Water Quality Decline Continues

April Markiewicz is a toxicologist and the associate director at the Institute of Environmental Toxicology at Huxley College of the Environment at Western Washington University, as well as president of the People for Lake Whatcom Coalition.

Similar to last year’s 2010/2011 Lake Whatcom Monitoring Annual Report results, the 2011/2012 monitoring results indicate that water quality is still declining in our community’s drinking water source (Matthews, et al., 2013). The good news is that the rate of decline continues to be much slower than in previous years, with some water quality parameters appearing to have leveled off and stabilized.

There are a number of possible explanations for this trend. Matthews, et al., (2013) has attributed the slowing decline to unusually cool weather in the spring and summer months that our region has periodically experienced over the last several years. As we intuitively know, cooler temperatures slow down biological processes, i.e., metabolism, growth, and reproduction. In aquatic systems, cool water temperatures not only slow down algal and bacterial productivity, but also cause changes in species distributions, abundance, seasonal dominance patterns, and interactions.

Cool water temperatures also affect physical and chemical properties of the lake. The onset of thermal stratification in the lake is delayed, which shortens the duration that the deeper lake water is isolated from mixing with the re-oxygenated surface water. Oxygen deficits in deeper waters are therefore usually less severe and that, in turn, decreases the amount of nutrients and other sediment-bound pollutants that dissolve out of the sediments and back into the overlying water. Those pollutants include metals like lead, mercury, iron and phosphorus.

As you look at the data in the following figures, you will note that starting in 2007 some of the data show a leveling-off (algae and blue-green bacteria, Figures 3 and 4) or actual decrease, as in the case of phosphorus (Figure 2). Some data, however, show that water quality degradation is continuing (Figures 1 and 5). For comparison, look at the data for 2003 through 2005, when water temperatures were unusually warm. The data show accelerated increases in algal numbers, total phosphorus, and chlorophyll (an indicator of algal biomass), with concurrent severe oxygen depletions once the lake stratified, especially in the smaller northern basins.

The slowing rate of decline could also be due to efforts by the city of Bellingham (city), Whatcom County, and the Lake Whatcom Water and Sewer District to control, limit, and prevent development from occurring in the watershed. They have also worked since 2002 to capture and treat stormwater runoff before it enters the lake from existing residential areas. In fact, at a recent meeting in March of this year, city staff reported that its efforts have achieved a 40 percent reduction in phosphorus inputs to the lake. At that rate of success, staff are optimistic that the city might be able to achieve an 80 percent reduction in 15 – 20 years (Schwartz, 2013). Continued investment in its watershed land acquisition program, installation of additional large stormwater treatment facilities, and its homeowner incentive program are crucial to achieving that goal.

For more information about requirements mandated by the Washington state Department of Ecology (Ecology) to reduce both phosphorus and bacteria (fecal coliform) from Lake Whatcom, readers are referred to an excellent overview by Wendy Harris, in the April, 2013 issue of the Whatcom Watch.

Another explanation is that it could just be the natural biogeochemical fluctuations in Lake Whatcom that are inherent to large, dynamic ecosystems. Lake processes are dominated by how the lake was created (glacial, tectonic, manmade), its size, shape, location, elevation, watershed geological properties, surrounding vegetation (or lack thereof), inflows and outflows via tributaries, and proximity to human activities and urban development. As such, variations from year to year are not only a function of the amounts and types of inputs (nutrients, chemicals, particles) entering the lake, but also the responses of the lake’s biological organisms to those inputs under changing environmental conditions.

Tributaries discharging into the lake from the surrounding watershed can contribute significantly to this variability. They have unique rates of flow, volumes of water, chemical and nutrient properties, particle loads, water temperatures, and biological communities that are also subject to changing environmental conditions. Inputs from the 36 tributaries in the Lake Whatcom watershed therefore have the potential to add to the variability in the lake’s water quality. Moreover, catastrophic events like floods and landslides can have profound effects on water quality throughout the entire lake. For example, in January, 1983 a massive landslide in the Smith Creek watershed sent an estimated 80 acres of mud, trees and vegetation, as well as a house, into the lake. The effects on water quality were detected years after the event. Other landslides in 2004, 2009, and 2011 have occurred in the watershed since then, indicating that these are not rare events and can have a significant effect on water quality over the long term.

What the Data Show

The following is a synopsis of the 2011/2012 Lake Whatcom Monitoring Program Annual Report (Matthews, et al., 2013)

Surface water temperatures in Basins 1 and 2 were slightly cooler than usual in June; the same was true for Basin 3 in July.

The rate of oxygen loss in the deeper water, once the lake stratified, was very rapid despite slightly cooler temperatures in June. Dissolved oxygen levels dropped to less than 1 mg/L by August, lower than levels measured in 2011 (see Figure 1).

Median near-surface summer total phosphorus levels continue to decline in all basins (see Figure 2). Last year, the declines only occurred in Basins 1 and 2. Long-term trends over a 10-year span indicate levels may be stabilizing.

Median near-surface summer chlorophyll concentrations continue to decline in all three basins (see Figure 3).

Counts of Chrysophyta (diatoms), green algae (Chlorophyta), and blue-green bacteria (Cyanobacteria) indicate populations may have stabilized during the last 7 years, and may be slightly decreasing in numbers (see Figure 4).

Algal blooms during the summer months again clogged the city’s water treatment filters for a fourth year in a row, causing poor water filtration rates at the water treatment facility. Only the early implementation of voluntary water restrictions prevented mandatory restrictions from being imposed later in the summer.

Fecal coliform bacteria levels in all three basins of the lake were less than 10 colonies/100 ml of sample, a magnitude lower than the standard of 100 colonies/100 ml. Samples collected at Bloedel-Donovan park were also well below the state standard.

THMs Increase

Trihalomethanes (THMs), which are known carcinogens, continue to increase in our tap water, especially in late summer and fall (see Figure 5). THMs are formed when organic particles (dead bacteria/algal cells) not removed during the filtration process interact with chlorine used to disinfect the water before being distributed to households. The more particles there are, the more THMs are produced. One would expect that levels would taper off in response to stabilized algal abundance; however, levels of THMs continue to increase.

Tributaries flowing into Basin 3 at the southern half of the lake have relatively low concentrations of particles, metals, and nutrients; this area is primarily composed of rural and commercial forestry, with scattered residential development. Residential tributaries flowing into Basins 1 and 2 at the north end of the lake have much higher concentrations of particles, metals, nutrients, and fecal coliform bacteria.

The highest-volume water inputs into the lake are from surface and subsurface runoff (74.6 percent), followed by direct precipitation (19 percent) and water diverted from the Middle Fork of the Nooksack River (6.4 percent). Inputs are approximately the same compared to last year.

Highest outputs from the lake are via Whatcom Creek (79.9 percent), city of Bellingham uses (9.9 percent), evaporation (7 percent), Whatcom Falls Hatchery (2.3 percent), Lake Whatcom Water and Sewer District (0.6 percent) and Puget Sound Energy Co-Generation (0.1 percent). Outputs via Whatcom Creek decreased slightly, but residential water usage increased by 9 percent.

Take Home Message

Similar to the previous year’s findings, our drinking water source continues to decline in water quality, but at a much slower rate than it was in the early 2000’s. Cooler temperatures, especially in the last 6 years, have helped to decrease biological productivity. Concurrently, efforts by the city of Bellingham and Whatcom County to reduce untreated stormwater runoff inputs to the lake from residential areas have probably helped in stabilizing phosphorus levels in the lake. Algal and bacteria levels also appear to be stabilizing. The city of Bellingham’s land acquisition program to purchase undeveloped properties in the watershed has also helped in removing potential development. The city’s increased water fee rate is helping to fund that program, and finances stormwater runoff control measures in the watershed.

The most recent Water Quality Report by the city of Bellingham confirms that our primary drinking water source for approximately 100,000 people in Whatcom County continues to meet or exceed state and federal standards for safe drinking water. The downside is that more of us are reverting to end-of-the-tap water purifiers to make the water palatable. Meeting water quality standards does not necessarily equate to good-tasting water, as the city of Ferndale found out last year when it switched sources of drinking water from the Nooksack River to well water.

Invasive species are a new threat to our drinking water source. Efforts by the city and county to require mandatory boat inspections at public launch sites on the lake will help in controlling their potential introduction into the lake. There is still the danger, however, of introduction from boats launched from privately-owned properties around the lake.

The Whatcom County council also deserves special commendation for its recent decision to approve the reconveyance of approximately 8,400 acres of forested board lands in the watershed, managed by the Washington Department of Natural Resources, back to county control. Utilizing those lands as low impact parklands will reduce the danger of landslides and ensure that surface and groundwater inputs from those areas will not contribute any future contaminant loadings to our drinking water source.

The data from the last few years are hinting that we may be on the path to stabilizing the water quality in Lake Whatcom. Time and continued efforts will tell, but we need to remain diligent for the sake of our community’s health for generations to come.

References

• City of Bellingham. 2013. 2012 Water Quality Report. City of Bellingham, Bellingham, WA. May, 2013. 3 pgs.

• Crosscut.com. 2013. Disaster leads to chance for giant park in Whatcom County. Accessed 05/31/2013 at http://crosscut.com/2009/12/08/bellingham/19428/Disaster-leads-chance-for-giant-park-in-Whatcom-Co

• Harris, W. 2013. No Net Loss – Lake Whatcom: Prognosis Negative. Whatcom Watch, Bellingham, WA. April 2013, pg. 8-9.

• Matthews, R.A., M. Hilles, J. Vandersypen, R.J. Mitchell and G.B. Matthews. 2013. Lake Whatcom Monitoring Program Annual Report Water Year 2011/12. Institute for Watershed Studies, Western Washington University, Bellingham, WA, 369p. Go to www.wwu.edu/iws/, see Lake Studies – Lake Whatcom, Online Reports.

• Schwartz, R. 2013. Officials optimistic on lake cleanup. The Bellingham Herald, Bellingham, WA. March 30, 2013, pg A1 and A6.