Of course, by definition, river flows down from high to low land. It means, when it meets with forests, it runs through different kinds of forests at each altitude. Yadoriki Water Source Forest やどりき水源林 is one of the beginnings of Sakawa River 酒匂川. The forest spreads over steep slopes of Western Tanzawa 西丹沢, whose soil consists often of gravels of green tuff and scorias, i.e. not so fertile. Yadoriki Stream 寄沢 is narrow when it shines, but steep and rocky slope of Western Tanzawa mountains make the flow rapid torrent. Riverbed is made of rocks that could be large. Basically water of Yadoriki Stream is cold even if we’re in high summer.
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| A typical scenery of Yadoriki Stream |
The way to collect specimen from Yadoriki Stream is also place-specific. When we study aquatic lives there, we position the mouth of our landing net facing to the upstream and kick rocks and gravels at the shallow bottom of the stream. The creatures clinging to the stones are washed away by fast flow and captured in the net. The living things we can collect from such environment are peculiar bunch. Normally, we cannot meet them in lower part of the same river, where it is wider with lots of warmer water and the flow is slow at least comparatively. In my post on June 10, I showed you we collected these creatures in early summer this year from Yadoriki Stream:
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| Kajika frog (tadpoles) |
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| Kamimuria quadrata |
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| Perissoneura Paradoxa |
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| Epeorus latifolium |
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| Planarian Flatworms |
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| Oyamia gibba |
Kanagawa Prefecture gives scores for each of these creatures. The numbers are adjusted to Kanagawa’s river from the Japanese Biological Monitoring Working Party (BMWP) published in 2017 from the Ministry of Environment. Japanese BMWP itself is modified for Japan based on English version started in 1976. So, Kanagawa’s number is mixed race grandkids of original Brits. With this benchmark,
- Kajika frog and Planarian Flatworms are Indicator species for very clean stream of water source area.
- Kamimuria quadrata, Perissoneura Paradoxa, Oyamia gibba and Epeorus latifolium earn score 9 which is the second highest mark for the monitoring score.
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| “Please put your pen on the desk …” |
The way to calculate the grade of the river based on the observation is summing up the numbers each creature earns, then divide the total by the number of species we’ve encountered. In today’s example, let’s spare indicator species for this calculation (; they have already earned perfect score as an indicator). We do the math like
(Kamimuria quadrata’s score + Perissoneura Paradoxa’s score + Oyamia gibba’s score + Epeorus latifolium’s score) / (Number of species in this equation, i.e. 4)
= (9+9+9+9) / 4
= 9
Perfect score is 10, which says the stream has impeccable quality. 9 is the second highest grade. Yadoriki stream in June 2022 showed A-student result for water quality exam. We Water Source Monitoring Volunteers do our study up to this point and report our findings to Kanagawa Environmental Research Center. The researchers at the Center tally annually our findings and make the result public. The latest report for Sakawa River is for 2019 which is downloadable from here. This fiscal year’s deadline for reporting to the Center is early January. We’re in a final stretch now.
We can choose the point of a river to monitor according to our preference, as long as the water is in either Sagami 相模川 or Sakawa River System. (The project is to monitor water quality for daily use of people in Kanagawa, paid by taxpayers, mate.) I happen to be a Forest Instructor commuting to Yadoriki Water Source Forest periodically. In addition, we Forest Instructors do such study in Yadoriki Stream for years. So, studying Yadoriki Stream with landing nets and plastic bats is … a bit of boring. But in this project, the Research Center gives us trainings in different point of a river, like in a middle basin, or far smaller water source in a forest of agricultural area, similar to Niiharu Citizen Forest 新治市民の森. (Niiharu Forest is in the system of Tsurumi River 鶴見川 that is not a source for potable water. So, the place is not covered in this project.) The way to collect creatures in these places is a bit different from that in Yadoriki. Next week, I tell you my adventure in such environment.
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| Grade sheet! |
We can choose the point of a river to monitor according to our preference, as long as the water is in either Sagami 相模川 or Sakawa River System. (The project is to monitor water quality for daily use of people in Kanagawa, paid by taxpayers, mate.) I happen to be a Forest Instructor commuting to Yadoriki Water Source Forest periodically. In addition, we Forest Instructors do such study in Yadoriki Stream for years. So, studying Yadoriki Stream with landing nets and plastic bats is … a bit of boring. But in this project, the Research Center gives us trainings in different point of a river, like in a middle basin, or far smaller water source in a forest of agricultural area, similar to Niiharu Citizen Forest 新治市民の森. (Niiharu Forest is in the system of Tsurumi River 鶴見川 that is not a source for potable water. So, the place is not covered in this project.) The way to collect creatures in these places is a bit different from that in Yadoriki. Next week, I tell you my adventure in such environment.
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| Our tools for water monitoring |
If you find environmental issues in waters of Kanagawa Prefecture, please make a contact with Kanagawa Environmental Research Center 神奈川県環境科学センター
1-3-39 Shinomiya, Hiratsuka City, 254-0014
〒254-0014平塚市四之宮1-3-39
Phone: 0463-24-3311
FAX: 0463-24-3300
k-center@k-erc.pref.kanagawa.jp
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