Lacamas Field Report — July 15, 2026

June 19 marked our third monthly sample of seven sites in the upper watershed of Lacamas Lake testing for phosphates and orthophosphates. The first two samples, taken in mid-April and mid-May 2026, indicated elevated phosphate levels in two streams: Fifth Plain Creek and Lacamas Creek.

China Ditch, upstream from the testing site at Fifth Plain Creek, has had phosphate levels significantly different from other streams to the east, with orthophosphates 4-20 times higher and phosphates 10 times higher, showing highly eutrophic (overly enriched with nutrients) conditions.

This appears to explain higher phosphate levels noted in downstream samplings at (1) Fifth Plain Creek just below where China Ditch and Shanghai Creek merge and (2) Lacamas Creek just above the entrance to Lacamas Lake. Eutrophic conditions were show by our samples but at lower levels, diluted from other streams entering the watershed.

We await the third set of data and expect to confirm that one or more sources of phosphates are coming from China Ditch. As this is a first effort in sampling for Lacamas Watershed Council, we are cautious about drawing any firm conclusions. Lacamas Watershed Council will decide the next steps thereafter.