|Abstract or Summary
- The overall goal of this study was to determine if the Tillamook Bay tributaries'
water quality has improved as a result of the Best Management Practices (BMP) installed
at Tillamook County Dairies.
The Rural Clean Water Program (RCWP) was a 10 to 15 year experiment designed to
control agricultural non-point source (NPS) in rural watersheds throughout the nation. The
RCWP Tillamook Watershed Project in Tillamook County, Oregon promoted the installation
of manure management facilities and nutrient management strategies to improve the water
quality of Tillamook Bay. The goal of the project was to reduce the fecal coliform
concentration by 70%.
Since the Bay is used for oyster production, there has been extensive sampling of
Tillamook Bay and its tributaries since 1960. Unfortunately, much of the tributary data were
compiled for a variety of short-term projects and therefore, the area lacks a consistent strategy
for data collection. This inconsistency coupled with the variability in the data has made it
difficult to evaluate changes in the water quality.
It is important to note that this analysis is not a prediction model. It is a statistical
model using an analysis of variance (ANOVA). The term, model, will be used to describe the
response of ANOVA. This model is the best representation of the trend given the limited
useful data that was available.
The 33 year "tributary" analysis of the Wilson River station (D412130) determined
fecal coliform concentration reductions as high as 69.83, 62.67, 69.02 and 72.38% in the
Spring, Summer, Autumn and Winter, respectively. There were 48.59, 36.41, 47.21 and
52.95% reductions during the RCWP years (1980-1992) that may be attributed to the
BMP's. The BMP installation began in 1981 and continued through 1995, however, the
majority of the BMP's installation began in 1983.
These reductions are not at optimum levels because of three important factors.
First of all, not all farms have been provided with fullest possible array of manure
containment facilities. Secondly, even with full implementation, some fecal coliform
bacteria may escape. Finally, the BMP's must be diligently operated and maintained to
provide the most effective capture and die-off of fecal coliform bacteria. When the BMP's
are correctly installed and well managed, they will provide the maximum manure
containment protection for the streams.