Department of
Environmental Quality

Subbasin at a Glance

Overview

The Potlatch River watershed, part of the Lower Clearwater River Subbasin, drains into the Clearwater River between Myrtle and Spalding. The upper reaches of the Potlatch River are divided into two main tributaries, the East Fork and West Fork Potlatch Rivers. The East Fork originates in the northwest corner of Clearwater County and flows southwest to its confluence with the mainstem. The West Fork originates in the northwest corner of Latah County and flows southeast to its confluence with the Potlatch River. The Potlatch River drains the eastern two-thirds of Latah County, running from northeast to southwest.

Monitoring was conducted biweekly in 2002-04. Water quality parameters and pollutant concentrations measured included stream temperature, E. coli bacteria and fecal coliform bacteria, dissolved oxygen, ammonia, total nitrogen and total phosphorus, turbidity and total suspended solids, pH, and stream flow. Based on data collected, DEQ is establishing TMDLs to control temperature, bacteria, excess nutrients, and sediment in various water body segments in the Potlatch River watershed.

TMDLs to restore stream temperatures to background conditions by increasing riparian shade were developed for all listed water bodies in the Potlatch River watershed (see table below). Temperature is a key factor in the quality of water bodies and the health of fish and other aquatic species.

Bacteria TMDLs were developed to control E. coli bacteria in several creeks (see below). E. coli bacteria wasteload allocations also have been developed for five wastewater treatment facilities (Bovill, Deary, Juliaetta, Kendrick, and Troy) that discharge to the Potlatch River or associated tributaries and estuaries.

Nutrient TMDLs were developed to control excessive aquatic plant growth in Pine and West Fork Little Bear Creeks.

Lastly, sediment TMDLs were developed for several creeks (see below).Waste load allocations were developed for the Deary, Bovill, Kendrick, Juliaetta, and Troy wastewater treatment facilities based on the estimated design flow, the maximum daily limit, and the current allowable average monthly concentrations. Controlling sediment loads will assist in managing nutrient loads in the Potlatch River watershed since nutrients, particularly phosphorus, bind to soil particles delivered to the stream.

In addition, DEQ recommends removing various other pollutants from the list of pollutants associated with these water bodies because they are no longer impairing water quality.

A growth reserve is not included in the TMDLs. Except for stormwater construction permits, future sources will need to acquire a load allocation from existing allocations unless the load capacity is increased.

Streams and Pollutants for Which TMDLs Were Developed

Potlatch River (Big Bear Creek to Mouth)

Temperature, sediment

Potlatch River (Corral Creek to Big Bear Creek)

Temperature

Potlatch River (Moose Creek to Corral Creek)

Temperature

Potlatch River (Headwaters to Moose Creek)

Temperature, bacteria

Big Bear Creek

Temperature, bacteria

Boulder Creek

Temperature, bacteria

Cedar Creek

Temperature, sediment

Corral Creek

Temperature

Moose Creek

Temperature, bacteria

Pine Creek

Temperature, nutrients, sediment

Ruby Creek

Temperature, bacteria

E. Fork Potlach River

Temperature

Middle Potlatch Creek

Temperature, bacteria, sediment

W. Fork Little Bear Creek

Bacteria, nutrients, sediment

Subbasin Documents

• Potlatch River Subbasin Assessment and TMDLs (September 2008)