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Water Infrastructure in the Mid-Coast Region

Built Systems Snapshot


Potable (drinking) water, wastewater, and stormwater systems are critical for the health of humans and the economy. Built Systems in the Mid-Coast region was summarized during Step 2 of the planning process. The entire report on water quality can be accessed here.

  • The Mid-Coast has 52 potable water providers, 31 of which are required to have certified water treatment plant (WTP) operators. These 52 water providers include cities, water districts, RV and mobile home parks, and state parks.

  • Few interconnections exist between water providers.

  • Many cities and water districts implement water conservation measures, and nine have developed Water Management and Conservation Plans (WMCPs).

  • The Mid-Coast has 14 entities (cities, resorts/hotels, and industries) with National Pollutant Discharge Elimination System (NPDES) permits to discharge treated wastewater.

  • Discharge locations are the Pacific Ocean, Yaquina River and Bay, Siletz River and Bay, Schooner Creek, and Lint Slough. The discharge locations on streams are all downstream of potable water intakes.

  • Information about wastewater systems and, particularly stormwater systems, is lacking. 

  • Cities are likely the only water providers managing stormwater systems.

  • The Mid-Coast, like much of the rest of the United States, has aging infrastructure and insufficient revenue to address many needed upgrades. Consequently, water systems in the Mid-Coast must be managed for resiliency and recovery.


Potable (Drinking Water Systems)


Potable water systems consist of the points of diversion/points of appropriation, raw water and finished water distribution systems, and water treatment plants (WTPs). WTPs remove contaminants from raw water to produce water that is considered safe for human consumption. Most community water systems with surface water sources use the treatment steps shown in the graphic to the right.

Potable water systems are classified as small water, water distribution, or water treatment based

on size and complexity:

  • A Small Water System has fewer than 150 connections and either uses only groundwater as its source, or it purchases water that needs no further treatment after reaching the purchasing system.

  • Distribution systems, with four levels of complexity, are classified on the basis of population served.

  • WTP has four levels of complexity based on a point system assigned to reflect the complexity of the treatment process used at the plant.

31 Mid-Coast drinking water providers are required to have certified WTP

operators whereas 21 drinking water providers are not required to have certified WTP operators.


Graphic credit: Water Quality & Health Council.

Wastewater Systems


Wastewater systems are sewer systems, wastewater treatment plants (WWTPs), effluent discharge infrastructure, and effluent recycling systems (e.g., biosolid land application). Effluent is the treated liquid that comes out of the treatment plant after completion of the treatment process. 

Wastewater treatment accelerates the natural process by which water is purified. WWTPs treat wastewater in two stages, primary and secondary. In the primary stage, wastewater first flows through screen that removes large floating objects that might clog equipment. Next, the wastewater passes through a grit chamber where sand and small stones settle to the bottom. Then the wastewater moves into a sedimentation tank in which suspended solids gradually sink to the bottom and form a mass of solids called raw primary biosolids, or sludge. These biosolids are typically removed from tanks by pumping, and they may be further treated for use as fertilizers, disposed of in a landfill, or incinerated.


In the secondary stage, biological processes are used to further purify wastewater. About 85% of organic matter in sewage is removed in the stage using bacteria. The secondary stage often uses the activated sludge process, which involves pumping water from the sedimentation/settling tank in the primary stage into an aeration tank where the wastewater is mixed with air and sludge loaded with bacteria, and then left alone for several hours to allow bacteria to break down organic matter into harmless byproducts. This mixture, or sludge, is now activated with billions of bacteria and some of it can be used again by returning it to the aeration tank for mixing with air and new wastewater. After the aeration tank, the partially treated wastewater flows to another sedimentation tank for removal of excess bacteria, and scum. Finally, effluent from the sedimentation tank is typically disinfected with chlorine, ultraviolet light, or ozone before the effluent is discharged into waters.


Graphic: 2012 Encyclopedia Brittanica, Inc.

Wastewater discharged from WWTPs into the environment is regulated by DEQ through the NPDES permit program. Occasionally, the wastewater system is unable to treat the water that enters the wastewater system, such that some wastewater is forced out of the system without treatment, which results in sanitary sewer overflows into creeks, the ocean, and neighborhoods.



Wastewater systems produce biosolids, or treated sewage sludge. Biosolids are the solids derived from primary, secondary, or advanced treatment of domestic wastewater that have been treated through one or more controlled processes to significantly reduce pathogens and reduce volatile solids, or chemically stabilize solids to the extent that they do not attract disease vectors. These solids are treated to meet state and federal requirements that allow for their beneficial use in land application activities. Most Class B biosolids generated from domestic wastewater treatment facilities in Oregon are land applied on agricultural land and have some regulatory limitations. Class A biosolids are classified as exceptional quality (EQ) biosolids and may be land applied without regulatory

limitations. Click here for more information on biosolids in Oregon.

Stormwater Systems


Stormwater systems collect precipitation (e.g., rainfall and snowmelt) to avoid pooling and flooding. In the Mid-Coast, precipitation typically enters drains and then is conveyed through pipelines to outfalls, such as a stream or the ocean. Stormwater is not treated in the Mid-Coast, and local stormwater system information is limited. The Oregon Department of Transportation and EPA have stormwater resources to access online.

Examples of municipal stormwater management efforts include the City of Portland, Oregon and the City of Florence, Oregon​.

Water Conservation


Water conservation can reduce demand of water sources, particularly peak day demands that typically drive the need for major infrastructure upgrades. Water conservation includes measures related to infrastructure management and customer water uses. Many water providers develop conservation plan, which is designed to help water providers examine their water rights, current and future demands, water source reliability and adequacy, and water conservation program. Water conservation plans are required to contain descriptions of progress implementing the following water conservation measures: annual water audit, system metering and meter

maintenance, rate structures based in part on the quantity of water metered at service connections, leak detection and repair, and public education.

Currently, the Mid-Coast has nine water providers with WMCPs: the Cities of Depoe Bay, Lincoln City, Newport, Toledo, Waldport, and Yachats; Seal Rock Water District; Kernville-Gleneden Beach-Lincoln Beach Water District; and Southwest Lincoln County Water Public

Utilities District.Other water providers voluntarily implement water conservation measures.


Click here for more information on municipal water management and conservation planning in Oregon.

Click here to access the toolkit for water conservation.

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