Agricultural Drainage for Landowners


Ag Drainage     Drainage Districts


Many agricultural lands in lowland Whatcom County are located within Special Districts charged with maintaining drainage of many watercourses.  To find out if your property is in one of these districts click here to view a map.  If your property is within a district click here to see that district’s Map, Drainage Management Plan and contact information.

If your property is not within a district then the landowner is usually responsible for maintaining drainage.  This page will provide step by step guidance to help you maintain your drainage and measures that can be taken to reduce the need for additional drainage maintenance in the future. 


Step 1 Watercourse Classification:DID Example


The first step is to determine whether your watercourse is classified as Natural, Modified Natural or Constructed. 

Natural watercourses are those that have never been significantly altered; these are rare in lowland Whatcom County. 

Modified watercourses are those that have some natural features, natural sources, or direct connections to functioning streams. 

Constructed watercourses are those that begin within agricultural fields and do not have any surface water sources.


Your Whatcom Conservation District GIS Specialist can help you determine your watercourses classification, contact.  However often times there is doubt as to whether a “ditch” should be classified as Modified Natural or Constructed.  In these cases the Washington Department of Fish and Wildlife’s Area Habitat Biologist should be consulted, Jeff Kamps 360-466-4345 ext 271,

Watercourse Classification Factsheet




Step 2 – Constructed Watercourses

(modified natural watercourses skip to Step 3)

Constructed watercourses can be maintained as needed with only a Natural Resource Notification to Whatcom County.  However measures should be taken to ensure that sediments do not contaminate modified natural waters downstream. 

Whether you choose to excavate the channel by hand or with excavation equipment, do it as cleanly as possible.  Leave exposed soils smooth and seed with grass to prevent erosion and repeated drainage problems.  Also consider planting a native tree or shrub Hedgerow to cast shade and prevent grass growth in the channel.  Finally implement good Farm Practices to keep field sediments from entering the watercourse and causing poor drainage.

Constructed Watercourse Maintenance Factsheet Farm Practices Factsheet
Hedgerow Poster



Step 3 Modified Natural Watercourses

(Constructed watercourses see Step 2)


A.   Permitting:  Any drainage maintenance work planned in or along modified natural watercourses will require permitting from Whatcom County and the Washington State Department of Fish and Wildlife (WDFW).  The links below will help you determine what permits are needed.  Once you become familiar with the process a good starting point is to contact WDFW Area Habitat Biologist Jeff Kamps 360-466-4345 ext 271, and arrange an on-site meeting to discuss your needs.

 Permitting Factsheet  Clean Water Regulations Factsheet
 Growth & Shorelines Management Acts Factsheet  Agency Contact Requirements Factsheets


B.    Best Management Practices:  The specific procedures below are intended to minimize the negative impacts drainage maintenance may have to the aquatic environment and other natural resources.  Appropriate BMPs must be included on permit applications and implemented on site to ensure clean and legal project implementation.

General Drainage Maintenance BMPs Factsheet  Maintenance Dredging BMPs Factsheets
 Beaver Dam Management Factsheet  Watercourse Vegetation Management Factsheet
 Aquatic Herbicides Factsheet Culvert Maintenance and Replacement Factsheet 
 Bridge Maintenance Factsheet  Sediment Traps Factsheet
 Fish Protection Factsheet  Water Quality Protection Measures Factsheet
 Hand Maintenance Factsheet 


C.    Mitigation, Habitat Improvement and Long Term Drainage Maintenance
As noted above drainage maintenance in modified natural watercourses will inevitably have negative impacts to the aquatic environment likely including poor water quality and damage to fish and fish habitat.  Regulatory agencies will likely require that mitigation of some kind be planned and implemented as a condition of permitting.  This mitigation must be designed to offset the negative impacts by improving the aquatic habitat or water quality in the long term. 

Although mitigation can take many forms, the most common practice is to restore native tree or shrub buffers along the watercourse following drainage maintenance.  Advantages of a re-vegetated streambank include:

  • Improved fish habitat from riparian cover.
  • Improved fish health from new riparian food sources (insects, plants).
  • Improved water quality from shade (lower temperatures, higher dissolved oxygen).
  • Reduced long term drainage maintenance needs from shade (shade will inhibit the growth of Reed canary grass allowing sediments to move with the water and not accumulate).
  • Reduced long term drainage maintenance needs from sediment control (riparian buffers will trap field sediments before they reach the watercourse and cause repeated drainage problems).
  • Funding is often available to assist landowners with planting and maintaining buffers.  Click here for more information.
Watercourse Re-vegetation Factsheet

 Hedgerow Poster


This page was last modified on 11/13/12 - 10:31