City of Tillamook

Tillamook’s Storm Water Management Challenge

In 2004, the City of Tillamook undertook a study of the storm water sewer system that carries away storm runoff. The study was done because of increasing requirements under the Federal Clean Water Act, which is overseen through the Authority of the  Oregon Department of Environmental Quality (DEQ). Under these regulations, cities must prevent polluted storm water from being discharged into local rivers and streams. DEQ ultimately ordered the city to take steps to put a plan into action.

Tillamook is at the confluence of several rivers and streams. The city, which has grown up over more than 100 years, has a collection of storm sewers that were installed at various times – many without the planning needed to ensure proper operation. The 2004 study was designed to develop a master plan to correct the city’s storm water system deficiencies. Its primary purpose was to describe existing water quality problems in Tillamook Bay, identify the source points for these problems in Tillamook City’s storm water discharges and propose solutions.

As part of the study, engineers mapped the existing system and recorded the size and condition of underground storm water pipes, as well as junctions where multiple pipelines converge. Then the study team looked at seasonal storm water loads, factored in variations over years and periodic flood data. They used all of this information to map out a plan for improving the system and correcting problem areas.