OR-AMS Technical Meeting Summary: November 11, 2005

Eight members and guests came to the Columbia River Inter-Tribal Commission (CRITFC) near downtown Portland to hear Kyle Dittmer (CRITFC’s Hydrologist-Meteorologist) talk about how hydrologic, weather, oceanographic, and geologic factors come together to impact salmon populations (a cold water species). Given the endangered state of most west coast salmon populations, it is important to know what may help, or hurt, these magnificent creatures.

The hydro factors include the change in the timing and amount of water that flows down the Columbia River (as either rain, snow-melt, or both), flow fluctuations, and the slack water created by reservoirs. Although the Pacific Northwest hydro-system has been created to benefit people, the result has partially resulted in the decline of salmon stocks. A slower river means longer travel times to the ocean, more predators, and warmer water.

The weather factors include water temperature and rainfall patterns. Salmon are very sensitive to water temperatures and hydro-dam operations play a significant role, especially during summer. Salmon can actually sense rainfall on a river and field studies suggest they move and migrate in response to rainfall.

The oceanographic factors include coastal upwelling, El Nino and La Nina events, and the Pacific Decadal Oscillation. The short term impacts of what we now know as ENSO events plays a big role in ocean survival, with El Nino making for “sour” ocean conditions and La Nina making for “good” ocean conditions.

The geological factors include the quality of streambed gravel, consistent streamflow (for habitat), and groundwater seeps into the river channel. Salmon have consistently demonstrated a remarkable ability to recover from geologic disasters (e.g., Mt. St. Helens eruption of 1980) and quickly re-colonize an area.

Note-taker: Kyle Dittmer, OR-AMS President