Drew School

On the sixteenth of March in the year 2005 the Marine Biology class went to two points along Old Mill Creek and collected aquatic organisms. On the thirteenth of April in the same year the class went to the same two points and did chemical testing of the water.

The watershed is the land in which all of the water for the area is stored or passes over. This area for the San Francisco Bay Area is quite extensive. It begins with the Sierra Mountains with the snow that collects there. After that there is a river system that takes the water from the melted snow into the bay. When settlers became a little more established they began to make towns and other communal areas near to this elaborate watershed. In these up and coming urban societies there began the exciting world of urban runoff. This term describes the water in the watershed that passes through the cities, towns, and other urbanized areas. In these areas there is of course pollution of the human presence. Common pollutants that are obtained from urban runoff include: oil, gasoline, fertilizers, among other substances. Each of these items causes damage to the bay and the surrounding waterways. The fertilizers for one thing can cause the surface algae to go into a “bloom”. This is when there is so much algae at the surface in a thick mat that the light from the sun above can no longer reach the organisms in the water below. This is an obvious problem for the photosynthetic organisms that live in the now light free zone. Another problem that happens due to these blooms is that the needed oxygen does not get circulated through the water, and as a result more organisms die due to their compromised habitat.

North of San Francisco is the area known as Mill Valley. In this area there are several creeks and streams that join together and eventually emptying out into the Richardson Bay. Around the creeks there is a varying degree of urbanization. Generally the closer to the bay the creek gets, the more urbanized the banks become. Up in the hills there are sections surrounding portions of the creek that are parks and thus rather protected from damage and pollution.

The first creek that we did testing is called the Arroyo Corte Madera Creek. The section of the creek that we did testing was in a relatively urbanized area. In this area there was a large school, several homes, a gas station, and a Whole Foods grocery store. The road the goes over the creek is fairly well traveled. After walking to the end of a parking lot, there is a path that leads to the approximately six foot wide creek. Many houses backed their property against that of the creek. There was even a woman with a young child playing on the bank of the creek.

The other creek was in an obviously less urban area. We did our testing of the Cascade creek on either side of the narrow road leading up the hill. Generously spaced there was only a few residents. While there, very few, one or two, cars passed by. There were several pedestrians that walked by, to and fro from the park. The land surrounding the creek was rock and covered in a healthy amount of trees, moss, and other plants.

Through this field trip, the marine biology class was trying to assess the level of pollution in the streams of Mill Valley. We also wanted to see how the location in relation to urban areas affects the pollution level in the water.

On the first day, when the class collected aquatic organisms, we had to use the following equipment: a D-ring net, buss tub, bug view finder, pipettes, and identification cards. The process of collecting the aquatic organisms begins with finding that perfect point in the creek to do the collection. Areas that are well oxygenated are optimal because then there is a high likelihood that there will be many organisms present. Areas that meet such a requirement are spots called riffles. A riffle is a shallow portion of water that has a disturbed surface, perhaps bubbling over some rocks, so as a result is oxygenated. Once this area of the creek has been located, you take your D-ring and place it down stream from where you are going to disturb the rocks and soil for one minute. You will do this three times at three different points in the creek and after each time, be sure to wash the net of the D-ring out in our buss tub. The Marine Biology class split up in to two groups, so there was a total of six D-ring collections. After the nets are washed after the last collection time, it is time to identify. With your pipettes, suck up an organism and some water to place in your view finder. Using the identification cards, find out what it is that you have in your view finder, and record your findings. Be sure to place the organisms in a separate container after identification, as to keep the count accurate. Ideally this ought to be done until the buss tub is free of organisms, but generally time does not allow. The two groups in the class spent about thirty minutes going through their tubs. After that is complete, be sure to return the water and organisms to the creek.

On the second trip to the creeks to do chemical testing, the class split up into several groups to do the various tests. In my group we did the nitrate testing. There were two tests, the high tech and the low tech. While at the Arroyo Corte Madera Creek we used both tests. The high tech one was more complex then that of the low tech test. In the high tech test we collected about 10 ml of creek water and added a packet that was intended to remove the particles of chromium that were floating around in the water. You must shake the sealed test tube so that the packet fully disengages, then let stand for ten minutes. Once the metal bits settle you ought to be able to see small black specks at the bottom of the test tube. When this is the case you then need to pour the treated water into the second test tube that is provided in the test kit so that the metal pieces remain in the first test tube. Now you need to wash out the first test tube with some water and dump the wash water in a waste receptacle and not back into the creek. Now you are to add a second packet to the treated water, close the test tube, shake until dissolved, and let stand for another ten minutes. While the treated water reacts with the new packet, fill the first test tube, which is now clean and empty, with untreated creek water. Also provided in the test kit is a viewing box and disc. Open the side of the box and place the disc on the post inside. After the viewing box is assembled and the ten minutes has passed you are ready to asses your sample. Place the untreated water in the first slot on top of the box and the treated in the one next to that. Then turn the disc so that the test tubes appear to have the same color. You can then read the level of nitrates in the water from the side of the disc that protrudes from the box slightly.

For the low tech phosphate test we filled a test tube with creek water and added a tablet, labeled “nitrate 1”, to the water and shook until dissolved. Once that happened we then had to add another tablet, labeled “nitrate 2”, to the water and shake until dissolved. This was then set aside to rest for about five minutes. When that is over you are to compare the color of the sample to the colors labeled on the cards in the kit.

Ideally all tests that were done would have produced accurate and logical results, but as science often goes, that was not the case for all parts of the testing. In collecting the organisms from among the rocks, there are several sources of error, which in turn could change the results of the collection. The most prominent and obvious is that when people were identifying the organisms they miss identified them based on the drawings on the cards. Another source of error that might have changed some results is that not all organisms were caught and washed out of the net, and thus could not be counted.

Despite the probable sources of error, the results seem to represent a very healthy creek. Based on the various indicator species that we found in the creek, Mayflies for example, the water appears to be rather unpolluted thus allowing the sensitive to live and growing there. There was actually a hearty amount of Grade One organisms collected in all the areas of testing. This then implies that the creek was not only in good health at the time of testing, but is in rather continuous good health; thus resulting in such a high population of the sensitive organism. The presence of the Grade one organisms undoubtedly means that there is going to be organisms that fit into the other two less sensitive groups present in the creek as well.

When the class went to the creeks the second time to do the chemical testing, many of the tests did not produce the expected results for various reasons. For the high tech nitrate test, not all of the substances in the packets that we added to the sample of creek water might have made it in to the test tube, thus not resulting in enough of a reaction to produce the needed colors to read the test. On the flip side there might have been too much water for the packets. Of course while pouring out the non-chromium water sample, some particle of the metal could have made it into the secondary test, and as a result affect the out come of the test. The additives may not have dissolved all the way to begin with. All of these things in conjunction or independently could have resulted in the tested water not producing any color to compare to the colored disc.

For the low tech test, the amount of creek water tested might not have been exactly appropriate to work effectively with the tablets that were added. In addition to that the tablets had crumbled in their casing, thus making it difficult and uncertain if all of them were put into the test tube. Another cause for error involving the test tablets is that they had expired just before the testing took place. This in turn could have caused them not to react at all or react completely differently then expected with the water sample. Had the water turned a color we would have matched it to one of the colored boxes on the reference card. But unfortunately the card was incomplete. The second box had not color in it; this could have been for many reasons, sun exposures or faulty printing. As a result, the group being unable to read the color that did not appear in the sample anyway.

The overall class data was filled mainly with values that either varied extensively, or were unable to be collected. Both the pH test produced data that was believable when looked at separately. But once compared, the paper test and tablet test results showed quite different things about the water condition. According to the paper the pH in Cascade Creek was 5, while the tablet test had a pH of 7.5. This variation of two and a half increments on the scale is the difference between an acidic creek and a slightly basic creek. For the dissolved oxygen test it is difficult to know how well the tests worked because the two are measured in different units, hence making it quite hard to compare the two. Both the phosphate and nitrate tests did not work well enough to have a result collected. Turbidity, how much floating debris is in the water, test is also hard to judge on a wider scale, but the values seem to reflect logic. There was a lower reading at a higher elevation where there was less of a chance for sediment to collect in the water. Where as there was a higher reading in the water of the lower elevation which was able to travel over longer distances and as a result collect more sediment. Temperature reflects the change in elevation and increase shade coverage that went along with the more rural land; where the lower elevated creek had a warmer temperature. The last test that we did was the salinity test. Again relating to elevation, the higher sections of the creeks have a more concentrated supply of water that is melting from even higher regions and water that is less polluted as it travels to the creek. In the low elevation, all of the salt, among other pollutants, washes into the water and accumulates with the addition of more pollutants and more slightly polluted water. This is supported but the data that we collected; a level of 2ppt in the lower Arroyo Corte Madera Creek and a level of 1ppt in the higher elevated Cascade Creek.

Mill Valley Watershed Stream Assessment Report

Jennifer Curto

Dates:

March 16^th and April 13^th 2005

Introduction:

In our stream assessments we visited two different parts of the Northern California Watershed. First off, a watershed is land where water and sediment drain into a common body of water. This water usually originates from rainfall which gathers at high elevations and flows downward. In order to understand the way in which a watershed works, it is first important to understand the basics of the water cycle. When it rains, precipitation is occurring, and liquid falls to the ground. Eventually it will gather and flow into streams, creeks and rivers. As the water continues to flow to areas of lower elevation, some water will become evaporated and it will condense in the atmosphere. However, the streams, creeks and rivers that continue to flow are meanwhile being introduced to run off. Run off occurs when any amount of water is released into an environment in unnatural ways. There are two main types of run off, rural run off and urban runoff. Rural run off occurs when water used to grow plants, or animals “runs off” into the natural water flows of the watershed. This usually pollutes the water because along with plain H2O, sediment, pesticides, fertilizers, animal waste, and antibiotics are also released into the water. The second type of run off, Urban run off, is even more harmful to the environment. It occurs when water used for industrial or human purposes is released into the natural watershed. This water usually contains toxic substances such as motor oil, paint, and detergents. It also contains substances such as pet waste, and construction waste (dirt). All of these different things being released into the water from various types of run off are extremely detrimental to the environment which the watershed impacts.

Location Information:

For this assignment on Stream Assessment, our class collected our data at two points along one creek. This creek is called the Arroyo Corta Madera Creek located in Northern California in the San Francisco Bay Area. More specifically, the creek is located in Marin, a suburb of San Francisco. To get to Marin, it is only a twenty minute drive across the Golden Gate Bridge. The creek flows down through the more mountainous hills of Marin, and eventually flows through Mill Valley, and into the Richardson Bay. This area of water is directly connected to the San Francisco Estuary which leads to the Pacific Ocean.

The first point at the stream that we visited was an urbanized area of Mill Valley. The Stream itself seemed to appear magically amongst the parking lots and strip malls. Regardless of the urbanization, the banks of the steam where heavily vegetated, and trees were present for providing shade. The stream was lined with backyard fences, and a narrow grassy area separated the water from the wood of these fences. In some areas of the stream, sharp muddy banks were supported by man-made wood blockades. In other areas it was concrete that acted as a bank. However, there were also areas of the stream where grassy gravel sloped down to the water. The entire area was fairly shady, it somewhat resembled a swamp. Lastly, a small trail wove along the water which displayed the human presence.

In order to collect out data, we used a combination of materials provided by both Britta and Ms. Lacks. The first time we visited the sights we were testing for water quality by counting aquatic insects. Therefore, our goal was to collect as many insects as we could. The way in which my group collected insects was by using a D-ring net. This type of net is shaped like a D and it works well because we could lay the flat edge against the bottom of the creek. So, we had the very brave Olivia enter the water and gently plant the D-ring net into the creek bottom with the entrance of the net facing upstream. In choosing a spot to place the net, we decided on an area with riffles. Riffles are shallow areas where tiny little rapids form. This causes more oxygen to dissolve into the water; therefore, insects are more likely to be found in these areas. Anyhow, after we picked a spot, Olivia leaned forward and agitated the creek bottom directly upstream from the net opening. After a minute of agitation, several insects had flown into our net along with some debris. We then gently dumped these insects into a tub of stream water. Next, we used a large turkey baster to suck up the insects in our bin one at a time. We then squirted them out into little dishes with magnifying glasses attached so that we could see the insects in detail. After we got a good look at our creatures we checked out our species identification cards that told us what these insects were. After we spent 30 minutes identifying species we made note of our data and released the insects. We did the exact same procedure at the second sight upstream at Cascade Falls.

During the second trip we took to the creeks in Mill Valley we collected different types of data about the water. This time we used more scientifically advanced methods of assessing the streams. Our class divided up into pairs and each group got a test or two to complete. My group did the Nitrates test. This consisted of taking a sample of the creek water in a test tube and adding a pill-like powder tablet to the sample. After it dissolved we added another tablet and awaited a color change in the test tube which would tell us our results. The other groups performed similar tests. However, some groups tested things like salinity and turbidity, still using scientific equipment. We then performed the same tests upstream at Cascade Falls.

Data:

This chart represents the quantity of insects we collected on our first trip to the streams.

Down Stream, Arroyo Corta Madera Creek, Whole Foods

Up Stream,

Arroyo Corta Madera Creek,

Whole Foods

Cascade Falls

Up Stream

Cascade Falls

Down Stream

Mayfly-16

Stonefly-2

Penny-2

Mayfly-39

Stonefly- 3

Mayfly- 12

Stonefly -2

Mayfly- 16

Stonefly- 1

Caddisfly- 1

Riffle Beatle- 1

Sowbug-5

Scud- 8

Sowbug-10

Scud-1

Dragonfly -1

Aquatic Worms- 36

Aquatic Worms- 15

Black Fly Larvae- 1

Aquatic Worms-15

Aquatic Worms -3

Group 1 are organisms that are pollution sensitive. They are only found in clean water.

Group 2 are organisms that are somewhat tolerant of polluted waters.

Group 3 are organisms that can exist in water of any quality, good to bad.

The next chart represents the data we collected from our second trip to the creeks.

Arroyo-Corta Madera Creek. Near Whole Foods.

Cascade Falls.

Up Stream.

PH Paper

PH Tablet

7.5

Dissolved Oxygen Hi-tech

12 mg/l

13 mg/l

Dissolved Oxygen Low-tech

1 ppm

3 ppm

Phosphate

Nitrate

Salinity

2 ppt

Turbidity

Temperature

12 degrees Celsius

Analysis:

Regardless of the various chemical tests which seemed to have failed, we learned a lot about the water by testing for salinity, dissolved oxygen, temperature, and turbidity. Considering the difference in surroundings between the two creeks, it is obvious why the Cascade Falls site appeared to have half the turbidity of the Arroyo-Corta Madera Creek. Cascade Falls is less subject to run-off and excess sediment; therefore, the water seemed clearer, and our tests proved us correct. It also makes sense that both of our dissolved oxygen tests showed more dissolved oxygen at the Cascade Falls site. At this site the creek is steep and the sharp rocks create small rapids. This agitation of the water allows for more oxygen to dissolve into the water. In terms of temperature, it does not surprise me that the two creeks were the same. They both had vegetation which supplies the sites with optimal shade. Last but not least, our salinity tests showed that the two creeks had the same salinity. This is slightly surprising to me because Cascade Falls seems to be at a higher elevation than the Arroyo-Corta Madera Creek. Therefore, I find it hard to believe that any salt water would make it up stream that far.

Besides the informative data that we collected, the most educational part about this trip to me was gaining an understanding of how scientists go about assessing a stream. I would have never thought to use insects to test the water quality. In addition, I did not even know that there were that many bugs in the water AHH. On a different note, I do admit to becoming slightly frustrated with some of the testing. It was a little lengthy, and I was upset that out tests did not work. Yet in the bigger picture, I always prefer hands on observing to classroom notes!

Tub	1A	1B	2A	2B
Location	Downstream on the Arroyo Corte Madera Creek, near the Whole Foods	Up stream on the Arroyo Corte Madera Creek, near the Whole Foods	Up stream on Cascade Creek	Downstream on Cascade Creek
Group 1 insects àpollution sensitive, only found in clean water	Mayfly – 16 Stonefly – 2 Water penny - 2	Mayfly – 39 Stonefly - 3	Mayfly – 12 Stonefly – 2	Mayfly – 16 Stonefly – 1 Caddis fly – 1 Riffle Beetle
Group 2 insects àsomewhat tolerant to pollution	Sow bug – 5 Scud - 8	Sow bug - 10	Scud – 1 Dragonfly larva - 1
Group 3 insects àcan live in most any water quality	Aquatic worms – 36	Aquatic worms – 15 Black fly larva - 1	Aquatic worms – 15	Aquatic worms – 3 Midge fly – 2

Tests	Site #1 (A.C.M. Creek)	Site #2 (Cascade Creek)
pH Paper	6	5
pH Tablet	7	7.5
Dissolved Oxygen (high tech)	12 mg/L	13 mg/L
Dissolved Oxygen (low tech)	1 ppm (lower)	3 ppm (higher)
Phosphate	0	0
Nitrate	0	0
Salinity	2 ppt	1 ppt
Turbidity	~ 10 jtu	~ 5 jtu
Temperature	12 º C	10 º C