Appendix D—Description of the


Riparian Protection Zone Strategy (Proposed Action)


Four biophysical principles underlie the development of any 

riparian/aquatic protection strategy. These are: 1) a stream 

requires predictable and near-natural energy and nutrient 

inputs; 2) many plant and animal communities rely on 

streamside forests and vegetation; 3) small streams are 

generally more affected by hill-slope activities than are larger 

streams; and 4) as adjacent slopes become steeper, the 

likelihood of disturbance resulting in discernable in-stream 

effects increases. (Quigley and Arbelbide, 1997). 

Proposed fuels treatments will incorporate Riparian 

Protection Zones (RPZs) designed to protect specific key 

ecological functions of these areas. These are not necessarily 

no-treatment zones. Rather, they are areas where riparian 

resources and key functions receive primary management 

emphasis and design features must be applied to protect the 

key ecological functions. The key functions to be protected 

are: 

(1)	 water quality, to a degree that provides for stable and 

productive riparian and aquatic ecosystems; 

(2)	 stream channel integrity, channel processes, and the 

sediment regime (including the elements of timing, 

volume, and character of sediment input and transport) 

under which the riparian and aquatic ecosystems 

developed; 

(3)	 instream flows to support health riparian and aquatic 

habitats, the stability and effective function of stream 

channels, and the ability to route flood discharges; 

(4) natural timing and variability of the water table 

elevation in meadows and wetlands; 

(5) diversity and productivity of native and desired nonnative plant communities in riparian zones. 

Because stream types and riparian function are extremely 

variable across the planning area, an RPZ based on a 

minimum linear distance will not be applicable to every 

project. Thus, the width necessary to protect stream and 

riparian area structure and function should be determined 

from watershed and site-specific analysis. 

Each project developed under this Environmental 

Assessment will incorporate specific design features to 

maintain the key ecological functions of the RPZs. 

Project plans and Environmental Assessment should 

specifically document the analysis process used to determine 

final dimensions of RPZs. Recommended RPZ boundaries 

for projects carried out under this EA are described below. 

Based on a substantial body of theoretical and applied 

science, projects implemented using RPZ boundaries as 

designated below will be much less likely to adversely affect 

aquatic species and their habitats. These should be 

considered default boundaries until final boundaries are 

determined by watershed or site-specific analysis. Final 

boundaries may be narrower or wider, depending on local 

conditions and results of the project specific analysis. 

Interim Riparian Protection Zones-Forested Areas 

Interim boundaries of the RPZs within forested zones of 

the planning area will be: 

(1)	 Streams, ponds, lakes containing Special Status Fish 

Species: two site-potential tree heights. 

(2) Other fishbearing streams: one site-potential tree height. 

(3)	 Ponds, lakes, and wetlands greater than 1 acre: the 

interim RPZ consists of the body of water or wetland 

and the area to the outer edges of the riparian vegetation, 

or to the extent of the seasonally saturated soil, or to 

the extent of moderately and highly unstable areas, or 

to a distance equal to one site-potential tree height 

(whichever is greatest) 

The interim boundaries for RPZs within forested zones of 

the planning area are based on site-potential tree height. The 

maximum height of dominant trees is one of the most 

significant factors influencing the extent of the streamside 

area directly affecting channel and aquatic ecosystem 

function. For instance, tall trees potentially contribute shade, 

particulate organic matter, and large woody debris at greater 

distances from streams than do short trees. Areas capable of 

producing large tall trees thus possess wider functional 

riparian zones than areas in which trees do not grow as large. 

For this reason, FEMAT (1993), PACFISH (1995), and 

INFISH (1995) used the height of dominant latesuccessional tree species that would naturally grow in a 

particular riparian zone as the basis for reconnecting 

streamside buffers needed to safeguard ecological functions 

instead of a fixed “one-size-fits-all” linear distance. Use of 

a fixed distance from the streambank to the outer margin of 

the buffer strip would not allow for differences in potential 

tree growth between regions. 

Interim Riparian Protection Zones-Non-Forested 

Areas 

In non-forested rangeland ecosystems, the interim RPZ 

would consist of the body of water or wetland and the area 

to the outer edges of the riparian vegetation, or to the extent 

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of the seasonally saturated soil, or to the extent of moderately 

and highly unstable areas, or (in segments where trees are 

present) to a distance equal to one site-potential tree height 

(whichever is greatest). 

Design Features for Isolated Populations 

The EA identified particular risk from wildfire and fuels 

management projects to isolated, depressed populations in 

degraded habitats without access to local or regional refugia 

(e.g. westslope cutthroat trout). All projects carried out under 

this EA will incorporate the following to ensure that potential 

effects to these species are reduced to non-significant levels: 

(1)	 areas proposed for fuels reduction projects will be 

surveyed for the presence of these populations 

(2)	 During project-specific NEPA analysis, project planners 

will include a specific assessment for these species. The 

assessment will specifically identify potential sources 

or risk and the specific design features incorporated in 

the project to avoid adverse effects or to mitigate them 

to the insignificant level. 

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