Fisheries Resources and Habitat Assessment

Background

The Clackamas River Basin is one of two basins where wild coho spawn in the Lower Columbia Endangered Species Unit. Both Rock and Richardson Creeks have populations of anadromous and resident salmonids, as well as a number of other fish species. While these populations are small and localized they are regionally unique within an urban growth boundary and in an urbanizing area. Moreover, coho is a candidate species for listing under the ESA, and it is critical to protect all existing habitats. Stream surveys (ODFW 1999, Dewberry 1999) have noted the presence of a number of fish species in both watersheds, although Richardson Creek has not been as actively surveyed as Rock Creek.

Distribution of fish

Both natural and human barriers limit the distribution of salmonids. In Rock Creek a 20-foot waterfall lies about six tenths of a mile upstream of the creek mouth. Anadromous fish make use of the area below the falls for spawning and rearing. In-stream barriers in lower Rock Creek may inhibit movement during low flow periods. Two small tributaries below the falls also provide some limited habitat, although culverts just upstream block these. In middle Rock Creek, resident cutthroat trout have been found in a stretch of the mainstem between Foster Road and SE 172nd Avenues. These fish may be hemmed in by culvert blockages both upstream and down.

Fish Presence by Watershed
Anadromous Fish	Anadromous Fish
Winter Steelhead (Oncorhynchus mykiss)	Winter Steelhead (Oncorhynchus mykiss)
Coho (Oncorhynchus kisutch)	Coho (Oncorhynchus kisutch)
Chinook (Oncorhynchus tshawytscha)	Chinook (Oncorhynchus tshawytscha)
Resident Fish	Resident Fish
Cutthroat Trout (Oncorhynchus clarki clarki)	(detailed fish survey has not been done on Richardson Creek)
Speckled Dace (Rhinichthys osculus)
Largescale Sucker (Catostomus macrocheilus)
Red Side Shiner (Richardsonius balteatus)
Reticulate Sculpin (Cottus perplexus)
Longnose Dace (Rhinicthys cataractae)
Pacific Lamprey (Lampetra tridentata)
W. Brook Lamprey (Lampetra richardson)
Northern Pikeminnow (Esox Lucieus)
Torrent Sculpin (Cottus rhotheus)
Pumpkinseed (Lepomis gibbosus)*
Bullgill (Lepomis macrochirus)*
Largemouth Bass (Micropterus salmoides)*
Brown Bullhead (Ictalurus nebulosus)*
*introduced species

Lower Richardson Creek anadromous and resident salmonid populations range from the mouth of the Creek up one and a half to two miles. A debris dam caused by a slope failure is located about six tenths of a mile above highway 224 and may be temporarily or partially blocking upstream fish migration.

The Salmonid Distribution map shows the location of these barriers along with location and distribution of salmon and cutthroat trout. The distribution of salmonids shown on this map indicates actual known salmonid presence based on in-stream survey work.

Habitat quality

Studies by ODFW (1999) and Dewberry and Adams (1999) both indicate that habitat quality is marginal to moderately impaired in lower Rock Creek. The index of biological indicators (IBI) survey by Dewberry and Adams (1999) found low macroinvertibrate biodiversity in 1997, although numbers were much higher in 1998. ODFW (1999) noted a series of existing conditions that can cause problems for salmonids, including the following.

Low dissolved oxygen
High summer water temperatures
Limited spawning gravels
High sediment loading
Low summer flows
High seasonal flows
Limited refuge habita
Low frequency of pools
Low levels of large woody debris
Low levels of hiding cover

A lower Rock Creek snorkel survey conducted in July 2000 by Ecotrust found marginal visibility in pools and high algae production (indicating high temperatures and possibly low dissolved oxygen during early mornings). There were high populations of Shiners and Dace (which are more tolerant of high water temperatures), but no juvenile anadromous salmonids were found. The middle section of Rock Creek that contains resident cutthroat trout appears to be quite marginal habitat, though water quality tests were not conducted in this area. Nevertheless visual surveys indicate poor riparian cover, partly channelized stream sections, a lack of habitat complexity and a lack of refuge habitat.

Lower Richardson Creek appears to have better habitat than does Rock Creek. The snorkel survey conducted in July 2000 by Ecotrust focused on a section from Highway 224, upstream about one mile. The survey noted adequate visibility and a healthy riparian zone with good pool and riffle presence. Coho salmon, trout, cutthroat trout, and steelhead were identified, but there was a lower number and density of anadromous salmonids than might be expected. The slump and logjam in this section currently forms a partial barrier to upstream migration.

Department of Fish and Wildlife fish surveys and habitat analysis for Richardson Creek noted the presence of anadromous salmonids in Reach 1, which extends from the mouth of Richardson Creek upstream to where the stream branches into three tributaries, southwest of SE Barlow Court. URS Corporation, in their work on the Master Stormwater Plan for Clackamas County concluded that salmonids in Richardson Creek are primarily confined to Reach 1 due to a combination of factors including low summer flows, heavy sediment loading, substantial channelization of creek sections, numerous culverts (including an impassable one at Barlow Road), and a lack of in-stream habitat structure (Wolfe et al, 1999).

Rearing habitat for salmonids appears to be limited to Reach 1. While suitable, these conditions are below optimal due to low summer and fall flows, low frequency of pools, low pool depth, lack of adequate spawning substrate, and low in-stream cover.

Salmonid hot spots

Rock and Richardson Creek salmonid assessment Ecotrust's survey and analysis suggests that there are three critical areas or "hot spots" for salmonids in Rock and Richardson Creeks. These include (1) Lower Rock Creek, from the mouth up to the falls, (2) Middle Rock Creek, from SE 172nd east to Foster Road, and (3) Lower Richardson Creek. These areas all have confirmed salmonid populations and offer good potential for habitat restoration and species recovery. Two of the three have decent riparian zones and relatively good habitat. These three areas should receive special attention in terms of monitoring, protection, and restoration. If salmon cannot be retained in these sections, then they cannot continue to exist in these watersheds.

Additional information

The URS Corporation natural resources technical memorandum provides additional observations on fish populations and habitat quality for some of the individual reaches and tributaries in both Rock and Richardson Creek (Wolfe, K. et al, 1999, pgs. 12–21). Metro's draft Rock and Richardson Creek Landscape and Natural Resource Assessment includes a map (Map 8) of relative landscape values for fish habitat based on relative values (Apostol, et al, draft). While not based on empirical data this map indicates general areas that may have potential to support quality fish habitat.

Information gaps

Historic levels of salmonid populations in Rock and Richardson Creeks.

Recommendations for Basin Council

Develop a more detailed field assessment of culverts to identify migration barriers.
Continue the IBI surveys in lower Rock and Richardson Creeks. Begin IBI surveys in the Middle Rock creek hot spot.
Continue annual summer snorkel monitoring in Rock and Richardson Creeks.
Begin efforts to reach landowners and public officials with an aim of implementing measures to protect the three critical hot spot areas.
Interview long time residents to research past fish occurrence (see Olson et al, 2000).