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Thurston County Stormwater Utility

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Maintaining Neighborhood Stormwater Facilities

Stormwater facilities are man-made structures and require maintenance to insure that they function properly over time. 

wet pond

Vegetation Management

Erosion and Sediment Control

  • add rock rip rap or other stabilizing measures as needed to prevent erosion
  • areas designed for sediment retention should have excess sediment removed periodically

Inlet/Outlet Pipe Inspection

  • if pipes are present in the facility, remove excess sediment and/or debris as necessary to insure water can enter and exit the pond as designed

Interested in a free workshop on maintaining your stormwater facility?  Email us at stormwater@co.thurston.wa.us to sign up for the next workshop.

Annual Stormwater Facility Inspections

As part of Thurston County's responsibility to prevent and minimize stormwater pollution, stormwater facilities must be inspected on an annual basis to ensure they continue to function properly.  Homeowners and private property owners responsible for the maintenance of a stormwater facility within Thurston County will receive an inspection form every year that must be completed by the property manager and/or owner, and returned to Water Resources staff at:

2000 Lakeridge Drive SW
Bldg 4, Room 100
Olympia, WA  98502

Inspection forms

Residential inspection formCommercial Pond Inspection formCommercial CB inspection form

Please download the appropriate form(s) to your hard drive and save a copy for your records after filling out the form.  Email the completed form to stormwater@co.thurston.wa.us 

Additionally, Thurston County Resource Stewardship staff inspects private and commercial stormwater facilities on an annual basis to ensure they are functioning properly. If any deficiencies are found, a report is sent to the responsible party with details on how to repair the problems(s). Within 30 days of receiving the report, property owners are required to return an enclosed inspection form stating that they either corrected the deficiencies, or plan to correct them at a specified point in the future.

Need to hire a contractor for your stormwater facility management needs?

Check Thurston County's list of stormwater-related contractors to find a company that may be able to help you complete necessary maintenance on privately-owned (neighborhood) stormwater facilities.

Thurston County's informative booklet on how to identify your stormwater facilities and keep them working: 

Maintaining Your Neighborhood Stormwater Facilities (PDF)

Common nuisance plants and control methods

Cattail (Typha latifolia)

Thurston County Water Resources staff recommends maintaining cattail populations in wet ponds at or below 25%cattail (Typha latifolia) coverage of the total wet pond area.  This is because cattail coverage over this amount can reduce the designed holding capacity of a pond and restrict flow in and out of the pond.

To control cattail in a wet pond, individual plants and their entire root system can be pulled out by hand.  This method is typically more successful where the plants are less deeply rooted in the looser soil in the middle of a pond than on the edges.  If removing cattail by hand is not practicable, cattail can be cut below the water line and all cuttings removed from the area.  The rhizomes (roots) of cattail plants that are continuously submerged at least three (3) inches below the water line will eventually die, although multiple cuttings in one year may be necessary to achieve success.

Scotch broom (Cytisus scoparius)

For small infestations, the entire plant and as much of the root system as possible should be removed from the area, as remaining roots can re-sprout.  The area should be monitored for several years to remove seedlings as they sprout.  For larger infestations, mechanical removal with the use of brush cutters, tractor-mounted mowers, or backhoes should be done when the plants are drought stressed (July through September) to achieve maximum mortality.

Thurston County Noxious Weed Fact Sheets (PDF)

Annual bugloss  Common bugloss 
Common reed (Phragmites) Dalmation toadflax
Giant hogweed Gorse
Mouseear hawkweed Orange hawkweed
Knotweeds Purple loosestrife
Pampas grass Perennial pepperweed
Perennial sowthistle Poison hemlock
Rush skeletonweed Shiny geranium
Spurge laurel Sulfur cinquefoil
Tansy ragwort Scotch thistle
Wild chervil Yellow flag iris

Field Guide to Noxious Weeds of Thurston County (PDF)

Contact Us

 Staff contact: Cathe Linn: (360) 867-2095. E-mail: stormwater@co.thurston.wa.us

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