Tier 1 criteria and also meeting Tier 2 or other criteria has been assigned a final Tier value = 1 (its highest level of protection). This order of precedence (1 over 2, 2 over 3, etc) results in no overlap between Tier protection classes (no double counting) in order to better estimate protected frontage as a percentage of all frontage in the watershed.
Tier 1 and 2: The two primary datasets for Tier 1 and Tier 2 analysis is the Conservation polygon shapefile (provided by NH GRANIT) and the National Hydrography Dataset provided by UNH, edited by DES. The method for generating the conservation lands dataset was a combination of converting vector data to raster and employing Spatial Analyst to identify segments whose buffers would intersect conservation lands. Conservation land parcels with no Primary Protection Type (PPTYPE field is NULL) were excluded from this analysis (see Known Issues below) and the stream segments for these parcels would be subject to Tier 3 or higher analysis.
NOTE 1: Most common error within Tier 1 and 2 coding was misclassifications of short stream segments to Tier 6 within conservation lands or coding of short segments outside conservation lands boundaries as Tier 1. To correct all Tier 6 records were isolated and an overlay analysis was used to identify which stream segments intersected the conservation land polygon (excluding parcels with no PPTYPE listed). The selected stream segments within conservation land parcels coded as Tier = 6 (no protection) were corrected from Tier 6 to Tier 1. Those short segments extending beyond the conservation land boundaries remain in the data as errors and may be manually corrected or further geoprocessed to correct.
Tier 3 (CSPA): Tier 3 includes rivers with a stream order of 4 or greater, or great ponds not assigned a Tier 1 or 2 (i.e. not protected by conservation land). A simple query was used to identify NULL classifications (after the Tier 1 and Tier 2 classification) and to identify stream orders of 4 or greater.
NOTE 2: In the original creation of the dataset the generation of double lines (that is, 2 lines for one stream segment representing each river bank of the segment) from the hydrography dataset did not generate the proper stream order for particular segments associated with double lined hydrography. However, spot checks were conducted on the major rivers to correct for this. Later iterations and methods for generating this dataset will be corrected to ensure that this will no longer be an issue.
Tier 4 and Tier 5 (Local Regulations): Tier 4 and Tier 5 is based on the presence of local zoning regulation for stream segments that do not fall into the Tier’s 1 – 3 criteria. The base data layer that identifies these communities with buffer protections in zoning ordinance was conducted in previous analysis and its results incorporated into this analysis. Stream segments were assigned to the Tier’s 4 or 5 if local zoning protected buffers according to the Tier 4 or 5 criteria and the stream/pond frontage was not assigned a higher Tier value (e.g. 1 – 3).
Tier 6 (No Protection): A Tier 6 classification indicates no protection for a stream segment. It is assigned to the all remaining river or pond frontage without protection identified and coded in the previous steps.