Update for February 16, 2010

As part of the Upper Oso Reservoir lake management strategy, the Board of Directors of the Santa Margarita Water District recently approved the installation of Oxygenation Equipment at the reservoir. The new equipment will help increase dissolved oxygen in the water to avoid odors due to seasonal weather changes and lake turnovers. To learn more, view the recent press release issued by the District.

November 24, 2009

All indicators show that the Upper Oso Reservoir remains healthy. SMWD continues to review data provided from the lake’s recent turnover and develop a long-term lake management strategy to avoid recurrence.

November 19, 2009

A public presentation on the Upper Oso Reservoir was made at the Board of Directors meeting held yesterday evening. The presentation was given by SMWD General Manager John Schatz and Andrew Komor (MS,PE) from Pacific Advanced Civil Engineering (PACE), a civil engineering firm specializing in advanced water resources and consultant to SMWD on the Upper Oso Reservoir. Four representatives from the South Coast Air Quality Management District (AQMD) were in attendance to speak on behalf of air testing conducted near the reservoir and its findings in its report released on November 18. SMWD and its team of experts answered questions and addressed concerns of the four members of the public that were in attendance.

November 18, 2009

Today, the South Coast Air Quality Management District (AQMD) released its "Information Advisory & Status Update" for the odors at the Santa Margarita Water District's Upper Oso Reservoir. Over the last few weeks, SMWD has worked closely with AQMD and the County of Orange Health Care Agency to ensure the public's safety. AQMD's summary of the events and their findings can be found in the report.

November 17, 2009

Improvements in all markers continue on the Upper Oso Reservoir today. Water tests from this morning show an increase in oxygen reduction potential (ORP) levels, which means sulfide levels continue to drop and oxygen is returning to the lake.

For a comprehensive, two-week summary of the activities at the Upper Oso Reservoir, please click here.

The lake continues to improve. The photos above show the lake on October 31(left) and November 16 (right).

Today's water tests showed dissolved oxygen levels at 3.55 mg/l at 15 feet, and at 3.88 mg/l at 1 foot. The District is pleased with these increases and hopes to see increases to 4 or 4.5 mg/l which would indicate average conditions. In addition, there were no detectable soluble sulfides found in the water when tested to a 40 foot depth.

November 13, 2009

Early this morning the District distributed 16,000 pounds of oxygenating compound into the water near the dam at the deepest part of the reservoir, which is where it was needed (see picture above). We saw immediate improvement in water quality indicators. Quality measures throughout the reservoir (dissolved oxygen levels and sulfide) continually improve. Ozone and aeration continue. Reservoir clarity is markedly better, which is another indication the restoration measures are effective. While reservoir indicators are on the upswing, the variable has been changes in the weather (particularly cooler evenings and wind patterns) that drive odor migration.

November 12, 2009

SMWD continues to aerate the lake and agitate the surface water with boats. Due to the water moving and mixing, sulfides in the lake's water come to the surface and cause the odor which nearby residents continue to smell. This biological process must take place for the lake to return to a healthy state.

The District will be adding sodium percarbonate into the lake to help eliminate the sulfides in the water and further accelerate the restoration of normal oxygen levels.

The above photo shows the activities continuing at Oso Reservoir. We appreciate the community's patience as we work diligently to return the lake back to normal. To view a letter regarding efforts to date, please click here.

November 10, 2009

Today, the District installed two new aeration pumps to operate in the lake. Some residents who live along the ridgeline in the Painted Trails community may hear the new generator which is providing electricity to operate the two new aeration pumps. Please contact SMWD directly at 459-6420 if this poses a problem with noise levels. The lake’s color and clarity continue to look good. Today’s water tests show an increase in oxygen reduction potential (ORP) levels, which means sulfide levels are dropping and oxygen is returning to the lake. ORP testing is done to provide a more precise measure of oxygen concentration levels in the water. The photo above shows the plume of oxygenated water emanating from the diffusers in the deepest part of the reservoir.

November 9, 2009

The cooler, drier weather at night and in the early morning has caused the odor to migrate into the nearby neighborhoods. This is the reason some people may have smelled stronger odors Sunday and this morning. Last week's nighttime and morning fog helped keep the odor near the lake, not into the neighborhoods.

Though nearby residents smelled stronger odors the past 24 hours, the health indicators of the lake are still improving. Today, the lake's color looked good, and clarity has greatly increased over the weekend. All the aeration equipment continues to operate and the ozone production was increased to its maximum level. The District is coordinating to install two more aeration pumps on Tuesday to further help get the lake back to normal levels.

November 8, 2009

The District is noting more signs of recovery in the Upper Oso Reservoir including the lake's depth clarity increasing from 1.5 feet to 2.5 feet. Ozone has been bubbled into the reservoir since Saturday and the amount being injected was increased today. The District continues to operate all the mechanical aeration devices including the Solar Bees, aeration pumps, fountain spray and bubblers, as well as operate boats to stir the surface waters.

We appreciate the community's patience as we work to help the reservoir recover to its full health.

November 7, 2009

Aeration activities continue throughout the weekend - many around the clock - as well as water and air testing. In addition, the ozone equipment is operational. The District continues to see improvements in the lake's health. The photo above shows the two aeration pumps which were installed into the lake on Friday.

November 6, 2009

A lot of activity is happening on the lake. The two air diffusers installed Thursday continue to operate at the north end of the lake, where there was previously limited mechanical aeration. Since its delivery this morning, the District is now installing the ozone generation equipment and it’s still expected to be operating by late afternoon, pumping 50 pounds of ozone (oxygen-rich air) into our compressor line in the lake. SMWD is also installing today two aeration pumps borrowed from IRWD. These pumps pull water from a 4-foot depth and spray out over the top – similar to a fountain – and help aerate the water.

If you are interested in learning more about the Upper Oso Reservoir, click here to view a presentation by SMWD.

November 5, 2009

A clear band of water is now about 2 feet out from the shoreline instead of 1 foot yesterday (see photo). This is good news and an improvement from yesterday. The ozone equipment will be at the reservoir at 6:00 a.m. tomorrow, Friday, to start installation. The equipment is expected to be operational in the afternoon. SMWD is also building another diffuser panel from extra equipment we have from the treatment plant to add more air at the north end of the reservoir. The District is hoping to have that in place today.

A letter from SMWD General Manager John Schatz was mailed to residents in Rancho Santa Margarita and Mission Viejo who live nearby the reservoir. To view, please click here.

November 4, 2009

SMWD continues to aerate the lake to increase oxygen levels. The District is expected to install at the reservoir the ozone equipment by late Friday. This equipment generates ozone, a molecule consisting of three oxygen atoms instead of the two atoms found in the oxygen we breathe, which will help penetrate oxygen into the lake at a much faster rate than normal air.

Today's testing has shown the levels of oxygen along the shoreline to be increasing along with the "good" algae growth which indicates photosynthesis is occurring. While the affect on the odor may be minimal, it is a sign that the lake is beginning to recover.

November 3, 2009

The lake oxygen levels at the surface have increased slightly, while lower levels remain low. The dissolved oxygen levels are used as an indication of the health of the reservoir. Higher numbers indicate an increase in photosynthesis activity and a return of beneficial algae growth.

SMWD is continuing to monitor the water and air quality. The site was visited by South Coast Air Quality Management District personnel who note the odor was a nuisance but was not considered a health risk.

The activities to aerate the reservoir are continuing, please check back for daily updates.

November 2, 2009

To help return the lake’s oxygen levels to normal, SMWD has added equipment into the lake, including mechanical aeration (in addition to the existing solar-powered aeration equipment) as well as external pumps to spray the lake water to increase oxygen levels and stir up the lake’s surface for better oxygen transfer. In addition, fresh water is being added into the reservoir to help with the water quality. Further investigation is underway to aerate with ozone to increase the level of oxygen at an even faster pace. The District continues to sample the water regularly and monitor the health of the reservoir. SMWD has also performed extensive air monitoring around the lake and in the neighborhoods hardest hit with the odor and there are no detectable levels of hydrogen sulfides or other harmful gases.

October 29, 2009

The recent cold weather spell has affected the Upper Oso Reservoir. During the summer the lake splits into two layers of water. The top layer is warmer during the summer and maintains adequate levels of oxygen, but at the expense of the bottom of lake. The bottom of the lake has cooler water and stays isolated with low levels of oxygen. During autumn, the upper layer of water gets cold, and eventually sinks to the bottom, raising the bottom water. This year the recent cold spell came with strong winds that mixed the water suddenly creating conditions that caused an algae bloom which used up the oxygen which resulted in odors. The District has responded by adding additional equipment in the lake to help return the oxygen levels to normal. The situation does not pose any health risks and the reservoir should return to normal within the next several days.