Water Quality Improvement Project
Newman Lake Area:
Total Phosphorus


Newman Lake is located in Spokane County, Washington, 26 kilometers northeast of the city of Spokane. It is approximately nine meters deep and contains about 26 million cubic meters of water. The lake is fed primarily by Thompson Creek.

The main land use around Newman Lake is forestry, but also pastureland and residential housing. Residential use is generally highest during the summer months. (See TMDL boundary map)

Water quality issues

Water quality studies of Newman Lake show that the high availability of the nutrient phosphorus has lead to increased algae growth during the summer months. The algae growth has, in turn, lead to reduced water clarity and decreased available oxygen in the deeper portions of the lake during the summer. These changes result in impacts to the majority of aquatic resources that were adapted to a lower phosphorus condition.

Other studies determined that there are two sources for phosphorus to Newman Lake: that within the bottom sediments (internal), and phosphorus brought to the lake, for example from surface water runoff (external).

  Newman Lake with double rainbow in lake and sky, Washington State.  Photographer Candy Redl.  Courtesy of newmanlake.com.

© Candy Redl, newmanlake.com .

Why this matters

Excessive nutrient inputs to lakes provide aquatic plant and algae dominance, making lakes unsuitable for recreation or viewing enjoyment. Phosphorus is one of the nutrients. When it is discharged into a waterbody, like a lake, it fuels the growth of algae.

Excessive algae growth reduces water clarity, increases oxygen demand in the bottom sediments severely impacting coldwater aquatic habitat, and can, depending on the dominant algae present, pose a human health risk.

Status of the project

Ecology submitted the water quality improvement report (WQIR, also known as a total maximum daily load, or TMDL) to EPA in December 2007. EPA approved it in February 2008.

A TMDL advisory committee was formed to provide input on necessary actions to meet the TMDL requirements. The resulting draft Newman Lake TMDL Water Quality Implementation Plan (WQIP) underwent a public review and comment period. The finalized WQIP was sent to EPA in July 2009.

Technical information

Newman Lake Total Phosphorus Total Maximum Daily Load: Water Quality Improvement Report (Ecology Publication)

Newman Lake Total Phosphorus Total Maximum Daily Load: Water Quality Implementation Plan (Ecology publication)

Related information

Watershed Information for WRIA 57 (Environmental Assessment Program web site)

Repairing Wave-Damaged Shoreline: Homeowner effort to save New Lake property has water quality and wildlife benefits (Ecology publication)

WRIA 57: Middle Spokane Watershed Information (Environmental Assessment Program web site)


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Last updated May 2015
Water resource inventory area (WRIA) 57 map, Washington State.


WRIA: #57 (Middle Spokane)
County: Spokane

Water-body Name:
Newman Lake

Total Phosphorus

# of TMDLs: 1

Approved by EPA
Has implementation plan

Contact Info:
David Knight
Phone: 509-329-3590
Email: David.Knight@ecy.wa.gov

Eastern Region
Department of Ecology
N. 4601 Monroe
Spokane, WA 99205-1295

Tony Whiley
Phone: 360-407-7241
Email: Tony.Whiley@ecy.wa.gov

Watershed Management Section
Department of Ecology
P.O. Box 47600
Olympia, WA 98504 -7600