08-27-2005, 06:07 AM
Water is a valuable, necessary, and sometimes fun resource. People use it every day for drinking, cleaning, bathing, swimming, fishing, and any number of other activities, especially in western Oakland County where lakes and streams are abundant. As the county continues its gradual urban expansion and the population continues moving outward — mainly northwest — away from Detroit, the lakes area's water resources will continue to be affected. Likewise, the greater the growth, the greater the need for clean water.
With that in mind, Oakland County and the United States Geological Survey (USGS) began in 2001 a cooperative project to study and understand the county's water resources — its groundwater and its surface water — and the impact of urban sprawl on those resources. That study's report, now available to the public, indicates groundwater in the lakes area is among the county's most susceptible to contamination; and chloride and bacteria levels found in area lakes and streams has increased significantly since the late 1960s.
The study was conducted to serve as an update to a previous water resources assessment completed in 1972, which was based on information collected in the late 1960s.
Oakland County Human Services Director Dr. Thomas Gordon explained the importance of updating the 1972 study.
"Things have changed considerably since the late 1960s and very early 1970s, not only in terms of population, but in terms of sophistication, the number of septic tanks we have, and the vulnerability of our (groundwater) aquifers," he said. "We felt it was important to update it to give us a better idea of what the issues appear to be at the present time, and the types of concerns we should have (about) the county and our drinking water.
"It was also important in the aftermath of all the concerns regarding arsenic and other contaminants that were in some wells at very low levels in various areas of the county."
Until the 1960s, most of Oakland County used groundwater for its drinking water. According to the new water study report, as the population expanded into the northern and western portions of the county, the number of people relying on groundwater for their domestic water supply increased.
Although some new water lines have been added to tie into the Detroit supply system in recent years, most of the northern two tiers of Oakland's townships — as well as Highland Township, much of White Lake Township, portions of Commerce Township and Milford Township — still rely on groundwater for their water supply.
Public groundwater systems delivered approximately 22.87 million gallons of water per day (Mgal/d) to 169,000 county residents in 2000, and an additional 240,000 properties used private domestic-supply wells.
According to the new report, Oakland County's population has increased approximately 100,000 residents per decade since 1900, but the rate of increase paused briefly in the early 1980s. Since that point, however, the county has grown about 10,000 residents per year.
Between 1972 and 2000, the county's population jumped almost 50 percent, from 850,000 to 1.2 million, and its water usage increased 68 percent, from 100 Mgal/d to 168 Mgal/d.
The county is expected to grow by about 200,000 more people in the next 20 years, mostly in and near the lakes area — in the northern and western portions of the county — according to the report, and increase its total water usage by 20 Mgal/d.
"For another 200,000 residents they project the demand for drinkable water could go up 50 percent. Quite frankly, according to the USGS study, we do not have sufficient groundwater to take care of both the human needs and the environmental needs in the county," Gordon said. "There's either going to have to be some strategies to bring additional water to the county — either through new intake lines out in Lake St. Clair or the Great Lakes — or the other thing we can do is reduce the contamination that occurs."
The cost of the joint study was a little more than $600,000. In March 2001, the Oakland County Board of Commissioners agreed to pay $395,000 of the costs. USGS Geographer Steve Aichele said the federal agency picked up the remaining tab.
The entire USGS report, presented with numerous supplementary reports, can be found at on line at http://mi.water.usgs.gov/splan2/sp9G400.
<*C><*C>
<*L> In studying the county's groundwater resources, the USGS wanted to find out how susceptible to contamination aquifers may be.
USGS Geographer Ed Bissell, who with Aichele surveyed the county's surficial geology as part of the overall study, provided a supplementary report on the county's land permeability.
"What we were looking at was the potential ... to contaminate groundwater," he said. "We were looking at effective horizontal hydraulic activity to see where there are areas where the top layers of the soil have higher permeabilities.
"Basically we were looking at wells that were relatively shallow in relation to the land surface, and at the soil texture in the immediate vicinity.
"We tried to identify places where you're likely to find a confining layer, or clay layer, within 50 feet of the land surface," Aichele said. "Those sometimes provide protection from surface contamination."
Aichele said many of the groundwater aquifers in Highland, White Lake, Waterford, Milford, and Commerce are among the most susceptible to contamination in all of Oakland County.
A map in Bissell's supplementary report showed that the surficial geology throughout the lakes area consists primarily of end moraine (till); ground moraine (till); and outwash plain and glacial channel (sand and gravel).
Other sprinkles of land in the area are of different types of sand and gravel.
"Oakland County is heavily glaciated," Bissell said. "Most of the surficial materials are not very consistent; they're heterogeneous. Some are coarse and some are fine. The finer surficial materials will resist the flow of water."
He said it's up to county officials to determine which particular spots with groundwater wells are susceptible to contamination and where a confining layer does not exist, to provide some type of protection against contamination.
According to Bissell's supplementary report, a confining layer is typically composed of a poorly permeable clay that can provide protection for groundwater supplies.
The county's Gordon, who noted that the natural ability of the county's groundwater to recharge is diminished because of runoff from streets, highways, parking lots and other impervious surfaces, said one thing that can be done to protect groundwater sources is begin inspecting the county's septic tanks.
"We have roughly 84,000 on-site septic systems in this county," he said. "When you have that, it's like having 84,000 (departments of public works). Are these on-site wells and septic systems properly maintained and monitored by the homeowners? No, they're not."
According to Gordon, his department is still reviewing the cost of performing countywide septic tank inspections before taking an inspection ordinance proposal to the Oakland County Board of Commissioners, which would have to sign off on the plan.
"With the concern about the financial state of Michigan and how it affects all of the local communities, people are very concerned about the financial impact (septic inspections) will have on us at the local level," he said. "Consequently, they want to approach any new initiatives of this nature with due deliberation and consideration."
Much of the groundwater work presented in the new study report was material that had already been reported in previous studies, and was either verified through the new study or reflects updated regulations and standards.
"The results of what we did pretty much verified the surficial geology maps that were already created," Bissell said. "There was one that was created for the whole state in the early '80s and there was an update to that which was created a few years ago. We used the well logs to try to identify areas where there's lower or higher hydraulic activities. They matched up pretty well with the maps we'd been using."
As far as noting any particular contaminants found in the county's groundwater resources, sampling for traces of arsenic, nitrate, and chloride in groundwater was conducted during another study that took place between 1998 through 2000.
Aichele of the USGS said the old groundwater study, complete with detailed maps of each individual community in the county, was still presented along with the new study to serve as background, but was tweaked a little to reflect a change in arsenic standards.
"The EPA changed the arsenic standard for drinking water two to three years ago, and we did go through and update the maps and county fact sheets to incorporate the new standards," he said. "Almost all of the text is the same, though. Any of the places it said 50 micrograms per liter, we made it 10 micrograms per liter."
The old acceptable, maximum safe level of arsenic in drinking water was 50 micrograms per liter, which Aichele said had been the case since the government began regulating arsenic in drinking water.
"The (maximum) allowable level was changed in 2002 to go from 50 to 10 micrograms per liter," he said. "As a result, many more survey sections in Oakland County had at least one well that was over the new threshold. We altered the maps to show that. We just changed the way we colored the map. It's the same data."
Groundwater tests for the study were not conducted in every community by the USGS, although results were listed for each community in the county.
Aichele said the USGS, which runs its own water lab, compared its new results to older results from state testing.
"What we did was resample a lot of the wells the (state Department of Environmental Quality) had data for, for comparison purposes, more or less to test the results from the DEQ lab," he said. "Basically the DEQ lab performed as well as the USGS lab, so we generated the (new) maps with the DEQ data.
"That's how without collecting a USGS sample in Milford, for example, we were able to present data for Milford," he added. "Testing was relatively time consuming and somewhat expensive. We were typically doing four or five wells a day while we were sampling, so there wasn't time or money to do thousands of wells that way."
<*C><*C>
<*L> County groundwater contamination has the potential to carry over into the county's lakes, rivers, and other surface waters, since surface and groundwater are linked.
Oakland County contains the headwaters of five major river systems and a small part of a sixth. Three of those rivers — the Huron, Clinton, and Rouge — run through the lakes area. Western Oakland County is home to a good portion of the county's lakes, which exceed 1,000.
According to the new report, water circulates from the air down into the ground, up from there into the surface water, and then up into the air again.
Some contaminants don't carry harmful effects to the surface water, such as arsenic, which Aichele said stops being dangerous once exposed to oxygen when in surface waters.
However, other concerns for the surface waters do exist, such as various results of urban sprawl.
"One of the things I think we were surprised by was the chloride concentrations in the rivers and the lakes," Aichele said. "Nearly all of the river sites at least doubled their chloride concentration between the late 60s and the early 2000s."
Both Aichele and Gordon said the elevated chloride concentrations are a result of, in great part, the use of road salt.
At a Kent Lake (Milford Township) testing site, chloride had increased from 26 milligrams per liter (mg/L) in 1967 to 117 mg/L in 2003. At Wolverine Lake, the concentration increased from 62 mg/L in 1967 to 263 in 2003. At Union Lake, the number rose from 28 mg/L in 1967 to 118 mg/L in 2003. And at Lower Pettibone Lake in Highland Township, which had the lowest levels, the increase was from 15 mg/L in 1967 to 96 mg/L in 2003.
Gordon said he's concerned about the increased chloride concentrations, but said they aren't a health risk.
"That could potentially have an impact on the environmental aspect," Gordon said. "Does it have a big impact on the public health? Not really."
"I don't think the scientific community knows the effect of higher levels of chloride on most fish species or aquatic vegetation," Aichele said. "To my knowledge, the research just hasn't been done, except on a very few specific species."
Dexter-based consulting limnologist Wallace Fusilier said proliferation of a modern and common household convenience could be another reason that chloride concentrations are up in county lakes and rivers.
"Certainly chlorides could increase because more people are using water softeners," he said. "Sewage treatment plants are telling people not to dump the effluent from the water softener into the sewer, especially in groundwater discharge systems, because you're increasing the salt concentration in the groundwater. They're requiring them to dump their water softener brine that they use to regenerate the water softener back into the lakes."
Fusilier said that a water body's salt content — including chloride — correlates to its conductance, which is what he said he tests for when looking for salt content in surface water. Conductance of specific surface water resources was also part of the new county water study.
"Pure, distilled water doesn't conduct electricity very well. What makes water conduct electricity is the stuff that's dissolved in it," Aichele said. "So, you can use the ability of the water to conduct electricity as an indicator of the amount of material dissolved in the water. So as the specific conductance increases, the amount of material dissolved in the water increases. It's a very sound, stable relationship. And it's an easy measurement to make (with the technology available)."
At Kent Lake, specific conductance was up from 457 microsiemens per centimeter in 1967 to 730 in 2003. During the same time span the specific conductance also increased from 485 to 1,080 in Wolverine Lake, 397 to 676 in Union Lake, and 370 to 695 in Lower Pettibone Lake.
Two of the other major contaminants monitored in the lakes were down across the county as a whole, but their concentrations in lakes area surface water increased.
Lakes area sulfate test results, many of which Aichele said had become contaminated or weren't conclusive, couldn't be used. At Wolverine Lake the sulfate concentration increased from 22 mg/L to 32.2 mg/L between 1967 and 2003. The 2003 results were inconclusive for the other highlighted lakes in the report. The 1967 concentrations, however, were as follows: 39 mg/L at Kent Lake, 24 mg/L at Union Lake, and 22 mg/L at Lower Pettibone Lake.
The opposite was true of nitrate — some of the 1967 results weren't available for the selected lakes, while the 2003 results were included in the new study report. At Kent Lake, nitrates increased from 0.045 mg/L in 1967 to 0.144 mg/L in 2003. Union Lake saw concentrations increase from 0.0 mg/L to 0.084 mg/L in that time period. Wolverine Lake's nitrate total in 2003 was less than 0.022 mg/L and Lower Pettibone Lake's total was 0.353 mg/L.
None of those totals would be harmful to people, aquatic life, or aquatic vegetation, according to Fusilier.
"The standard for nitrates that causes health problems for humans is 10 milligrams per liter," he said, noting also that it won't affect fish. "You'll get more plants in the water with high nitrates if there's enough phosphorous there. I've never seen a concentration of nitrates high enough to exceed 10 milligrams per liter."
One of the other test results that the county's Gordon said is of concern is the concentration of antibiotic-resistant bacteria and E. coli in Oakland's surface waters.
"I'd like to do more studies in that area," he said, adding that notable E. coli concentrations aren't limited to Oakland County. "Quite frankly, we don't know enough about that yet to know if it's a big concern, as long as it's not in the drinking water. When this is in the surface water, we get concerned because our surface water and our drinking water pull water from the same aquifers."
Aichele said the E. coli concentrations weren't high enough to cause harm to anyone, either through ingestion or incidental contact.
"The DEQ contact standard for bathing water, I believe, is 300 Colony Forming Units (CFU) per 100 milliliters (ml), so many of these sites wouldn't have passed," he said. "I was out there a lot, and I didn't see a lot of people swimming at these sites, and really couldn't imagine it."
Two of six samples from one Clinton River testing site exceeded 300 CFU/ml, four of 10 samples at another Clinton River site exceeded the standard, and five of nine did at another site on the Clinton River.
At one Huron River site, none of the seven samples exceeded the 300 CFU/ml mark, and at another Huron River site, two of eight did.
Seven of nine samples at one Rouge River site exceeded 300 CFU/ml and another there had six samples of nine exceed the mark.
"If you have a regular source of E. coli being discharged in a lake — say a sewage treatment plant that's not chlorinating heavily enough — and you consistently get high E. coli, then you can say there's a problem," Fusilier said. "But, if you get occasional E. coli, that really doesn't indicate a problem."
"Again, is it at levels that causes reason for health concern?" Gordon noted of the antibiotic-resistant material found. "No, at the present time it's not, but that doesn't mean we shouldn't try to find out more about it to find out if it's something of an insidious contaminant that could cause problems in the future."
Gordon said that prevention is the best solution.
[black][size 4]"A good public health approach to anything is to try to prevent problems to the extent you can before they occur rather than to try resolving a problem once it's occurred," he said. "It's much more expensive to try to resolve it afterwards than it is to try to prevent it to begin with through good, thoughtful planning."[/size][/black]
[signature]
With that in mind, Oakland County and the United States Geological Survey (USGS) began in 2001 a cooperative project to study and understand the county's water resources — its groundwater and its surface water — and the impact of urban sprawl on those resources. That study's report, now available to the public, indicates groundwater in the lakes area is among the county's most susceptible to contamination; and chloride and bacteria levels found in area lakes and streams has increased significantly since the late 1960s.
The study was conducted to serve as an update to a previous water resources assessment completed in 1972, which was based on information collected in the late 1960s.
Oakland County Human Services Director Dr. Thomas Gordon explained the importance of updating the 1972 study.
"Things have changed considerably since the late 1960s and very early 1970s, not only in terms of population, but in terms of sophistication, the number of septic tanks we have, and the vulnerability of our (groundwater) aquifers," he said. "We felt it was important to update it to give us a better idea of what the issues appear to be at the present time, and the types of concerns we should have (about) the county and our drinking water.
"It was also important in the aftermath of all the concerns regarding arsenic and other contaminants that were in some wells at very low levels in various areas of the county."
Until the 1960s, most of Oakland County used groundwater for its drinking water. According to the new water study report, as the population expanded into the northern and western portions of the county, the number of people relying on groundwater for their domestic water supply increased.
Although some new water lines have been added to tie into the Detroit supply system in recent years, most of the northern two tiers of Oakland's townships — as well as Highland Township, much of White Lake Township, portions of Commerce Township and Milford Township — still rely on groundwater for their water supply.
Public groundwater systems delivered approximately 22.87 million gallons of water per day (Mgal/d) to 169,000 county residents in 2000, and an additional 240,000 properties used private domestic-supply wells.
According to the new report, Oakland County's population has increased approximately 100,000 residents per decade since 1900, but the rate of increase paused briefly in the early 1980s. Since that point, however, the county has grown about 10,000 residents per year.
Between 1972 and 2000, the county's population jumped almost 50 percent, from 850,000 to 1.2 million, and its water usage increased 68 percent, from 100 Mgal/d to 168 Mgal/d.
The county is expected to grow by about 200,000 more people in the next 20 years, mostly in and near the lakes area — in the northern and western portions of the county — according to the report, and increase its total water usage by 20 Mgal/d.
"For another 200,000 residents they project the demand for drinkable water could go up 50 percent. Quite frankly, according to the USGS study, we do not have sufficient groundwater to take care of both the human needs and the environmental needs in the county," Gordon said. "There's either going to have to be some strategies to bring additional water to the county — either through new intake lines out in Lake St. Clair or the Great Lakes — or the other thing we can do is reduce the contamination that occurs."
The cost of the joint study was a little more than $600,000. In March 2001, the Oakland County Board of Commissioners agreed to pay $395,000 of the costs. USGS Geographer Steve Aichele said the federal agency picked up the remaining tab.
The entire USGS report, presented with numerous supplementary reports, can be found at on line at http://mi.water.usgs.gov/splan2/sp9G400.
<*C><*C>
<*L> In studying the county's groundwater resources, the USGS wanted to find out how susceptible to contamination aquifers may be.
USGS Geographer Ed Bissell, who with Aichele surveyed the county's surficial geology as part of the overall study, provided a supplementary report on the county's land permeability.
"What we were looking at was the potential ... to contaminate groundwater," he said. "We were looking at effective horizontal hydraulic activity to see where there are areas where the top layers of the soil have higher permeabilities.
"Basically we were looking at wells that were relatively shallow in relation to the land surface, and at the soil texture in the immediate vicinity.
"We tried to identify places where you're likely to find a confining layer, or clay layer, within 50 feet of the land surface," Aichele said. "Those sometimes provide protection from surface contamination."
Aichele said many of the groundwater aquifers in Highland, White Lake, Waterford, Milford, and Commerce are among the most susceptible to contamination in all of Oakland County.
A map in Bissell's supplementary report showed that the surficial geology throughout the lakes area consists primarily of end moraine (till); ground moraine (till); and outwash plain and glacial channel (sand and gravel).
Other sprinkles of land in the area are of different types of sand and gravel.
"Oakland County is heavily glaciated," Bissell said. "Most of the surficial materials are not very consistent; they're heterogeneous. Some are coarse and some are fine. The finer surficial materials will resist the flow of water."
He said it's up to county officials to determine which particular spots with groundwater wells are susceptible to contamination and where a confining layer does not exist, to provide some type of protection against contamination.
According to Bissell's supplementary report, a confining layer is typically composed of a poorly permeable clay that can provide protection for groundwater supplies.
The county's Gordon, who noted that the natural ability of the county's groundwater to recharge is diminished because of runoff from streets, highways, parking lots and other impervious surfaces, said one thing that can be done to protect groundwater sources is begin inspecting the county's septic tanks.
"We have roughly 84,000 on-site septic systems in this county," he said. "When you have that, it's like having 84,000 (departments of public works). Are these on-site wells and septic systems properly maintained and monitored by the homeowners? No, they're not."
According to Gordon, his department is still reviewing the cost of performing countywide septic tank inspections before taking an inspection ordinance proposal to the Oakland County Board of Commissioners, which would have to sign off on the plan.
"With the concern about the financial state of Michigan and how it affects all of the local communities, people are very concerned about the financial impact (septic inspections) will have on us at the local level," he said. "Consequently, they want to approach any new initiatives of this nature with due deliberation and consideration."
Much of the groundwater work presented in the new study report was material that had already been reported in previous studies, and was either verified through the new study or reflects updated regulations and standards.
"The results of what we did pretty much verified the surficial geology maps that were already created," Bissell said. "There was one that was created for the whole state in the early '80s and there was an update to that which was created a few years ago. We used the well logs to try to identify areas where there's lower or higher hydraulic activities. They matched up pretty well with the maps we'd been using."
As far as noting any particular contaminants found in the county's groundwater resources, sampling for traces of arsenic, nitrate, and chloride in groundwater was conducted during another study that took place between 1998 through 2000.
Aichele of the USGS said the old groundwater study, complete with detailed maps of each individual community in the county, was still presented along with the new study to serve as background, but was tweaked a little to reflect a change in arsenic standards.
"The EPA changed the arsenic standard for drinking water two to three years ago, and we did go through and update the maps and county fact sheets to incorporate the new standards," he said. "Almost all of the text is the same, though. Any of the places it said 50 micrograms per liter, we made it 10 micrograms per liter."
The old acceptable, maximum safe level of arsenic in drinking water was 50 micrograms per liter, which Aichele said had been the case since the government began regulating arsenic in drinking water.
"The (maximum) allowable level was changed in 2002 to go from 50 to 10 micrograms per liter," he said. "As a result, many more survey sections in Oakland County had at least one well that was over the new threshold. We altered the maps to show that. We just changed the way we colored the map. It's the same data."
Groundwater tests for the study were not conducted in every community by the USGS, although results were listed for each community in the county.
Aichele said the USGS, which runs its own water lab, compared its new results to older results from state testing.
"What we did was resample a lot of the wells the (state Department of Environmental Quality) had data for, for comparison purposes, more or less to test the results from the DEQ lab," he said. "Basically the DEQ lab performed as well as the USGS lab, so we generated the (new) maps with the DEQ data.
"That's how without collecting a USGS sample in Milford, for example, we were able to present data for Milford," he added. "Testing was relatively time consuming and somewhat expensive. We were typically doing four or five wells a day while we were sampling, so there wasn't time or money to do thousands of wells that way."
<*C><*C>
<*L> County groundwater contamination has the potential to carry over into the county's lakes, rivers, and other surface waters, since surface and groundwater are linked.
Oakland County contains the headwaters of five major river systems and a small part of a sixth. Three of those rivers — the Huron, Clinton, and Rouge — run through the lakes area. Western Oakland County is home to a good portion of the county's lakes, which exceed 1,000.
According to the new report, water circulates from the air down into the ground, up from there into the surface water, and then up into the air again.
Some contaminants don't carry harmful effects to the surface water, such as arsenic, which Aichele said stops being dangerous once exposed to oxygen when in surface waters.
However, other concerns for the surface waters do exist, such as various results of urban sprawl.
"One of the things I think we were surprised by was the chloride concentrations in the rivers and the lakes," Aichele said. "Nearly all of the river sites at least doubled their chloride concentration between the late 60s and the early 2000s."
Both Aichele and Gordon said the elevated chloride concentrations are a result of, in great part, the use of road salt.
At a Kent Lake (Milford Township) testing site, chloride had increased from 26 milligrams per liter (mg/L) in 1967 to 117 mg/L in 2003. At Wolverine Lake, the concentration increased from 62 mg/L in 1967 to 263 in 2003. At Union Lake, the number rose from 28 mg/L in 1967 to 118 mg/L in 2003. And at Lower Pettibone Lake in Highland Township, which had the lowest levels, the increase was from 15 mg/L in 1967 to 96 mg/L in 2003.
Gordon said he's concerned about the increased chloride concentrations, but said they aren't a health risk.
"That could potentially have an impact on the environmental aspect," Gordon said. "Does it have a big impact on the public health? Not really."
"I don't think the scientific community knows the effect of higher levels of chloride on most fish species or aquatic vegetation," Aichele said. "To my knowledge, the research just hasn't been done, except on a very few specific species."
Dexter-based consulting limnologist Wallace Fusilier said proliferation of a modern and common household convenience could be another reason that chloride concentrations are up in county lakes and rivers.
"Certainly chlorides could increase because more people are using water softeners," he said. "Sewage treatment plants are telling people not to dump the effluent from the water softener into the sewer, especially in groundwater discharge systems, because you're increasing the salt concentration in the groundwater. They're requiring them to dump their water softener brine that they use to regenerate the water softener back into the lakes."
Fusilier said that a water body's salt content — including chloride — correlates to its conductance, which is what he said he tests for when looking for salt content in surface water. Conductance of specific surface water resources was also part of the new county water study.
"Pure, distilled water doesn't conduct electricity very well. What makes water conduct electricity is the stuff that's dissolved in it," Aichele said. "So, you can use the ability of the water to conduct electricity as an indicator of the amount of material dissolved in the water. So as the specific conductance increases, the amount of material dissolved in the water increases. It's a very sound, stable relationship. And it's an easy measurement to make (with the technology available)."
At Kent Lake, specific conductance was up from 457 microsiemens per centimeter in 1967 to 730 in 2003. During the same time span the specific conductance also increased from 485 to 1,080 in Wolverine Lake, 397 to 676 in Union Lake, and 370 to 695 in Lower Pettibone Lake.
Two of the other major contaminants monitored in the lakes were down across the county as a whole, but their concentrations in lakes area surface water increased.
Lakes area sulfate test results, many of which Aichele said had become contaminated or weren't conclusive, couldn't be used. At Wolverine Lake the sulfate concentration increased from 22 mg/L to 32.2 mg/L between 1967 and 2003. The 2003 results were inconclusive for the other highlighted lakes in the report. The 1967 concentrations, however, were as follows: 39 mg/L at Kent Lake, 24 mg/L at Union Lake, and 22 mg/L at Lower Pettibone Lake.
The opposite was true of nitrate — some of the 1967 results weren't available for the selected lakes, while the 2003 results were included in the new study report. At Kent Lake, nitrates increased from 0.045 mg/L in 1967 to 0.144 mg/L in 2003. Union Lake saw concentrations increase from 0.0 mg/L to 0.084 mg/L in that time period. Wolverine Lake's nitrate total in 2003 was less than 0.022 mg/L and Lower Pettibone Lake's total was 0.353 mg/L.
None of those totals would be harmful to people, aquatic life, or aquatic vegetation, according to Fusilier.
"The standard for nitrates that causes health problems for humans is 10 milligrams per liter," he said, noting also that it won't affect fish. "You'll get more plants in the water with high nitrates if there's enough phosphorous there. I've never seen a concentration of nitrates high enough to exceed 10 milligrams per liter."
One of the other test results that the county's Gordon said is of concern is the concentration of antibiotic-resistant bacteria and E. coli in Oakland's surface waters.
"I'd like to do more studies in that area," he said, adding that notable E. coli concentrations aren't limited to Oakland County. "Quite frankly, we don't know enough about that yet to know if it's a big concern, as long as it's not in the drinking water. When this is in the surface water, we get concerned because our surface water and our drinking water pull water from the same aquifers."
Aichele said the E. coli concentrations weren't high enough to cause harm to anyone, either through ingestion or incidental contact.
"The DEQ contact standard for bathing water, I believe, is 300 Colony Forming Units (CFU) per 100 milliliters (ml), so many of these sites wouldn't have passed," he said. "I was out there a lot, and I didn't see a lot of people swimming at these sites, and really couldn't imagine it."
Two of six samples from one Clinton River testing site exceeded 300 CFU/ml, four of 10 samples at another Clinton River site exceeded the standard, and five of nine did at another site on the Clinton River.
At one Huron River site, none of the seven samples exceeded the 300 CFU/ml mark, and at another Huron River site, two of eight did.
Seven of nine samples at one Rouge River site exceeded 300 CFU/ml and another there had six samples of nine exceed the mark.
"If you have a regular source of E. coli being discharged in a lake — say a sewage treatment plant that's not chlorinating heavily enough — and you consistently get high E. coli, then you can say there's a problem," Fusilier said. "But, if you get occasional E. coli, that really doesn't indicate a problem."
"Again, is it at levels that causes reason for health concern?" Gordon noted of the antibiotic-resistant material found. "No, at the present time it's not, but that doesn't mean we shouldn't try to find out more about it to find out if it's something of an insidious contaminant that could cause problems in the future."
Gordon said that prevention is the best solution.
[black][size 4]"A good public health approach to anything is to try to prevent problems to the extent you can before they occur rather than to try resolving a problem once it's occurred," he said. "It's much more expensive to try to resolve it afterwards than it is to try to prevent it to begin with through good, thoughtful planning."[/size][/black]
[signature]