Lake Whatcom Status: When Flatlining is A Good Thing

April Markiewicz is the associate director and toxicologist in the Institute of Environmental Toxicology at Huxley College of the Environment at Western Washington University, as well as the chair of the city’s Lake Whatcom Watershed Advisory Board and president of the People for Lake Whatcom Coalition.

Almost 50 years have passed since water quality monitoring studies first began of Lake Whatcom, the primary drinking water source for all of Bellingham and half of Whatcom County residents. Those studies have provided indisputable evidence that the lake’s water quality has been steadily declining, and in recent years getting worse at a faster rate (Matthews et al. 2006). They have also shown that as of 2005, water quality degradation has spread beyond the two shallow northern basins and into the largest, Basin 3, that contains 96 percent of the water. As a result, the entire lake is now affected.

The most recent study, however, indicates that the decline may be slowing down, and for some water quality parameters either remaining unchanged (flatlined) or slightly improving (Matthews et al., 2010).

Dr. Robin Matthews, director of the Institute for Watershed Studies (IWS) at Western Washington University, and her colleagues collected water quality data in all three basins of Lake Whatcom (Map 1) from October 2008 through September 2009. She has been collecting these data since the mid-1980s with support and funding from the city of Bellingham and making those results public in annual reports. A synopsis of the 2008/09 Lake Whatcom Monitoring Program Annual Report results are as follows:

Surface water temperatures in all three basins were exceptionally warm in August, exceeding all previous records since 1988.

Total phosphorus (TP) levels continue to increase in all three basins, with levels in Basin 3 now exceeding those in Basin 2 (Figure 1).

Green and blue-green algae numbers were higher than 2008 levels throughout the lake (Figure 2).

Blue-green algae continue to outnumber green algae and are steadily increasing in all three basins (Figures 2 and 3).

Chlorophyll concentrations, an indicator of primary productivity, were about the same or slightly higher in all the basins (Figure 4).

Dissolved oxygen (DO) levels in the bottom waters of Basins 1 and 2 decreased from 12 mg/L to < 1 mg/L by early September. Levels in the northern portion of Basin 3 were < 3 mg/L (Figure 5).

A significant trend is developing in pH levels with minimum annual pH levels becoming lower (more acidic) and maximum annual pH levels getting higher (more alkaline) due to greater biological productivity throughout the lake. (Figure 6).

Dissolved inorganic nitrogen (DIN) levels decreased in all three basins during the summer months creating nitrogen-limiting conditions that favor blue-green algae growth (Figure 7).

Looking at each graph it is important to remember that each point represents one year’s worth of data. Variations from year to year are not only a function of the amounts of nutrients entering the lake, but also the responses of the lake’s biological organisms to those nutrients under changing environmental conditions, including temperature variations, wind patterns, cloud cover and water currents, as well as interactions within and between species (competition/predation).

For example, warmer temperatures during 2003-05 served to increase biological productivity in the lake, speed up thermal stratification in Basins 1 and 2, lengthen the time that the deeper sections of the lake were without oxygen, prolong the time that sediment-bound phosphorus and other pollutants could be dissolved and released back into the water and accelerate nutrient cycling throughout the lake.

Conversely, below normal cooler temperatures in 2007 and 2008 resulted in the opposite effects. Moreover, besides slowing algal growth, the colder temperatures changed species dominance by affecting the less-cold-tolerant blue-green algae, allowing green algae to dominate (Figure 2).

In 2009, temperatures were back to typical levels, except in June and August when temperatures soared and set new records in the lake. Similar to conditions during 2003-05, biological productivity increased, as indicated by algal numbers and chlorophyll concentrations, causing other parameters like DIN or DO in the bottom waters to decrease. So evaluating data over the short term can be highly informative in explaining why there is variability in the data from year to year.

To reveal long-term trends or patterns from the year to year variability in the data requires at least 10 years of data if not longer depending on the relationships and processes being evaluated. With almost 50 years of data, we know that water quality in all of Lake Whatcom is impaired and that it has been degrading at an accelerated rate in the last 20 years.

The trends in the data for the last 5 years have been more encouraging, showing that for some of the water quality indicators the data have stayed relatively unchanged (or flatlined, according to Matthews) or are trending downwards. Moreover, even those data that are still trending up seem to doing so at a slower rate of increase (Matthews pers. comm., 2010; Matthews et al., 2010).

Though phosphorus levels have indeed increased in all three basins due to nutrients still entering the lake from the surrounding watershed, the good news is that since 2003 those levels appear to be staying relatively unchanged or slightly decreasing over time. This may indicate that stormwater runoff treatment measures implemented by the city of Bellingham and Whatcom County over the last few years are actually reducing nutrient loading to the lake.

Green and blue-green algae have also increased in all three basins; however, like phosphorus, when compared to data from the last five years, their numbers have also been trending downward, though they are still far above what they were even 10 years ago (Figure 2). Not surprisingly, chlorophyll, which is an indicator of total algal biomass and therefore of the biological productivity in the lake, has also been staying relatively unchanged over the last 5 years in Basins 2 and 3 (Figure 4). Moreover, even in Basin 1 where the chlorophyll level is higher than last year’s, it is still less than what it was in 2007.

In a recent presentation to the North Cascades Audubon Society, Matthews presented these encouraging results. She also reiterated that the water quality in Lake Whatcom has not improved; it just has not degraded at the same rate as it was in the past and may be in the process of stabilizing. She reemphasized the need for continued long-term studies to determine whether the trends in the data are real or just part of the natural variability inherent in ecological systems.

Matthews was cautious in her assessment of the current status of the lake because of other trends in the data she is seeing. One trend is the increased variability in pH (Figure 6) throughout the lake. Annual minimum pH values are getting lower (becoming more acidic) and maximum pH values are getting higher (more alkaline). This is due to increased biological productivity creating more oxygen during the day which increases pH levels resulting in the consumption of more oxygen for respiration and decomposition at night that lowers pH. These data indicate that biological activity is continuing to increase in all basins.

Another trend is the continued decline in DIN (Figure 7). As a nutrient used for growth, when DIN becomes depleted it causes green algae to become nutrient-limited. Since blue-green algae can use nitrogen from the air as an alternate source, they continue to grow throughout the summer and become the dominant species. Low DIN therefore creates favorable conditions for blue-green algae growth and has facilitated their increased abundance throughout the lake. These algae are considered a nuisance species because of the slimy and sticky mucus coatings that enable them to form large mats in the water column as well as create odor and taste problems in drinking water.

Matthews et al. (2010) report that it was these algae and certain diatoms that caused the City’s water treatment filters to clog very rapidly in 2009, resulting in a mandatory restriction on water use throughout the community. This problem will only get worse given the current trends.

In the last few years, Matthews has begun to speculate, based on the trends in the data, that the rates at which conditions have been degrading in the lake may be slowing down, at least in the short term. The 2009 data provide further evidence that conditions in the lake may be stabilizing; however, she emphasized the need for many more years of data to confirm these trends she is finding. She also pointed out that the data are not indicating that the lake’s water quality is getting better, only that it is not getting worse for now.

This decline in the water quality of Lake Whatcom did not manifest itself in just the last 21 years. Data collected in the mid-1960s by the newly created Institute for Freshwater Studies (now IWS) showed that water quality was already declining in Basin 1. The results were not too surprising, given that most of the early residential development was located there (Geneva Consulting, 2008).

Though concerns were raised at that time about the future of the lake, development was allowed to continue. In 1998 the lake was listed as an impaired water body under section 303(d) of the Clean Water Act.

Twelve years have elapsed since then and the water quality has further deteriorated, as evidenced by the ongoing monitoring studies. Today there are approximately 6,800 households in the watershed with the potential for 1,945 more to be built (Rexroat pers. comm., 2009). The consequences of allowing that development will be costly to our community.

Community leaders implemented some measures over the years to protect the lake, especially as subsequent studies indicated the lake’s continued decline in water quality. Those efforts, however, were sporadic as our community’s economic and political priorities changed over time.

We no longer have the luxury of doing nothing, taking our time, or ignoring the problem. State law (RCW 90.48.080) prohibits “…any person… to cause pollution of state waters…” Moreover, any waters that are polluted and subsequently listed under section 303(d) of the Clean Water Act must be cleaned up to meet state water quality standards by the person or persons responsible. Since we as a community allowed the lake to become polluted, we are charged with cleaning up and restoring it, regardless of whether we use it as a drinking water source or not.

According to the draft Total Maximum Daily Load (TMDL) study for Lake Whatcom 74 percent fewer acres of development in the watershed are required to return phosphorus loadings to natural loading levels (Pickett and Hood, 2008). That means at least 3,000 of the 3,600 acres in the watershed that are currently developed need to be removed to meet the goal of 524-563 acres allowed in the TMDL (Pickett and Hood, 2008).

The full participation, leadership and support of our community leaders are needed more than ever to help us as a community achieve those limits. Our personal health and safety, as well as the long-term sustainability of our community are dependent on the next steps we take together to clean up and restore our drinking water source. §

Note that figures referenced here are only shown in the hard copy edition.

• Geneva Consulting. 2008. Lake Whatcom Watershed – A Retrospective Resource Directory 1850-2007. Resource Directory prepared for Whatcom County Public Works, Stormwater Division by Geneva Consulting, Bellingham, WA., March 25, 2008. 47pp.

• Matthews, R.A., M. Hilles, J. Vandersypen, R.J. Mitchell and G.B. Matthews. 2010. Lake Whatcom Monitoring Program Annual Report Water Year 2008/09. Institute for Watershed Studies, Western Washington University, Bellingham, WA, 351p. Available online at http://www.ac.wwu.edu/~iws under Lake Studies - Lake Whatcom Online Reports.

• Matthews, R.A., M. Hilles, J. Vandersypen, R.J. Mitchell and G.B. Matthews. 2006. Lake Whatcom Monitoring Program Annual Report Water Year 2008/09. Institute for Watershed Studies, Western Washington University, Bellingham, WA, 465p. Available online at http://www.ac.wwu.edu/~iws under Lake Studies - Lake Whatcom Online Reports.

• Pickett, P. and S. Hood. 2008. Lake Whatcom Watershed Total Phosphorus and Bacteria Total Maximum Daily Loads Volume 1: Water Quality Study Findings. Publication No 08-03-024, November 2008. Washington Department of Ecology, Olympia, WA. 145 p. Available online at http://www.ecy.wa.gov/biblio/0803024.html

• Rexroat, L. 2009. Watershed Buildout Potential. Spreadsheet provided to the Lake Whatcom Watershed Advisory Board by L. Rexroat, property acquisition specialist, City of Bellingham.