Latest Sumas-Blaine aquifer nitrate study sets the stage for large study in 2018

Ecology looking for residents to volunteer their well

The Sumas-Blaine aquifer is part of the larger Abbotsford-Sumas aquifer that extends from northern Whatcom County into British Columbia, Canada. For over 40 years, elevated nitrate concentrations have been documented across the Sumas-Blaine aquifer. The first nitrate study of the area was conducted in 1981. Since then, the U.S. Geological Survey and the Washington Department of Ecology conducted several other studies until 2003, when a long-term regional groundwater monitoring program was put in place.

The Sumas-Blaine aquifer is the main drinking water source for thousands of residents who live in rural areas. Public drinking water systems that rely on groundwater in the Lynden area have also reported high nitrate levels, affecting over 1,000 residents. Recently, some areas have been able to modify their source, which has helped provide water that meets the nitrate standard for drinking water. However, there are still thousands of private wells that are not regularly monitored for nitrate. The city of Lynden uses surface water as a source and does not have concerns with nitrate.

Nitrate in groundwater is a concern because of the risk of methemoglobinemia, or “blue-baby syndrome,” which decreases the amount of oxygen a baby’s blood can carry. Intake of nitrates can also cause specific cancers and birth defects.

In terms of the environment, groundwater contributes to the flow of surface waters in the Nooksack River basin. Nitrate in groundwater is transported to streams, rivers, and eventually ends up in Puget Sound. Elevated nitrate in surface water and marine water can increase the production of algae and decrease dissolved oxygen, which in turn harms fish and other aquatic animals. Studies looking at nitrogen sources reaching Puget Sound from 1995 to 2013 show that, proportional to its area, the Nooksack River puts more nitrogen into the Sound than any other river.

Ecology's Chris Martin records readings from
a well in the Sumas-Blaine area.

This year, Ecology completed the Sumas-Blaine Aquifer Long-Term Groundwater Quality Monitoring report for data collected in 2009-2016. The study targeted wells originally sampled between 2003 and 2005. Samples for nitrate were collected during March of each year. The study focused on the portion of the aquifer that lies in Washington state. Data showed decreasing nitrate concentrations in 9 of 25 sampled wells, no change in 15 wells, and an upward trend in one well.  While there appears to be improvement in the trends for some wells, about one in four wells still did not meet the drinking water standard for nitrate, compared with one in five wells found in a 1997 study of 248 wells.

“While trends are positive in some wells, the sample size in this study is too small for drawing conclusions on the Sumas-Blaine aquifer as a whole,” said Barb Carey, a lead hydrogeologist on the study with Ecology’s Environmental Assessment Program. “Fortunately, more questions could be answered next year when we conduct another, larger repeat study.”

In 2018, Ecology will repeat the broader scale sampling of the 248 wells tested in 1997. Comparing the results will help us determine if there have been aquifer-wide changes in nitrate levels. Ecology also plans to measure water levels in the wells in hopes of tracking groundwater flow in the aquifer.

However, part of the challenge will be getting access to the same wells sampled 20 years ago. Ecology researchers are on a hunt for the original wells in hopes that they can get a better picture of nitrate changes over time. The process is complicated by the passage of time. Many property owners and land uses have changed since 1997.

Ecology's Pam Marti looks over readings from a well in
the Sumas-Blaine area.

The department is looking for help finding these wells and is happy to share the results of the testing with the homeowner. Similarly, if anyone in the Lynden, Sumas, Everson or surrounding area would like to volunteer their well for testing, contact Barb Carey at 360-407-6769, or barb.carey@ecy.wa.gov.

You can read or download the Sumas-Blaine Aquifer Long-Term Groundwater study here: https://fortress.wa.gov/ecy/publications/documents/1703013.pdf