Field Notes

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Hill Slough: 2025-06-10 08:30:00 (DOY 161)
Author: Joe Verfaillie
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Summary: Replace gate lock, low tide, 7700 reservoir empty, RSSI 0 - fixed,SHF plate exposed - reburied, shadow band stuck - restarted

Hill Slough
2025-06-10

I arrived at about 9:30 PDT. It was cool and super windy as usual. Tide was low - the channel staff gauge read about 3.75ft at 8:37PST. The Eosense CO2 probe was blowing in the wind, the HYDROS21 was stuck in the mud and the miniDot was just barely in the water.

I removed the latch and combo lock from the gate and replaced it with a heavy chain and new lock - same combo.

At the tower the wash reservoir was completely empty - I refilled it. The tubing had come loose inside the box. I put the tubing back on the barb and added a small zip tie. Later I tested the spray and it seemed to hold.

I downloaded the met, flux and camera data. I cleaned the eddy sensors and radiometers.
The 7500 read: 418.3ppm CO2, 639.2mmol/m3 H2O, 16.6C, 101.5kPa, 98.9SS - 99.8 after clenaing
The 7700 read: NA ppm CH4, 0.0RSSI - 1.99ppm CH4, 72 after cleaning.
When I tested the wash and spin the RSSI climbed to 83.4

The value on the pore water sipper wasn't working and the syringe I had was poor but I manages to get a water sample. The sipper needs a new valve next time.

Porewater, 5.74mS, 18.1C

The shadow band was stuck again, I tweaked the power control knob again and it was spinning maybe too fast. I need to buy more parts if I want to swap this one out.

SHF plate #1 had become exposed due to erosion. I put waders on but didn't really need them as the ground around the tower is very firm. I reburied the SHF plate in a high area that looked less likely to erode soon. The blue sticker on the underside of the plate had a bubble of water trapped under it. I should have probably cut the bubble and deflated it but didn't. The soil and water was warmer than my fingers.

On the way out I dropped a bag of cable ties near the beginning to the board walk next to the channel. Here the mud was shin deep and tried to suck the boots off my feet.

I left at about 10:27 PDT

2 photos found

20250610HS_NewGateLock.jpg ( 2025-06-10 10:22:55 ) Full size: 1920x1440
New chain and lock to secure outer gate