| Spring River | |
| Map Size: | 300 |
| Pushpin Map: | USA Oregon |
| Pushpin Map Size: | 300 |
| Pushpin Map Caption: | Location of the mouth of the Spring River in Oregon |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | Oregon |
| Subdivision Type4: | County |
| Subdivision Name4: | Douglas |
| Length: | 1.1miles |
| Source1: | Cascade Range |
| Source1 Location: | a spring complex on Pumice Flat, Umpqua National Forest |
| Source1 Coordinates: | 43.2994°N -122.1353°W[1] |
| Source1 Elevation: | 4255feet[2] |
| Mouth: | North Umpqua River |
| Mouth Location: | upstream of Lemolo Lake |
| Mouth Coordinates: | 43.3078°N -122.1353°W |
| Mouth Elevation: | 4157feet |
| Basin Size: | 25.5sqmi[3] |
The Spring River is a short but significant tributary of the North Umpqua River in Douglas County in the U.S. state of Oregon. It begins at a spring complex in the Cascade Range on Pumice Flat in the Umpqua National Forest and flows 1.1miles north into the North Umpqua in Kelsay Valley, upstream of Lemolo Lake.[4] Evidence suggests that nearby Thirsty Creek has an underground connection to the Spring River and that underground connections from other sources exist.
The underground water feeding the springs emerges along the contact between glacial deposits and ash-flow deposits that form the bedrock. Although Spring River and other nearby spring-fed streams are short, their total water contribution to the North Umpqua is significant, especially during dry months.[5]
Thirsty Creek is a perennial stream that flows on the surface upstream of Spring River but sinks underground about 0.5miles before reaching it. Even so, it appears likely to researchers that it is part of the same watershed and contributes to the Spring River flow. Evidence also suggests that below-surface connections from elsewhere feed into Spring River. The low-flow discharge at the mouth of the river was measured at 210cuft/s on August 10, 1997, more than Thirsty Creek alone could account for and more than half of the North Umpqua flow above Lemolo Lake.[5]
Spring River is a spawning ground for kokanee from Lemolo Lake and brown trout from the lake and the river. The river has good spawning gravels, a stable flow, and desirable temperatures for fish. The water from the springs emerges at 5C and warms to between 10C11C between source and mouth.[5]