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Watershed of the Month- Mainstem Nooksack River

The Mainstem Nooksack River lies downstream of the three forks: the North Fork, Middle Fork, and South Fork. From the confluence of the Middle and North Fork, the mainstem flows 36 miles through low lying agricultural and rural areas, as well as, the communities of Deming, North Cedarville, Nooksack, Everson, Lynden, Ferndale, and the Lummi Nation before discharging into Bellingham Bay. Many major tributaries of the mainstem form sub-basin watersheds throughout Northern Whatcom County and portions of Canada. For inventory purposes, the Mainstem Nooksack River may also be viewed as a sub-basin that includes an area where ground and surface water directly drain into the mainstem or its minor tributaries. The tributaries included in this sub-basin are Anderson Creek, Smith Creek, McCauley Creek, Cougar Creek, Scott Ditch, Schneider Ditch and Wiser Lake.

This sub-basin is 52,694 acres (82 square miles) in size and encompasses a population of 12,988 people. Land uses within the sub-basin include residential (7,246 acres), and commercial (703 acres). Undeveloped or open space (18,917 acres) accounts for a large portion of land, mostly concentrated in the upper portion of the watershed, at the higher elevations. However, the majority of land use within the sub-basin is agricultural (19,752 acres). There are intensive agricultural practices along the river, such as dairy operations and raspberry farms. The numerous raspberry growers are among leading producers statewide and nationally. If not properly managed, agricultural land uses can impact both water and fish habitat quality along the Mainstem Nooksack River. Other human impacts within the sub-basin that affect the quality of the stream include wastewater treatment plants that discharge into the mainstem and extensive systems of hardened or leveed riverbank to control flooding. In addition, the conversion of agricultural and undeveloped land for residential and commercial land use is accelerating and could negatively impact the environmental quality of the Mainstem Nooksack River watershed.

The impacts of agriculture on water quality in the Mainstem Nooksack sub-basin are typical of other agricultural watersheds. For example, there are elevated levels of nitrogen and phosphorus. However, according to water quality standards for surface water in the State of Washington, currently water quality in most of the Mainstem Nooksack River and minor tributaries is consistent with Class A (Excellent). This grade is based on levels of dissolved oxygen and pH, which are critical for fish survival. Although most of the mainstem qualifies as excellent for pH and dissolved oxygen levels, there are other water quality issues. There is a particular concern for levels of fecal coliform bacteria in the river and tributaries in the valley between North Cedarville and Brennan, downstream of Ferndale. In this area, two segments of the mainstem were listed on the State Department of Ecology’s 303(d) list of impaired surface water for elevated levels of fecal coliform bacteria. Fecal coliform comes from human and animal waste. The elevated levels in the river may be a result of leaking septic systems or agricultural practices, such as livestock grazing near or in the river or tributaries.

Maintaining or restoring high water quality is the Mainstem Nooksack sub-basin is very important since it provides habitat for several fish species, including ten native salmonids. Chum, pink, coho, chinook, sockeye, steelhead, coastal cutthroat, mountain whitefish, bull trout and dolly varden are all native species found in the mainstem. Poor agricultural practices, urban and industrial land uses, and other human impacts have greatly affected the quality of habitat. In additional to water quality problems, the installation of flood control structures has altered the river’s form and hydrology. Also water diversions have reduced instream flows and urban and industrial development has altered land cover along the banks and floodplain. The losses of wetlands, lack of shade, and low summer flows have all contributed to warmer water temperatures. The sub-basin historically provided excellent rearing habitat for many salmon species. Chum and late chinook use the river for spawning, but the mainstem also acts as a corridor to prime spawning habitats upstream in the forks and tributaries.

There are several agencies making efforts towards improving water quality in the Mainstem Nooksack sub-basin. In May 2000, the State Department of Ecology (DOE) developed a strategic plan to clean up water pollution in the entire Nooksack River drainage basin. They requested, by 2001, all diaries to have pollution control strategies within farm plans approved by the Whatcom Conservation District. The intent is to reduce levels of fecal coliform bacteria and nutrients entering watercourses. The DOE has also put stricter limits for fecal coliform bacteria on water discharged by sewage treatment facilities within the watershed. The Whatcom County Planning and Development Department has hired additional inspectors to enforce local manure and stream buffer ordinances. This enforcement is expected to further reduce animal access to streams and manure application to bare ground or during the wet season. Stream buffers should help filter pollutants and provide shade that will help cool water temperatures. The Nooksack Salmon Enhancement Association has worked extensively with small landowners along lowland streams to voluntarily re-establish riparian zones. The Whatcom Conservation District also provides funding to implement such riparian buffers on agricultural land through the Conservation Reserve Enhancement Program (CREP).

The Mainstem Nooksack River is being influenced by the changing land use within the watershed. Some areas are restoring floodplains and cleaning up pollution and other areas are pressured to meet population growth with further development. With the majority of land use of the sub-basin currently as agriculture, the restoration of riparian areas on these lands is vital to recover salmon habitat functions.

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