Bridgeport Lakes Mono county

Freshwater Harmful Algal Bloom Warning For Crowley Lake and Bridgeport Reservoir Dam

Written by sierrarecmagazine

Crowley Lake; Hilton Creek Drainage Receives a Warning For Toxic Algal Bloom As Bridgeport reports as Dangerous

September 2, 2021 – The California State Water Resources Control Board issued a warning this week for Crowley Lake / Hilton creek Drainage for Algal Bloom. They also upgraded the Bridgeport Reservoir near the dam as dangerous.

Advisory Recommendations: NO SWIMMING. Stay away from algae and scum in the water. Do NOT let pets go in the water, drink the water, or eat scum on the shore. Do not eat shellfish from this waterbody. 

Incident Description: Samples taken on 8/23/21 indicate the toxin Microcystin / Nodularin level dropped to 3.34 ug/L which is at the caution advisory level. Due to previous results caution is being exercised and the advisory level is moving to Warning until we get more results. 8/12/21: The toxin Microcystin / Nodularin is at 69.08 ug/L far above the 20 ug/L Danger trigger level. Danger level advised. Regional board staff visited Crowley on 8/4/21 and visual indicators of a bloom are present. Samples were taken and results are pending. Caution is advised.

On 6/15/2021 Regional Water Quality Control Board sampled a location near the marina. The lab performed microscopic identification on the sample and found a low amount of Dolichospermum sp. qPCR did not detect amounts of the toxins Anatoxin-a, Cylindrospermopsin, Microcystins, and Saxitoxin. On 5/26/2021 Regional Water Quality Control Board sampled locations near the marina. Lab analysis showed no cyanobacteria present, no cyanotoxins analyzed.

Bridgeport Reservoir Danger

Current Advisory: Danger
Advisory Recommendations: STAY OUT OF THE WATER. Do not touch scum in the water or shore. Do NOT let pets go in the water, drink the water, or eat scum on the shore. Do not eat shellfish from this waterbody. 

Incident Description: On 8/26/21 Walker River Irrigation District sampled, and lab results indicate toxin levels well above the danger trigger level at 2,487.4 ug/L. Danger posting advised. 7/1/21- Water Board Staff recommended posting a caution advisory due to site indicators of a harmful algal bloom. Walker River Irrigation District will be keeping an eye on this location, and follow up testing will occur if the bloom worsens.

Toxic Algal blooms are common but can be very dangerous. Last month these blooms are believed to be responsible for a young families deaths near Yosemite.

How can I protect myself, my family, and my pets from freshwater HAB-related illness?

Learn more about HABs and related illness
CA HABs Portal:

stream bed

Who is tracking HAB-related illnesses in California?

The Interagency HAB-related Illness Workgroup has investigated and tracked potential HAB-related illnesses in humans and animals throughout California. The workgroup includes staff from the Office of Environmental Health Hazard Assessment (OEHAA), the State Water Resources Control Board, the California Department of Public Health (CDPH), and the California Department of Fish and Wildlife. All potential illness reports submitted to the workgroup undergo an evaluation of the available environmental and health-related information, and those considered HAB-related are included in final summaries (as noted below). The information presented on this web page can be downloaded as a factsheet.

Marine HAB-related illnesses in California are also investigated and tracked by this workgroup. For more information on marine HABs and how to report a potentially related human or animal illness, see OEHHA’s webpage on Marine HAB-related illnesses.

How many freshwater HAB-related illnesses have been reported for California?

From 2018 to 2020, CDPH reported 71 freshwater HAB-related human and animal illnesses for California to the Centers for Disease Control and Prevention (CDC) One Health Harmful Algal Bloom System (OHHABS). A summary of HAB-related illness by year is provided in the figure below.

Figure 1. Freshwater illnesses reported as HAB-related to OHHABS from 2018 – 2020. Number represents individuals (except when submitted as group, such as fish).

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