Since September 27, the Friends of Marsh Creek Watershed have been working with local stakeholders to identify what caused more than a 100 dead fish within Marsh Creek and admit that the cause of the deaths will likely remain unsolved.
Staff and volunteers went out to investigate and were able to observe over 100 dead fish from just above Delta Road going all the way downstream past Creekside Park in Oakley. The organization made contact with authorities according to their Surface Water Ambient Monitoring Plan with the Central Valley Regional Water Quality Control Board and our Quality Assurance Plan with the Environmental Protection Administration.
Diane Burgis, executive director of the Friends of Marsh Creek, explained in a Press Release that results from the carcass and water samples collected that day came back negative for both organophosphate and pyrethroid pesticides. Since there were no other indicators at the time of other specifics chemicals to test for there were no other tests conducted on the samples. In other words since we saw no presence of a chemical spill authorities did not know what to test for. Testing for a cause of the fish kill is inconclusive except we can exclude pesticides.
“It’s common for the cause of fish kills not to be solved. The best thing to do is to report something as soon as you see something or think something may be wrong to the police,” said Burgis. “Also notify the Friends of Marsh Creek Watershed so we can work quickly to capture samples.”
In this particular case, Burgis says they do not know the exact timeline of when the fish were killed but did say that within two-hours of being notified of the dead fish they were on scene for testing.
In speaking with other experts, she explained that only a small percentage of fish kill event cases are resolved.
“In order to identify the cause we have to know what we are testing for,” said Burgis. “In order to know what we are testing for we need to be able to observe other conditions that could be contributing to the fish kill like seeing sheens or other indicators of spills, smelling something off the creek or seeing something dumped in the creek that could have chemicals in it. Since we didn’t get reports of any of that at the time of the fish kill we were unable to determine any other things for the water samples and carcass samples collected to be tested for.”
According to the release, often a fish kill in late summer is related to Dissolved Oxygen issues. Many people involved in the investigation suspected this to be the case in this fish kill however there is no way to test for that as we would have had to test the water at the time the fish were dying to have been able to conclusively blame dissolve oxygen as the culprit. Further if you look at the picture above from the day of the investigation you will see what looks like bleeding from the eyes the gills and other orifices. That seems to indicate some sort of a chemical poisoning.
Days following the fish kill FOMCW received calls from people that live near or walk on the trail regularly. A couple people let FOMCW know that they had seen a sheen up near Homecoming Park around the time of the fish kill. Unfortunately they were notified after the fact and had no way of investigating it.
“At this point it looks as if this will be an unsolved fish kill,” said Burgis. We have had five fish kills in the last 10 years as far as we know only one of those authorities were able to figure out the cause. We do know that there appears to be an unusual amount of water that was released in to the creek at the time around the fish kill (even accounting for the rain event that occurred a day or two before).” Friends of Marsh Creek Watershed is working on identifying why Marsh Creek gets these significant amount of water flowing in the creek at times for no reason.”
Information provided by Friends of Marsh Creek Watershed
For more information about Fish Kills in the past, water monitoring and FOMCW’s response plan please join us for our meeting Thursday October 23rd from 6:30 to 8:30PM. We will have Mark Boucher PE, Chief Hydrologist from Contra Costa County Flood Control and he will talk about the peak flows and how they can determine how much water is flowing in Marsh Creek at anytime. We will also have Brian Curran, Chairperson of the Monitoring Committee and Mary Helen Nicolini one of our newest volunteers who was onsite during the fish kill and who happens to be an Aquatic Biologist.
Meetings are held at
Liberty Union High School District Offices
located at 20 Oak Street, Brentwood, Ca
