Lake to Tap

PO Box 246, Ringwood, NJ  07456

July 9, 2002


Date/ Time 7/9/02, 1:00     |   Location – Lake Iosco Dam



Color, CUs


Turbidity, NTUs


Odor, 1-3

1 Grassy

pH, pH units


Conductance, uS/cm


Algae, cells / ml


% Taste and Odor


Dominant Organisms

Ankistrodesums, Ceratium

Total Phos, uG/L


Chlorophyll A, ug/L

< Detection Unit













Lake Iosco

Water Quality Report





'Lake to Tap' was one of the firms that Lake Iosco contacted requesting a proposal to perform a Nutrient Budget per the Heideman recommendations of August, 2001.  Lake to Tap is a professional lake management firm.  Although the Board decided against the high cost of the Nutrient Budget, Lake to Tap very kindly took the initiative to perform a fairly comprehensive test of the lake on July 9th, without charge to Lake Iosco.  The test was taken from the North dam.


The following summary presents an explanation of the issues and significance of each reading involved in the test.


The factors included in this test are the key metrics to judge the eutrophication of the lake, and the results are favorable.  The lake is healthy.  Recommendation is to continue to do testing twice/year and take samples from a few more locations as part of a preventative maintenance program.  The cost of each test would be around $1,000.


Lake to Tap did NOT feel that we have a problem with leaf litter.  They cited a study from Glenwild taken in fall that showed only very moderate phosphorous levels during peak fall season, and negligible the rest of the year.



Color:  20

Indication of irons & metals in the water.  20 is reasonable - not high.  There are no health hazards associated with color per drinking water act - standard for finished water is 15.  Should be pretty constant.


Turbidity, NTU's:  3.54

Great result - lower numbers are better.  Indication of cloudiness and particulates suspended in water.  Reservoir is usually around 20, Safe Drinking Water act does have standards (0.5) for finished water treatment plant because particulate may include algae bacteria.   Turbidity reading of between 10-40 would be common in lakes.


Odor, 1-3:  1 Grassy

Measured on threshold odor level, 3 is the worst (ex. heavy algae blooms).  Grassy is fine - good reading.  This is a subjective test depending on the tester’s nose.


pH, pH Units:  7.8

Most US lakes are between 6.8 and 7.2.  Reading of 7.8 indicates MODEST amounts of photosynthetic algae. Still low - during algae blooms the reading could easily be in the 9's.  Algae blooms take in CO2 and produce oxygen, increasing pH.  This reading does not seem to require treatment until 8.3 or so.  Lake to Tap guesses 28 - 35 parts alkalinity.  She characterized pH of 7.8 as “very modest . . . respectable.”


Conductance, uS/cm:  119

Measure of all of the minerals in the water.  Units are microsemens per centimeter.  Can be directly related to suspended solids.  119 is pretty low (favorable), but typical of lake and surface waters.  Reservoir is usually about 140 - 150.  Passaic Valley River is 180 - 300.  Ground wells usually 300 - 400.  Don't want it below 100 or over 500.


Algae, cells/ml:  56

Extremely low... actually surprising. BUT - the same time we were getting 56, the reservoir was getting counts of 250 to 400.   Even later blooms would not be bad in comparison, although later tests would be worthwhile.  Did not see any microscopic organisms.


% Taste and Odor:  25%

1/4 of the samples were organisms that produce taste and odor, but may be high given the very low algae count in the sample. Start having noticeable problems above 40% (smell, consumer complaints).  (She said that the scale ranges between 0 and 56.)


Dominant Organisms:  Ankistrodesmus, Ceratium

Typical of early season.  Ank. is Diatom - species that you normally see in cooler weather months.  Means water hadn't warmed up that much yet when sample was taken.  See diatoms in winter, then in summer see more chlorophycia (green) algaes.  Then by August, Labor Day phosphorous levels drop and see more blue-green algae (which cause algae blooms and smell).  As long as we have diatoms and greens, there are no algae-related problems.


Total Phosphorous, ug/l:  30

Reading of 30 is "not bad but not fantastic".  The max should be 20, or you will get algae blooms.  Most lakes will not be below 20, and consequently get modest algae blooms.  This reading was enough to allow algae blooms later in hotter weather.  We should continue to monitor phosphorous at least twice yearly - preferably more.  This test has margin of error of 7 points (actual reading could be between 23 - 37).  Lake to Tap would expect to find a variance of as much as twice that depending on time of year and where sampled (13 to 60).  Should take samples in late spring (early growing season - phosphates highest, algae lowest) and then again late summer.  Expect higher readings around houses. 


We were strongly advised to track the level of phosphorous and algae every year, and graph these results.  Somewhere down the line we will -probably have to do some treatment or restoration (such as Alum -private lakes in NJ have applied alum to the lake bottom over a period of years as an algae inhibitor.)  By tracking data over time will reduce analysis - and cost - when it comes time to treat.


To illustrate the importance of tracking nutrient levels, Lake to Tap cited the example of Culver Lake.  Their phosphorous got up to 80 ppb.  They lost fish, had algae, no oxygen, ecology was disrupted.  Put in aerators, which were expensive.  Also did biomanipulation - including stocking the lake with hybrid striped bass that would eat the smaller game fish that in turn eat phytoplankton - therefore enables phytoplankton to increase (good).  Also added Alum.  Reduced phosphorous count from 80 down to 17.  Should never have allowed it to get to 80, though… if they had a testing program in place they would most likely have identified the problem much earlier and required less drastic action.


NOTE:  Phosphorous is obviously a major consideration, and one that we could have some direct control over - septic management, disallowing fertilizer, etc.


Chlorophyll A, ug/l: (Below detection limit)

Detection limit is 3 micrograms per liter.  This reading goes along with our low microscopic reading (56).  Bloom would be around 40 micrograms per liter at reservoir, but algae count is around 1000 cells.  We should stay under 20 micrograms/liter.