The following summary is based on data from the 2023 Watershed Health Index. The scores below are a snapshot of conditions across the entire watershed. Conditions can vary in smaller parts of the watershed.
The scores from 2019 and 2015, the first year Environmental Services released the report cards, are included.
Water Quality Score: C
The creek has a poor E. coli bacteria score. In Portland, E. coli levels are lower in Johnson Creek since the City completed the Mid-County Sewer Project. Current E. coli hot spots are likely related to septic systems outside the city limits. Some studies indicate that animal waste is also a source of E. coli in the creek.
Within Portland, continuing stormwater management will reduce suspended solids and other pollutants. Allowing more stormwater to soak into the ground helps replenish groundwater and inputs cooler water to reduce water temperatures in the creek. Projects like the Johnson Creek Oxbow Restoration Project that restore native vegetation and wetlands will improve water quality.
Scores for Water Quality Indicators
Scores are on a scale of 0 to 10 with scores of 8 or higher meaning the indicator is properly functioning. A score of 3 or lower means the indicator is not functioning properly or provides little to no support for a healthy watershed. Find more information about the indicators and how to read the scores.
| Water Quality Indicator | 2023 Score | 2019 Score | 2015 Score |
|---|---|---|---|
| Ammonia-Nitrogen | 9.9 | 9.9 | 9.8 |
| Dissolved Copper | 6.7 | 6.8 | 6.9 |
| Dissolved Oxygen | 7.6 | 7.8 | 8.3 |
| E. coli | 2.6 | 2.6 | 4.0 |
| Temperature | 1.0 | 1.7 | 1.8 |
| Total Mercury | 1.7 | 1.8 | 1.4 |
| Total Phosphorus | 6.4 | 6.1 | 6.3 |
| Total Suspended Solids | 2.5 | 2.1 | 1.9 |
Habitat Score: C+
The Johnson Creek watershed has a low score for bank conditions, mainly because of rock armoring installed along 15 miles of creek banks in the 1930s. During the last few decades, the City has aimed to restore floodplain area and remove the rock armoring as part of those projects to reduce flooding and improve water quality. Culverts located on tributary streams affect stream accessibility scores. Between 2015 and 2019 many habitat scores improved due to Crystal Springs Creek and Luther Road restoration projects.
A relatively high tree canopy score is due to protected forested upland areas in the East Buttes. In residential and industrial areas with below-average canopy, tree planting is important. New plantings will further improve scores in the future as the vegetation matures.
Scores for Habitat Indicators
Scores are on a scale of 0 to 10 with scores of 8 or higher meaning the indicator is properly functioning. A score of 3 or lower means the indicator is not functioning properly or provides little to no support for a healthy watershed. Find more information about the indicators and how to read the scores.
| Habitat Indicator | 2023 Score | 2019 Score | 2015 Score |
|---|---|---|---|
| Bank Condition | 2.9 | 0.6 | 1.8 |
| Floodplain Condition | 5.0 | 6.0 | 6.0 |
| Large Wood | 2.4 | 2.5 | 2.6 |
| Riparian Integrity | 5.4 | 5.7 | 5.6 |
| Shallow Water Refugia | Not applicable | Not applicable | Not applicable |
| Stream Accessibility | 4.2 | 4.2 | 3.6 |
| Substrate Composition | 10 | 6.5 | 6.6 |
| Tree Canopy | 6.9 | 6.9 | 6.9 |
Hydrology Score: A
Environmental Services and partners have restored several miles of stream bank. Projects to restore Johnson Creek floodplain and stream banks continue. Between 2015 and 2019, hydrology scores improved, likely due to the Crystal Springs Creek projects.
Scores for Hydrology Indicators
Scores are on a scale of 0 to 10 with scores of 8 or higher meaning the indicator is properly functioning. A score of 3 or lower means the indicator is not functioning properly or provides little to no support for a healthy watershed. Find more information about the indicators and how to read the scores.
| Hydrology Indicator | 2023 Score | 2019 Score | 2015 Score |
|---|---|---|---|
| Effective Impervious Area | 9.1 | 8.5 | 7.5 |
| Stream Connectivity | 7.4 | 7.5 | 7.1 |
Fish and Wildlife Score: D+
Johnson Creek hosts a variety of fish species, including salmon and other native species. The creek is a prime resource to support recovery of endangered salmon in Portland. But total numbers of salmon and trout in Johnson Creek are low. High stream temperatures and a lack of large wood limit the ability of salmon and other native fish to grow and thrive. The result is low scores for fish and aquatic insects. Continued investment in riparian area improvement, floodplain restoration, and culvert removal will improve fish and wildlife quantity.
Scores for Fish and Wildlife Indicators
Scores are on a scale of 0 to 10 with scores of 8 or higher meaning the indicator is properly functioning. A score of 3 or lower means the indicator is not functioning properly or provides little to no support for a healthy watershed. Find more information about the indicators and how to read the scores.
| Fish and Wildlife Indicator | 2023 Score | 2019 Score | 2015 Score |
|---|---|---|---|
| Birds | 4.6 | 3.0 | 4.2 |
| Fish | 1.8 | 1.9 | 2.5 |
| Macroinvertebrates | 4.1 | 3.6 | 4.3 |
In Summary
This report card shows there is room for improvement, even after restoration work. Past projects have helped to restore some of the floodplain and remove some of the rock armoring from creek banks and culverts from streams. High stream temperatures and lack of large wood continue to limit the ability of fish to thrive. To improve scores, we are pursuing more projects that improve riparian areas, continue floodplain restoration, and remove culverts.
Read more about the Johnson Creek watershed.