| Blazed Alder Creek | |
| Name Etymology: | A 24inches blazed (marked) alder tree near the mouth of the creek. It was used as a benchmark during early watershed surveys.[1] |
| Map Size: | 300 |
| Pushpin Map: | USA Oregon |
| Pushpin Map Size: | 300 |
| Pushpin Map Caption: | Location of the mouth of Blazed Alder Creek in Oregon |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | Oregon |
| Subdivision Type4: | County |
| Subdivision Name4: | Clackamas and Multnomah counties |
| Length: | 4miles[2] |
| Discharge1 Location: | 600feet downstream of the source[3] |
| Discharge1 Min: | 1cuft/s |
| Discharge1 Avg: | 57.5cuft/s[4] |
| Discharge1 Max: | 2610cuft/s |
| Source1: | Mount Hood National Forest |
| Source1 Location: | Blazed Alder Butte, Clackamas County, Oregon |
| Source1 Coordinates: | 45.4514°N -121.8892°W[5] |
| Mouth: | Bull Run River |
| Mouth Location: | Multnomah County, Oregon |
| Mouth Coordinates: | 45.4964°N -121.9217°W |
| Mouth Elevation: | 1699feet |
Blazed Alder Creek is a tributary, about 4miles long, of the Bull Run River in the U.S. state of Oregon.[2] Part of the system that provides drinking water to the city of Portland, it flows generally north through a protected part of the Mount Hood National Forest in Clackamas and Multnomah counties. The creek is named after a 24inches blazed (marked) alder tree that was used as a benchmark during early watershed surveys.[1]
Formed by the confluence of Bedrock Creek and Hickman Creek in Clackamas County, Blazed Alder Creek begins slightly north of Blazed Alder Butte and flows through the Mount Hood National Forest to meet the Bull Run River in Multnomah County. The creek lies entirely within the Bull Run Watershed Management Unit, a restricted area meant to protect the water supply for the city of Portland. Flowing north from its source in the western foothills of the Cascade Range, the creek passes a United States Geological Survey (USGS) stream gauge before receiving Nanny Creek from the left just before leaving Clackamas County and entering Multnomah County. Further downstream, it receives an unnamed tributary from the left before entering the Bull Run River.[6]
Since 1963, the USGS has monitored the flow of Blazed Alder Creek at a stream gauge 3.68miles from the mouth and only 600feet from the source. The average flow between then and 2009 was 57.5cuft/s. This is from a drainage area of 8.17sqmi. The maximum flow recorded during this period was 2610cuft/s on December 22, 1964. It occurred during the floods of December 1964 and January 1965, rated by the National Weather Service as one of Oregon's top 10 weather events of the 20th century.[7] The minimum was 1cuft/s on December 2 - 7, 2003.[3]
The Bull Run River watershed, which includes Blazed Alder Creek, drains 139mi2.[8] Most of the watershed, including all of the Blazed Alder Creek basin, is restricted to uses related to water collection, storage, treatment, and forest management. The Portland Water Bureau and the United States Forest Service manage the watershed.[9]