Lewis and Clark National Historical Park - Environmental Factors

A Water Quality Baseline Inventory of the park was initiated in September of 1995. Sites sampled in this inventory included the Lewis and Clark River, 2 permanent streams, 1 ephemeral stream, 2 ephemeral springs, 3 ephemeral ponds and 1 slough. All sites were sampled 3 times per month throughout the year, in the case of the ephemeral sites until they dried up in the summer and beginning again in the fall when the water returned.
Water quality samples included readings and measurements for temperature, conductivity, salinity, turbidity, pH, alkalinity and dissolved oxygen. Stream flow measurements were taken in the streams and springs. Nutrient and ion analyses were performed by an outside contractor three times during the inventory.
In November of 1998 the Baseline Inventory was ended and the Long Term Monitoring Inventory was begun. The sites chosen for long term monitoring were based on results of the Baseline Survey. Sites included the Lewis and Clark River, 2 permanent streams, 2 ephemeral ponds and 1 ephemeral spring. A sampling schedule has been set up for each individual site and is based on seasonality and results of the Baseline Survey. This monitoring program is ongoing at the present time.


Weather
In June of 1998 the park service signed a Cooperative Agreement with the National Weather Service wherein Fort Clatsop would receive a basic Weather Station and would record daily weather observations (maximum and minimum temperatures and precipitation amounts) for the NWS. These observations are reported monthly to the weather service office in Portland, Oregon.
The park"s Resource Management Division has compiled weather records for previous years from the NWS internet site for the Astoria Regional Airport, which for many years housed a National Weather Service Station. The Airport is located only about two miles from Fort Clatsop.
The park"s climate is mild and wet with annual precipitation averaging around 70 inches. Seasonal and daily temperature fluctuations are minimal. Average monthly maximum temperatures range from 47 to 67 degrees F. Average minimums range from 35 to 53 degrees F.