Surface Water QuestionsNewcastle’s Surface Water Management Program addresses both water quality (pollutants) and water quantity (flood control) problems.

Management of stormwater prevents physical damage to property from flooding and maintains the ecological integrity, quality and quantity of our local water resources.

Here's a look at what the city does:

Stormwater System Maintenance

Stormwater maintenance staff inspect our publicly owned or maintained storm drainage systems on a regular basis to verify the structural integrity of our infrastructure.

During inspections, City staff also verify that there are not any illicit discharges or connections to the stormwater system, as well as check the sediment accumulation levels in structures.

Based on their inspections, City staff make needed repairs, remove sediment and pollutants from our stormwater system, and perform routine maintenance such as mowing detention ponds. Our stormwater staff protect water quality by removing pollutants from storm drains, ditches, ponds, and underground facilities.

Storm Water inspection Private Stormwater Inspection Program

The City works with local business and property owners to ensure that privately owned stormwater systems are functioning properly by inspecting and requiring maintenance or repairs be completed if necessary. These inspections and regular maintenance helps the stormwater systems to function as they were designed and prevents water quality degradation, downgradient erosion, and flooding. The City will notify business or property owners by letter prior when is it time for their next inspection.

For Property and Business Owners

Maintenance requirements for typical stormwater facilities can be found in Appendix A of the 2016 King County Surface Water Design Manual.

Capital Improvement Projects

The City repairs, retrofits, and adds new stormwater facilities where needed for water quality and water quantity control. The City also restores and enhances our streams and wetlands. Our new Comprehensive Surface Water Management Plan will be completed in May 2017, and will prioritize future storm or surface water Capital Improvement Projects.

Development Review

The City provides stormwater development review for development and redevelopment in Newcastle. As per the City’s NPDES permit, we are required to adopt updated surface water design standards that guide stormwater design within Newcastle.

Surface Water Design Manual and Low Impact Development

In December 2016, the City adopted the 2016 King County Surface Water Design Manual, along with our City Surface Water Design Manual Addendum.

The City adopted code amendments that encourage low impact development (LID) principles to minimize the loss of native vegetation and reduce runoff from developed sites. The 2016 KCSWDM requires on site flow control best management practices (BMPs) to mitigate the impacts of storm and surface water runoff generated by new impervious surfaces, new pervious surfaces, existing impervious surfaces, and replaced impervious surfaces. Flow control BMPs are methods to disperse, infiltrate, or otherwise reduce or prevent development related increases in runoff at or near the sources of those increases. The 2016 KCSWDM provides specific design guidance for implementation of the LID measures encouraged in the City’s development code. As a result, the 2016 KCSWDM and the City development code complement each other.

Public Works Standards

The city is currently in the process of updating the stormwater public works standards. Check back later for updates.

Design Resources

All development projects in Newcastle require erosion control and an Erosion and Sediment Control (ESC) plan, and must be submitted to the City for review. Some projects need a Construction Stormwater General Permit (CSGP), issued through the Washington State Department of Ecology.


Who needs a CSGP?

1.) Does your construction project disturb one or more acres of land through clearing, grading, excavating, or stockpiling of fill material?

Remember to count the cumulative acreage of the entire project whether in a single or in a multiphase project. This applies even if you are responsible for only a small portion [less than one acre] of the larger project planned over time.

2.) Is there any possibility that stormwater could run off your site during construction and into surface waters or conveyance systems leading to surface waters of the state?

In almost every case, the answer to this question is yes. However, if the topography and location of your site is such that there is no possibility that rainfall or snowmelt could leave the site or enter a waterway, you do not need permit coverage.

If you answered "yes" to both of these questions, your construction site needs a permit. Construction site operators must apply for a permit 60 days prior to discharging stormwater. As part of a CSGP, the Permittee must develop a Construction Stormwater Pollution Prevention Plan (SWPPP).

Important Links:
Focus on Construction Stormwater General Permit
Department of Ecology Construction Stormwater General Permit
Construction Stormwater General Permit Application Form (Notice of Intent, or NOI)
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