Fish Habitat and Culvert Surveys

Culvert Survey

A culvert survey was completed for all of WRIA 23 (Watershed Resource Inventory Area) located in Lewis County, and a portion of WRIA 23 located in Thurston and Grays Harbor Counties, Washington. The total area surveyed was 569,600 acres. Culverts, if improperly installed or deteriorated over time, can prevent or limit the ability of adult and juvenile salmonids to access all habitats. Coho salmon, searun cutthroat, and steelhead travel up into the smaller streams and are therefore more likely to be impacted by blocking culverts.

It is important that fish have access to all habitats to spawn, elude predators, find food, and escape high flows. However, a complete database that listed all the culverts in the system did not exist. Therefore, the Lewis County Conservation District undertook the task of finding and evaluating culverts. The data that was acquired was combined with existing information to make a complete map and database. This project was funded by grants from the Washington State Salmon Recovery Funding Board and the Chehalis Fisheries Restoration Program of the United States Fish and Wildlife Service. WRIA Survey of Salmon Habitat – Download Map File.

Upper Chehalis Culvert Statistics


When culverts are evaluated they fall into the categories of impassable, passable or unknown, based on the ability to pass a 6 inch trout. If a culvert is rated impassable it is not necessarily a total barrier to fish passage. It can be causing a delay or limiting a certain life-stage of the salmonid. A passable culvert allows the 6 inch fish to pass the culvert at all times. Unknown culverts were unable to have barrier status determined.

Culvert Barrier Status
YEAR
Impassable
2008
Passable
2008
Unknown
2008
Totals
2008
Corrected
2008
Newaukum Watershed
53
33
13
99
Skookumchuck Watershed
70
26
9
105
3
South Fork Chehalis
48
50
1
99
1
Upper Chehalis Watershed
43
28
1
72
Middle Chehalis Watershed
115
24
13
152
2
Centralia Chehalis
Area Tributaries
39
33
10
82
1
Lincoln and Scammon
Creek Watersheds
30
42
4
76

Independence and Garrard
Creek Watersheds
40
25
3
68

Scatter Creek and Prairie
Creek Watersheds
9
13
3
25

Southern Tributaries to the Lower
Chehalis River

Black River Watershed

37

45

12

94

Oakville and Porter Area Tributaries

23

20

3

46

McCleary and Elma Area Tributaries

70

31

1

102

Habitat Assessments

The Lewis County Conservation District utilizes the Washington State Department of Fish and Wildlife Salmonid Screening, Habitat Enhancement, and Restoration (SSHEAR). priority index method to rank the culverts that would benefit fish by being replaced. The Fish Passage Priority Index takes into account the habitat gain, the mobility and health status of the fish stocks that would benefit from increased access to the habitat, and the projected cost of the project. The fish passage priority index is a valuable tool to be used with other relevant factors to select projects for correction.