What We Test

We conduct monthly and quarterly stream testing and annual BIBI testing. (For information on BIBI testing, see below.)

Monthly/Quarterly Stream Testing

Our regular stream testing consists in large part of collecting small samples of stream water, adding various testing chemicals, and observing the results—for example, adding drops until a purple liquid turns clear. We also take samples for biological testing, measure stream and air temperature, and obtain other data. We work in small teams using a kit that contains all chemicals and equipment and complete instructions. There is always a certified stream tester on each team.

Eight times a year we test two sites. A single team visits 1 site on McAleer Creek and 1 site on Lyon Creek. We call this our “monthly testing.”

Four times a year, we test four sites. There are two teams, and each team visits 2 sites on McAleer Creek and 2 sites on Lyon Creek. This is our “quarterly testing.” When we test 2 sites on one stream, we can compare values at a site near where the stream enters our city and values close to Lake Washington. This tells us what pollutants the stream picks up within Lake Forest Park.

These are the variables we test for:

Temperature: Salmon and many other fish require cold or, at least, cool water. This is why shady stream banks are beneficial.

The preferred temperatures vary by species, season of the year, and other factors. Temperatures greater than 21⁰ Celsius in the warmer months have been shown to affect migratory patterns of salmon. One important reason why cold water is important is that stream temperature has a direct correlation with the dissolved oxygen (DO) and oxygen saturation.

Dissolved Oxygen (DO): Aquatic plants and animals need oxygen.

The Washington State Department of Ecology DO threshold for a healthy stream is 8.0 parts per million. Moving water and cool water hold more dissolved oxygen than still water and warm water. Dissolved oxygen is also reduced by bacteria. From DO and stream temperature, we calculate the oxygen saturation of our streams. Oxygen saturation is the amount of oxygen in the stream as a percentage of the maximum amount that is possible given the current stream temperature (and atmospheric pressure). 

Alkalinity: Alkalinity protects water against changes in pH, making it more stable for aquatic life.

Alkalinity is a measure of buffering capacity of water. Alkalinity “protects” pH status with two-way reactions with acids and bases, helping to minimize their impact on pH. If acid goes up the reaction goes basic and vice versa.

Hardness: Hardness is a measure of the amount of dissolved calcium and other minerals.

The primary dissolved mineral in stream water is calcium carbonate. Water may be hard for natural reasons such as limestone stream beds but may also be hard due to human activity. Therefore hardness can be used to measure the influence of human activity in the watershed. Much like human beings, fish need calcium and other minerals. Hardness below 15 mg/L or above 200 mg/L may be harmful to fish and other aquatic organisms.

pH: pH is a measure of the level of acidity or alkalinity.

A pH of 7.0 is neutral. Water with a pH below 7 is acidic, above 7 is basic. A pH of 7 to 8 is best for fish. 

Turbidity: Turbid water is cloudy. Of course, clear water is better.

Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, like smoke in air. High turbidity can prevent light getting to lower depths, inhibiting the growth of plants and the fish and invertebrates that depend on them. In addition, high turbidity can inhibit gills’ ability to absorb DO.

Coliform Bacteria: These bacteria come mainly from the intestines of mammals and birds. E. coli is a potentially dangerous type of fecal coliform bacteria.

Fecal coliform bacteria in local streams results from the excrement of humans, livestock, wildlife, and dogs and cats. Because E. coli bacteria are live organisms, specific conditions, such as winter rain run-off, can quickly increase the E. coli count. Negative conditions such as cool water, aeration, and even direct sunlight can decrease E. coli.

BIBI Testing

Once a year, we conduct BIBI testing. “BIBI” is short for Benthic Index of Biotic Integrity. “Benthic” refers to the stream bottom. BIBI testing and other tests of biotic integrity are well-established procedures in environmental science.

BIBI testing entails collecting samples of stream sediment and very carefully picking out bugs and bug parts with tweezers. By “bugs,” we mean insects and other invertebrates. Then a professional entomologist conducts further analysis and provides a scientific rating of the health of our two streams based on how many bugs and which bugs are present.

Again, no experience is necessary to participate. The work is surprisingly enjoyable. You get close to nature and become “intimately” familiar with our streams.

BIBI testing was developed by Dr. James Karr, of the University of Washington.

Updated 3/21/2018