Elwha Watershed Information Resource

Teacher and students preparing for water quality testing on the Elwha River with Olympic Park Institute. Olympic Park Institute

The water quality of both the surface and groundwater in the Elwha River watershed is considered of good quality, with more than 80 percent of the watershed protected within the Olympic National Park boundaries. When the two dams are removed, the water quality will be affected in the short term (for example, increased turbidity levels) and the long term as the water temperatures are reduced. The dams created high water temperatures in the summer months that caused increases in parasites, disease, and fish mortality in the lower river. By removing the dams, high summer and fall water temperatures will be reduced (National Park Service 1996). Additionally, some existing infrastructure (such as individual wells) will need to be modified after the dam removal to compensate for fluctuating water levels.

The water quality of the Elwha River is important not only to fish and wildlife, but also to people. Plants and animals in the Elwha watershed can be directly influenced by the factors (such as algae, temperature, and sediment) that affect water quality. People who live in Port Angeles use water that comes from a well located near the Elwha River, which is affected by surface water and groundwater in the watershed. Multiple jurisdictions (including federal, tribal, state, and county) will closely monitor the water quality of the Elwha River during dam removal to prevent harmful levels of conditions such as suspended sediments and turbidity.

Surface Water

Pre Dam Removal Status: The surface water in the area is rated as moderate-to-good quality on the water quality index. The index was developed by the Washington Department of Ecology as a way to rate the water quality using a scale from 1 to 100. Individual water quality parameters (such as fecal coliform bacteria, pH, and temperature) are measured and the overall water quality rating is calculated by combining the results for each of those parameters.

The index values are related to specific water quality levels:

• 0-39 = poor quality
• 40-79 = moderate quality
• 80-100 = good quality

Between 1994 and 2006, the overall water quality index of the Elwha River was between 73 and 88, which is considered moderate to good (although this rating was not adjusted for water quantity). The Elwha water quality is similar to other Olympic Peninsula river systems that have moderate-to-good water quality ratings, such as the Hoh River (with a score of 51-80 from 1994-2006) and the Dungeness River (with a score of 86-97 in 1994 and from 1999-2001).

However, for the years 2002 and 2004, the Environmental Protection Agency (EPA) 303(d) designated the Elwha River as a water body of concern-- along with 25 other water bodies within the Dungeness-Elwha watershed. It was designated as such due to temperature and polychlorinated biphenyls (PCBs) measurements that were above accepted levels in both years.

Water quality assessments of the Elwha River have taken place on a frequent basis by the Washington Department of Ecology since 1994. Water quality parameters monitored include fecal coliform bacteria, oxygen, pH, suspended solids, temperature, total persulfate nitrogen, total phosphorous, and turbidity. These parameters are important to human health and the health of the Elwha ecosystem. The presence of fecal coliform bacteria in the water indicates contamination from fecal matter (human and/or animal), which can create gastrointestinal illness in humans. Lack of oxygen, very low or very high pH, warm temperatures, and high turbidity can all stress and kill fish and aquatic life. Persulfate nitrogen and phosphorus control the production of algae in the water; too much of either can lead to excessive plant growth, low oxygen levels, and undesirable pH levels.

Post Dam Removal Considerations: Dam removal will impact the surface water quality by increasing suspended sediments and turbidity for short periods and possibly by increasing levels of dissolved manganese and iron that have built up in the reservoir sediments (NPS 1996). It is estimated that turbidity, suspended sediments, and dissolved manganese and iron will be at levels slightly or moderately higher than current conditions for two to six years after dam removal. Minor changes in pH, temperature, and dissolved gas will also result from dam removal. However, surface water users (for example, municipal and industrial water supply) will not be affected for the most part because their water goes through a pre-treatment process.

Groundwater

Pre Dam Removal Status: The groundwater in the area is considered to be good-to-excellent quality. The City of Port Angeles water quality report for 2005 included tests for over 315 contaminants. Copper was the only contaminant above its EPA action level, and this raised level was due to corroding pipes in residential houses (Consumer Confidence Water Quality Report 2006).

Over the years, periodic water tests have been conducted by the City of Port Angeles, the Dry Creek Water Association, and the Elwha Place Homeowners' Association. These tests measured levels of turbidity, coliform bacteria, inorganic chemicals, trihalomethane, volatile organic chemicals, and pesticides. Between 1983 and 1993, only iron and turbidity were detected above the maximum levels in the Port Angeles Ranney well samples (Elwha-Dungeness Planning Unit 2005). The source of iron was found in the sediments of Lake Mills. (Increased levels of iron and turbidity may cause disruption of groundwater delivery systems and mineral staining of fixtures and clothing.)

Post Dam Removal Considerations: Groundwater may be affected by an increase in fine sediments and by flooding, which could contaminate wells (NPS 1996).

• City of Port Angeles. Installation of a new Ranney collector on the opposite side of the river would provide quality municipal water supplies to the city.
• Individual well users. Due to fluctuating water levels, individual well users will need to raise their well heads, install in-line filters, create temporary storage tanks, and deepen existing wells (or create new wells).
• Residents on the Lower Elwha Klallam Reservation. Residents will experience higher groundwater levels that will make current septic systems unusable. A new wastewater system (such as a mound system) will need to be implemented prior to dam removal.
• New water treatment facility. A new water treatment facility will be constructed in concordance with dam removal and the problem, caused by corrosion of residential copper pipes, will be resolved by adjusting the pH in the treated water.

Reference

Consumer Confidence Water Quality Report. 2006. City of Port Angeles 2005 calendar year.

Elwha-Dungeness Planning Unit. 2005. Elwha-Dungeness Watershed Plan, Water Resource Inventory Area 18 (WRIA 18) and Sequim Bay in West WRIA 17. Published by Clallam County. Volume 1: Chapters 1-3 and 15 appendices; Volume 2: Appendix 3-E.

NPS (National Park Service). 1996. Elwha River Ecosystem Restoration, Draft Environmental Impact Statement. National Park Service, Olympic National Park, 600 East Park Avenue, Port Angeles, Washington, 98362.