Global Courant
When considering a nearby swimming hole this summer, aquatic scientists recommend that Los Angeles County residents check the latter first river report card before taking a dip.
While freshwater recreation sites across LA have seen improvements in recent years, scientists at the environmental nonprofit Heal the bay note that there is still much work to be done to limit the pollution of the waterways.
Last summer, nearly one-fifth of the 35 LA County sites analyzed posed a high risk to human health, according to the group’s fifth annual river report. About 65% tested in the “green” range – considered healthy for swimmers – and about 15% were in the moderate health risk category.
“While it is encouraging to see freshwater recreation areas have clean water most of the time, there is still a long way to go given that ocean beaches have good water quality 95% of the time,” said Luke Ginger, a water quality scientist. with Heal the Bay, a Los Angeles environmental organization focused on clean waterways.
The river report card was released Wednesday, along with the group’s beach report card, which highlights coastlines with the dirtiest and cleanest waters.
From Memorial Day through Labor Day 2022, Heal the Bay scientists tested waterways and used data from other monitoring programs and government agencies to assess water quality in some recreational areas, measuring the presence of contamination from fecal indicator bacteria.
“The lower Los Angeles River generally has much higher concentrations of bacteria compared to the upper reaches of the river,” Ginger said. He hopes more research can remedy this, but he said the reason likely lies in reduced habitat and green space as the river flows downstream through more urban areas.
Here are LA County’s 10 worst locations for water quality, considered the “freshwater fail.” The first three locations have finished worst after testing every week during the summer in the worst category for health.
The dirtiest freshwater areas in LA County
1. LA River at Riverfront Park
2. Compton Creek (shared first)
3. Tujunga Wash at Hansen Dam (tied for first)
4. LA River below the Rio Dondo Confluence
5. LA River at Willow Street
6. LA River at Hollydale Park
7. LA River below the Compton Creek Confluence
8. Bull Creek
9. Lake Balboa boat ramp
10. Las Virgenes Creek
Every location is part of the LA River Watershed except Number 10, which is in the Malibu Creek watershed, the report said.
“Most of these sites are in developed areas and receive large amounts of urban runoff,” Ginger said. “Six out of 10 freshwater disturbances are in the lower LA River, south of downtown LA”
The cleanest waterholes, considered on the “Honor Roll,” tied for first place eight times after testing every week last summer in the healthiest category, the report said. These are: San Gabriel River Upper Cattle Canyon; San Gabriel River East Fork at Graveyard Canyon; Hansen Dam lake; San Gabriel River Upper West Fork and Upper East Fork and Lower West Fork; Great Tijunga Creek at Vogel Flatts; and Delta flats.
The last two locations on the healthiest Top 10 list were Eaton Canyon and San Gabriel River Upper North Fork.
Six of the 10 honor roll sites are in the upper San Gabriel River in the Angeles National Forest, which also includes Big Tujunga Creek and Eaton Canyon. Hansen Dam Lake was the only place of honor that was not in the mountains.
“Our goal is to highlight water quality concerns, advocate for water quality improvements, and provide community members with the information they need to keep themselves safe and healthy when enjoying their local swimming pool the report said. Heal the Bay officials recommend that people avoid contact with water for at least three days after a heavy downpour.
“The biggest cause of poor water quality in our waterways is runoff,” said Tracy Quinn, president and CEO of Heal the Bay. While this river report didn’t take into account this winter’s excessive rainfall — it only covered the summer months — she said it’s important to account for these extremes in the future.
“Capturing rainwater on any scale can help us reduce the pollution that reaches our rivers, lakes and oceans,” Quinn said.
