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Water Quality and Permits
The Comprehensive Stormwater Management Plan is intended to assist the Spokane County Stormwater Utility in developing a cohesive strategy to prioritize, finance, and implement the capital projects and operating programs recommended in the various planning documents into a combined master plan. (View Here)
Eastern Washington Stormwater Effectiveness Studies
Sand Filter Sidewalk Vault BMP:
The focus of this study was to evaluate the stormwater treatment performance of a new potential best management practice (BMP) referred to as the sand filter sidewalk vault. This BMP fits in a 4-foot by 5-foot vault installed below the sidewalk that receives runoff through a curb cut located in the street gutter. The sand filter media consists of 18-inches of coarse sand overlaid by a coconut coir mat.
- SAND FILTER SIDEWALK VAULT FACT SHEET (Summary)
- TECHNICAL EVALUATION REPORT (TER) SAND FILTER SIDEWALK VAULT BMP (Full Report)
Bioretention Soil Media Thickness Study:
The focus of this study was to evaluate the effectiveness of bioretention cells containing an 18-inch bioretention soil media (BSM) layer in comparison to a 12-inch BSM layer. Bioretention cells are shallow landscaped depressions which are designed to capture and treat stormwater runoff from small contributing areas.
- BIORETENTION SOIL MEDIA THICKNESS FACT SHEET (Summary)
- TECHNICAL EVALUATION REPORT (TER) BIORETENTION SOIL MEDIA THICKNESS STUDY (Full Report)
The Eastern Washington LID Guidance Manual is a collaborative product of Spokane County, the Washington State Department of Ecology, the Washington Stormwater Center, Washington State University, and Eastern Washington Phase II Municipal Stormwater Permittees. Funding for the project to create the manual was provided by the Department of Ecology.
Eastern Washington LID Guidance Manual
NPDES Phase II Stormwater Permit
Under a directive from the EPA, the Washington State Department of Ecology issued Spokane County a National Pollutant Discharge Elimination System (NPDES), Eastern Washington Phase II Municipal Stormwater Permit (NPDES Permit) in February 2007. The guiding law behind the NPDES Permit is the Federal "Clean Water Act," which regulates the discharge of pollutants to waters of the United States.
Here's the link to view the current Eastern Washington Phase II Municipal Stormwater Permit (NPDES Stormwater Permit). It is also available on the Ecology Website.
Frequently asked questions about Municipal Stormwater Permits can be viewed here.
For questions or to learn more about the NPDES Permit and minimum control measures visit the Washington State Department of Ecology webpage.
NPDES - Pollution Prevention Ordinance
On July 21, 2009 the Spokane County Board of of County Commissioners approved amendments to Spokane County Code, Chapter 9.14, Roads, Approach and Drainage in New Construction, to meet the state mandated pollution prevention requirements of the Eastern Washington Phase II Municipal Stormwater Permit (NPDES Permit). This ordinance is designed to prevent water pollution and protect water quality within our rivers, lakes, streams, and aquifer. View Spokane County Code, Title 9, Chapter 9.14 (PDF).
Stormwater Management Program Plan
The purpose of this Stormwater Management Program Plan (view) is to describe the programs and practices used by the County to manage the Municipal Separate Storm Sewer System (MS4) and to aid in the implementation of required Permit programs. This Plan:
- is updated annually to describe upcoming permit year activities;
- describes on-going programs in place to comply with Permit conditions;
- outlines staffing and funding responsibilities for permit programs; and
- applies to the 5-year duration of the current Permit cycle (expiring July 31, 2024).
Upkeep of this Plan furthers the County’s long-term commitment to minimizing pollutants discharged to Waters of Washington State
 A Municipal Separate Storm Sewer system is the municipally owned stormwater conveyance system including curbs, roads, catch basins, etc. and it is not connected to the sanitary sewer system.
Underground Injection Control are also known as “dry wells”.
The Underground Injection Control program was created by Congress to protect underground sources of drinking water from discharges of fluids to the ground. The UIC program in the state of Washington is administered by the Department of Ecology. In Washington State all ground water is protected equally under RCW 90.48 and Chapter 173-200 WAC Water Quality Standards for Ground Waters of the State of Washington.
The two basic requirements of the UIC Program are:
- Register UIC wells with the Washington State Department of Ecology unless the wells are located on tribal land. Well on tribal land should be registered with the Environmental Protection Agency.
- Make sure that current and future underground sources of ground water are not endangered by pollutants in the discharge non-endangerment standard.
Since stormwater picks up contaminants as it runs over the land surface, it can pollute ground water once infiltration occurs. Pollution of ground water from stormwater discharges can be prevented by careful design of the UIC well, strategic siting and effective operation and maintenance. Pollution can also be prevented by use of treatment before discharge to the sub-surface and by reducing the stormwater contact with potential sources of contamination.
UIC wells must be registered. For more information visit Ecology's website.
Spokane County adopted engineering design standards and stormwater BMPs as described within the Spokane Regional Stormwater Manual (SRSM). The SRSM was approved by the Board of County Commissioners on April 15, 2008, and became law on June 1, 2008, replacing the existing Spokane County - Guidelines for Stormwater Management. The SRSM is considered by the Department of Ecology to be an equivalent to the Stormwater Management Manual for Eastern Washington (SWMMEW).
The following chapters of the Spokane County Code address stormwater design, management, and maintenance requirements: 1) Chapter 9.14 – Roads Approach and Drainage in New Construction; 2) Chapter 12.400 – Subdivisions; and 3) Chapter 14.802.060 – Parking Lot Location and Design.
Spokane County Code, Title 8, Health and Sanitation Code, Chapter 8.03 – Sanitary Sewer, includes various sections that address illicit discharges within Spokane County. The primary relevant sections include: 8.03.1570 POTW; 8.03.1710 – Private Storm Sewer; 8.03.1730 – Prohibited Discharge Standards or Prohibited Discharges; 8.03.1750 – Public Sewer; 8.03.1830 – Sewer; 8.03.1990 – Stormwater; 8.03.2010 – Storm Sewer or Storm Drain; 8.03.3200 – Prohibited Uses of Sanitary Sewer; 8.03.3220 – Use of Storm Sewers--Combined Sewers--Natural Outlets; 8.03.3260 – Obstructing Sewer Prohibited; 8.03.3300 – Unauthorized Connection to Public Sewers; 8.03.3240 – Prohibited Uses--Public Sewers; 8.03.4040 – Prohibited Discharge Standards--General Prohibitions; 8.03.4060 – Prohibited Discharge Standards--Specific Prohibitions.
Spokane County Code, Title 8, Health and Sanitation Code, Chapter 8.26 – Litter and Discriminate Dumping, includes various sections that are relevant to protecting the integrity of stormwater and other surface waters, such as Section 8.26.020 – Litter in General, which addresses the disposal of litter upon any public place or private property, or within any waters in Spokane County. This Chapter also addresses notice of violation, enforcement, and penalty.
Spokane County Code, Chapter 8.60.030 – Oil Sellers--Educational Responsibilities, requires sellers of lubricating oil to do the following: 1) post educational materials that describe the importance of used oil recycling and how and where used oil may be recycled, and 2) provide for the sale of reusable used oil containers.
Spokane County implements flood controls through Title 3, Buildings and Structures, Chapter 3.20 – Flood Damage Protection. This is a comprehensive flood control ordinance that manages development within delineated floodplains in compliance with the National Flood Insurance Program.
2008 amendments to Spokane County Code, Chapter 9.14 – Roads, Approach and Drainage in New Construction, were developed and approved (Resolution No. 09-0672) to address illicit discharge regulations, including:
Prohibition of illicit discharges to the MS4
Spill Control, dumping, and disposal of materials other than stormwater to the MS4
Compliance with conditions in ordinances related to stormwater discharges
Inspection and monitoring procedures necessary to determine compliance and enforce the prohibition of illicit discharges to the MS4
In 2013, the Eastern Washington Low Impact Development (LID) Guidance Manual was developed as a supplemental guidance for the design, construction, and maintenance of LID stormwater Best Management Practices (BMPs). This manual was a regional effort led by the County in conjunction with many Eastern Washington municipalities, including the Washington Stormwater Center, Ecology, and regional LID experts.