ODFW AQUATIC INVENTORIES PROJECT

STREAM REPORT STREAM: Mitchell Creek LLID: 1224912454686 BASIN: Willamette River HUC NUMBER: 17090012 SURVEY DATE: August 22 - 27, 2019 ECOREGION: Willamette Valley Plains - Foothills STREAM ORDER: 1 USGS MAPS: Damascus and Gladstone WATERSHED AREA: 2.6km2

FIRST ORDER TRIBUTARIES: 0 SURVEY CREW: Ricky Hays and Aaron Taft REPORT PREPARED BY: Peggy Kavanagh GENERAL DESCRIPTION:

The Mitchell Creek stream habitat survey began at its confluence with Kelley Creek and ended at a property boundary. Five reaches were designated based on restoration activity, vegetation changes, and tributary influence. There were 2,390 meters of primary channel length and 65 meters of side channel habitat. The land uses were rural residential and urban. The stream habitat was comprised primarily of scour pools with fine organic material and gravel substrates. Twenty percent of the survey length was not surveyed due to access limitations caused by vegetation and lack of landowner support (denials or lack of response). Non-natives noted during the survey included reed canary grass, Himalayan blackberry, English ivy, Japanese knotweed, and English holly. The trees encountered most frequently during riparian transects were hardwoods 3-15cm dbh. REACH 1: (T01S-R03E-S19NW) – 201 meters – Reach 1 began at the confluence of Kelley Creek and

extended to restoration project area. There were 201 meters of primary channel habitat. The stream channel was constrained by terraces in a broad valley. The valley width index was 20.0. The average gradient was 2.9 percent. The land uses were rural residential and urban. The streamside vegetation included conifer trees 50-90cm dbh. Seventy-three percent of the reach was unsurveyed. The surveyed stream channel was composed of rapids (12%) and cascades (11%) with a mix of fine sediment (24%), gravel (34%), and cobble (28%) substrate. The average residual pool depth was 0.19 meters. Instream wood volume was 0.1m3/100m. Reed canary grass, English ivy, and Himalayan blackberry were noted during the riparian transect. The trees encountered most frequently during riparian survey were hardwoods 3-15cm dbh. Total number of trees per 100m2: 1.7 conifers and 4.0 hardwoods (based on 1 riparian transect).

REACH 2: (T01S-R03E-S19SW) – 308 meters – The second reach spanned the restoration project area.

There were 308 meters of primary channel length and 28 meters of side channel habitat. The stream channels were constrained by high terraces in a broad valley. The valley width index was 20.0. The land uses were rural residential and urban. The streamside vegetation included hardwood trees 3-15cm dbh. The average gradient was 0.9 percent. Scour pools (73%) with fine organic sediment (78%) dominated the surveyed stream habitat. The average residual pool depth was 0.08 meters. Instream wood volume was 3.1m3/100m. Himalayan blackberry was noted during the riparian transect. Deciduous trees 3-15cm dbh were encountered most frequently during the

riparian transect. The total number of trees per 100m2: 0.0 conifers and 1.0 hardwoods (based on 1 riparian transect).

REACH 3: (T01S-R03E-S19SW) – 1058 meters – Reach 3 extended from the restoration area to

geomorphic change. There were 1,058 meters of primary channel habitat. The stream channel was mostly constrained by high terraces within a broad valley with a valley width index of 20.0. The land uses were rural residential and urban. The average gradient was 1.6 percent. The streamside vegetation included hardwood trees 50-90cm dbh. The surveyed stream habitat was comprised predominantly of scour pools (24%) with fine sediment (76%) substrate. The average residual pool depth was 0.33 meters. Fifty-two percent of the reach was unsurveyed. Instream wood volume was 0.2m3/100m. Himalayan blackberry and reed canary grass were noted in the riparian transect. Conifers 30-50cm dbh and hardwoods 3-15cm dbh were the trees encountered most frequently during the riparian transect. The total number of trees per 100m2: 1.7 conifers and 2.0 hardwoods (based on 1 riparian transect).

REACH 4: (T01S-R03E-S30NW) – 749 meters – Reach 4 ended at a tributary junction contributing

approximately 60 percent of the stream flow. There were 749 meters of primary channel length and 37 meters of side channel habitat. The stream channels were constrained by alternating hillslopes and high terraces in a broad valley. The average valley width index was 7.2 (range: 5.5-9.0). The land uses were rural residential and urban. The streamside vegetation included a mix of conifer and hardwood trees 50-90cm dbh. The average gradient was 1.2 percent. Scour pools (66%) with fine sediment (73%) and gravel (26%) dominated the stream habitat. The average residual pool depth was 0.29 meters. Fourteen percent of the stream units had undercut banks. Instream wood volume was 30.1m3/100m. Himalayan blackberry was noted during the riparian transects. Hardwood trees 3-15cm dbh were encountered most frequently during the riparian transects. The total number of trees per 100m2: 1.3 conifers and 4.8 hardwoods (based on 4 riparian transects).

REACH 5: (T01S-R02E-S25NE) – 74 meters – Reach 5 extended from an unnamed tributary to a property

boundary. There were 74 meters of primary channel habitat. The stream channel was constrained by hillslopes and high terraces within a broad valley. The average valley width index was 4.5 (range: 1.0-8.0). The land uses were rural residential and urban. The streamside vegetation included conifer trees 50-90cm dbh. The average gradient was 3.5 percent. The stream habitat was comprised predominantly of scour pools (72%) with fine organic sediment (67%), gravel (18%), and bedrock (10%). The average residual pool depth was 0.25 meters. Instream wood volume was 8.0m3/100m. Himalayan blackberry was noted in the riparian transect. Conifer trees 30-50cm dbh were encountered most frequently during the riparian transect. The total number of trees per 100m2: 3.0 conifers and 1.3 hardwoods (based on 1 riparian transect).

COMMENTS: Fish were infrequent during the survey and the last fish was observed at unit 110 (2245m). A fish

presence / absence survey was not conducted.

Potential barriers to fish movement included a step of concrete pieces (unit 21, 1005m) 0.7m high and a step at a spillway (unit 57, 1701m) 0.8m high.

Wildlife observations included Pacific tree frog, red-legged frogs, signal crayfish, bull frog, and an

unknown frog. The restoration area in Reach 2 included recently-cut blackberry canes, erosion control mesh, and

placed boulders and logs. Refer to the photographs and Comment Summary for examples of channelized stream channel,

bridge crossings, potential barriers, restoration features, and examples of vegetation. The upstream UTM coordinates for each stream habitat unit were recorded and listed in the

Comment Summary. Due to capture error, unique coordinates were not collected for all units.

Non-native plants noted during the habitat survey included reed canary grass, Himalayan blackberry, English ivy, Japanese knotweed, and English holly.

Select non-native plants in the Comment Summary were listed in order of presence within each habitat unit, and in some cases, the side of the stream where encountered. Ex. Veg=/EI, HBB/ indicates that English ivy was on the right bank and Himalayan blackberry was

on the left bank. The “/” indicates the side of the stream, where ‘xx/’ = left bank and ‘/xx’ = right bank.

Ex. Veg=EI/EI, HBB/, English ivy was on both sides of the stream and in greater presence than the blackberry which was on the left bank.

Ex. Veg=EI, HBB indicates that there was more English Ivy than Himalayan blackberry and both were present on both sides of the stream. The lack of ‘/’ signifies that the vegetation was not bank-side-specific.

Reach 1 - Unit 1 - Looking downstream from the beginning of the survey. Reach 2 - Unit 5 - Recently-cut blackberries along and in stream channel.

Reach 2 - Unit 7 - Looking upstream and downstream at the streamside restoration.

Mitchell Creek (Johnson Creek Basin) 2019 Summer Habitat Survey Photographs

Reach 2 - Unit 8 - Restoration project on pond / wetland with placed large wood and removed invasive plants.

Reach 3 - Unit 21 - A large piece of concrete. A remnant from channelized stream bank material?

Reach 3 - Unit 26 - A submerged culvert crossing 1m diameter.

Reach 4 - Unit 69 - A view of the stream channel and streamside vegetation.

Mitchell Creek (Johnson Creek Basin) 2019 Summer Habitat Survey Photographs

Reach 4 - Unit 39- Looking downstream at a culvert crossing, which marks a property boundary and the new reach.

Reach 4 - Unit 66 - Concrete wall diverting stream flow. Perhaps former dam or depth measuring station.

Reach 5 - Unit 117 - An upstream view of the stream channel near the survey end.

Reach 4 - Unit 58 - A culvert crossing (1.3m diameter) under SE 162nd Ave. The drop from culvert to stream channel was 0.8m high.

 

Overview of Mitchell Creek