General Info | Water Quality

Safe and Clean Quality Water

Cascade is all about water - for today and tomorrow - and that means safe and clean water. Cascade's water is of the highest quality, and as new sources come on line, Cascade will treat water to meet or exceed all federal, state, and local quality standards just as our partners Seattle and Tacoma's Public Utilities do today. Extensive monitoring will be conducted prior to designing and constructing a state of the art treatment facility at Lake Tapps. Actual water quality and regulations applicable at the time Cascade builds the plant will determine the exact type and level of treatment required. Ongoing water quality testing and monitoring will be done. Across the country, many surface supply sources similar to Lake Tapps are used for recreation, with treatment technology making these sources extremely safe for drinking water as well.

To establish baseline water quality in Lake Tapps, Cascade has cooperated in a number of monitoring efforts since 2004, with The Washington Department of Ecology in 2004 - 2005 and with Pierce County Public Works and Utilities, the Muckleshoot Indian Tribe and the Puyallup Tribe of Indians in collecting water quality data during the 2004-2007 time frame.

The most recent and most comprehensive water quality monitoring was conducted in 2010 with the US Geological Survey (USGS), in cooperation with Cascade and the Muckleshoot Indian Tribe and the Puyallup Tribe of Indians. It established a baseline set of data collected under the flow regime contained in the Water Rights Permits for selected reaches of the White River, White River flowline, Lake Tapps and the Tailrace. A total of 13 sites-two on the White River, one on the White River flowline, one on the Tailrace returning flow back to the White River, and nine sites on Lake Tapps were sampled. Water samples were collected monthly or bi-monthly at the other river sites. The nine lake sites were sampled bi-monthly from July through October and monthly in November and December.

The water-quality data collected for this study consist of concentrations of nutrients, suspended solids, fecal-coliform bacteria, water temperature, specific conductance, dissolved oxygen concentration, pH, and turbidity continuously measured by in-situ water-quality sondes. Water-quality data collected from the Lake included vertical profiles of various water-quality and physical properties through the Lake water column. In addition, a one-time sampling of water from three of the Lake sites was analyzed for organic chemicals.

The following is a brief overview summary of the results of the 2010 effort:

  • Water from the White River, White River Flowline, and Tailrace sites generally was turbid, warm, chemically dilute, and well-oxygenated. The quality generally was good and generally met the freshwater criteria designated by Washington State Department of Ecology for recreational and aquatic-life uses.
  • Lake Tapps water near the surface was relatively clear, warm, and well oxygenated. Lake Tapps water is pH neutral and chemically dilute. Concentrations of nutrients and chlorophyll a in Lake Tapps were low. Lake Tapps generally fits within the oligotrophic classification and primary production is phosphorus limited.
  • In addition to general water quality parameters, water samples collected at three sites were screened for the presence of 250 organic chemicals. A total of 14 compounds (mostly belonging to the group of wastewater indicator chemicals) were detected in trace amounts (or determined to be present) at one or more of the three sites. Compounds detected (or with verified presence) at all three sites included the herbicide 2,4-D, the insecticide and mosquito repellant DEET, the herbicide fluridone used for Eurasian watermilfoil eradication, and the herbicide prometon.