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Observations - December 2016 ● The December testing was performed during a severe flood event that caused flooding in many parts of the San Geronimo Valley and throughout Marin County. ● Between November 2016 and February 2017, the Ross Valley Sanitary District spilled 122,000 gallons of sewage. Marin’s 27 other agencies spilled an additional 41,000 gallons of sewage in the same time period.

Observations - December 2016 Values less than .10 indicate low signal source - unlikely source Values between .10 and .19 indicate marginal signal source - possible source, further testing required (yellow) Values equal to or greater than .20 indicate strong signal source - likely source (red) Site Bird Dog Horse Human Pig Ruminant 1 0.10 0.04 0.09 0.28 0.03 0.15 2 0.11 0.38 0.06 3 0.13 0.20 0.22 Site 1 - Meadow Way at western end of proposed Woodacre flats project Site 2 - mouth of Woodacre Creek Site 3 - San Geronimo Creek before confluence with Woodacre Creek ● We tested only three sites in December. ● Because only three sites were tested in December, we had no idea what amount of human signal flowed into Woodacre Creek from above the Flats project or from the three tributaries that feed into it.

Observations - February 2017 Site Bird Dog Horse Human Pig Ruminant 1 0.05 0.02 0.04 0.15 0.03 0.07 2 0.22 3 0.08 4 0.06 5 0.01 0.00 6 0.11 0.18 7 8 9 10 0.19 11 0.25 12 Site 1 - Meadow Way at western end of proposed Woodacre flats project Site 2 - mouth of Woodacre Creek, below the Woodacre Flats Site 6 - tributary to Woodacre Creek at 256 Redwood Drive Site 10 - Montezuma Creek in Forest Knolls Site 11 - San Geronimo Creek in Forest Knolls, one mile downstream from Site 1 at Meadow Way ● At Site 2, there is a strong human source signal below the Woodacre Flats area, decreasing to a marginal source by Site 1 at Meadow Way. ● At Site 11, there is a strong human source signal one mile downstream from Site 1; human input is entering the Creek between San Geronimo and Forest Knolls.

● By Site 11 and Site 12, the human input signal has dropped off. Observations - May 2017 Site Bird Dog Horse Human Pig Ruminant 1 0.04 0.01 0.00 2 0.03 0.02 3 0.05 4 5 6 7 0.06 0.07 8 9 0.08 10 0.13 0.82 11 12 0.12 0.09 13 Site 10 - Montezuma Creek in Forest Knolls Site 11 - San Geronimo Creek, one mile downstream from Site 1 at Meadow Way Site 12 - Arroyo Creek ● There is no human input entering the creek except at Site 10, Montezuma Creek in Forest Knolls; this is the highest reading the lab has ever observed in the wild. ● By Site 11 and Site 12, the human input signal has dropped off.

● Site 11 shows a marginal human source signal. Observations - July 2017 Site Bird Dog Horse Human Pig Ruminant 1 0.04 0.01 0.00 2 0.03 0.05 0.07 0.02 3 4 5 0.09 0.06 6 7 n/a 8 0.44 0.10 9 10 11 0.12 12 13 Site 8 - unnamed tributary at 55 Park Street in Woodacre Site 11 - San Geronimo Creek, one mile downstream from Site 1 at Meadow Way ● Site 8 shows a very marginal human source signal of .10; Site 8 also shows a strong dog source signal of .44. This appears to be a one-time event. ● Site 11 shows a marginal human source signal.

Summary of observations: ● In December water flow was extremely high when the human source signals were detected in Woodacre. ● In February there was a strong human source signal detected at the mouth of Woodacre Creek and in San Geronimo Creek near Forest Knolls. ● Both in December and February, the strong human source signal at the mouth of Woodacre Creek dropped from a strong human source signal to a marginal human source signal at the Meadow Way site approximately 1 mile downstream. ● In February there was additional human input entering the creek between Meadow Way and Forest Knolls. ● There was no human signal detected in May or July with the exception of an unusual anomaly at Site #10 (Montezuma Creek) in May.

Conclusions: ● Further testing would be required to identify contaminant sources. This first round of testing has simply identified the problem areas. More specific testing will be needed to draw any final determination. ● We now have a clearer understanding of the impact septic systems have in our watershed. By undertaking this study we have identified both potential problem areas as well as shown how surprisingly clean our watershed is during certain times of the year. ● From previous studies we know there are problem septic systems throughout the Valley. However based on our study it does not appear septic systems are the severe watershed pollutant we thought they were. To achieve a proper and effective solution to the problems of pollutants in the watershed we need to understand exactly what the level of pollution is and where and what source it comes from.

Recommendations: ● We strongly recommend that Marin County Environmental Health Services (EHS) in conjunction with MMWD continue our work collaborating with Lawrence Berkeley Labs using the PhyloChip technology. ● Further testing and locating more specific sampling sites would be helpful to understand and identify the sources of human signals. ● We know some of the homes within the proposed Service District may not need to be served and some homes outside the proposed district have problems that clearly need to be addressed. ● If State and County monies are to be used for building sewage infrastructure, the entire Valley should be studied prior to designing any community sewage fixes. ● Localized sewage infrastructure would likely be ineffective at addressing contaminants throughout the San Geronimo Creek systems without the entirety of the San Geronimo Valley watershed being properly studied.