What Storm Water Drains To Cowell Beach?
Site Overview
Storm water drains to Cowell Beach (except during dry season diversion) from:
Neary Lagoon
Laurel Creek(thru Neary)
Bay Creek(thru Neary)
Storm drain inlets between NearyLagoon and Cowell’s Beach
Beach Bummer List‐Why Now?
• The new sampling location, called “Cowell Beach West of Wharf,” has made Heal the Bay’s Top 10 Beach Bummer List the last 4 years.
• The other main Cowell Beach sampling point, “At the Lifeguard Station,” also has similar diminished water quality but has never been on the Beach Bummer list.
In 2010 the County permanently added a sampling point in front of the Neary Lagoon beach outlet vault due to increasing bacteria levels in 2008 at the regular Cowell Beach sampling point.
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County Environmental Health Services: Cowell Beach Monitoring
County EHS Beach Monitoring Locations
• Collects water quality samples along Cowell & Main Beaches
• Sampling done at least weekly all year round, and more frequently during summer
• Cowell Beach, West of Wharf, is sampling pt. #0488
County Environmental Health: • Conducts sampling at least weekly all year round, and more frequently during summer
• Cowell Beach “West of the Wharf” posted due to high bacteria levels
• Cowell Beach “At the Lifeguard Station” often has elevated bacteria levels in summer
• Cowell Beach “At the Stairs” typically very clean
Cowell Beach Monitoring
City also monitors weekly for bacteria (since 2010): • 3 Cowell Beach locations • 1 Main Beach location• 1 San Lorenzo River mouth station
Cowell Beach Monitoring
The Cowell Beach PuzzleUnanswered Questions:
• Why does the area near the beach outlet vault (West of the Wharf) typically have the highest bacteria levels?
• Why are bacteria levels much higher in summer?
• Data can vary wildly. Why?
• Have we found all controllable & human sources of bacteria?
• When and how much benefit will we see from isolating Neary Lagoon from Cowell Beach during the summer?
• City results also show very low bacteria during winter months
• Major sewer source unlikely as levels would be high year round
• In 2014, City added caffeine test as possible tracer for domestic sewage: NONE found so far
Cowell Beach Monitoring
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12/1/2013 1/30/2014 3/31/2014 5/30/2014 7/29/20145 sample Geo
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Mean (CFU
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FECAL COLIFORMS
Geo. Mean Limit Fecal
ENTEROCOCCUS
Geo. Mean Limit Enterococcus
Geometric Mean (5 sample) Bacteria Levels at Cowells Beach West
December 2013‐July 15, 2014
So, what’s the difference between winter & summer?
Cowell Beach‐Potential FactorsWhat’s different in summer?More• People using the beach• Birds on the Wharf• Sea lions on the Wharf• Pigeons below the Wharf• Seabirds, sometimes thousands, near‐shore following fish bait balls
• Upwelling in Bay: small fish, squid, jellyfish, krill• Trash on the beach
Cowell Beach‐Potential Factors
What’s different in summer? Also:• Neary storm drain lines tend to stagnate w/high bacterial growth (improvements in progress)
• River tends to be shoaled: winter flows may improve circulation & reduce pressure on groundwater
• Less wave action & storms
• Higher air & sand temperatures
• Off‐shore current changes
County of Santa Cruz
• Kelp may be a source of concern as rotting kelp can cause amplification of bacterial concentrations at Cowell Beach (kelp can serve as a substrate for bacteria).
• EHS has documented the potential for bacterial regrowth in decaying kelp. EHS findings supported by a San Diego study, by Weston Solutions, at a popular surfing beach which also came to this conclusion.
• Due to abundant offshore kelp beds, kelp continually washes up at Cowell Beach in spite of beach grooming efforts. Thus, there is residual bacteria in the water for at least several tidal cycles unless there is a significant swell/wave action.
Environmental Health Services‐ Kelp Findings
What has the City Done
• Found an offset residential bathroom sewer line joint. Sanitary waste discharged into rock wall along Pacific Ave., near 2nd St., flowing to street draining to Cowell Beach.
• Promptly fixed in August 2013.
Sewer Lateral Investigation
A significant sanitary waste source found &
eliminated
What has the City DoneIn 2013, cap placed on a storm drain grate inlet, near RR tracks under trestle bridge, inlet had been used as an outdoor bathroom.
Inlet flows into Neary Lagoon drainage lines exiting at Cowell Beach.
Area now patrolled regularly.
A sanitary waste source found & eliminated
Neary Lagoon: Dry Season Diversion to Wastewater Treatment Facility
• Summer diversion: 300,000‐500,000 gallons per day
• Lagoon water is treated and discharged via the plant’s effluent pipeline to the Pacific Ocean 1‐mile offshore Diversion since 1994
Neary Storm Summer Conditions
Even with diversion, some water remains in the large Neary storm drain pipes & stagnates, causing elevated bacteria levels in the pipes.
Water can seep out, from the uncapped pipelines, under the sand at the Cowell Beach outlet vault.
Thus, these storm drain lines are a potential source of bacteria at Cowell Beach.
IsolatingNeary Lagoon from Cowell Beach
• Installed slide gates to block flow from Neary to Beach (April 2014)
• Cleaned beach vault (October 2014)
• Cleaned & TV’d two Neary pipelines (October 2014)
• Install pipeline so water remaining between slide gates and beach can be pumped to Sanitary Sewer (to be constructed)
City Increases Investigation SamplingNeary Lagoon ‐Laurel Creek Upstream Monitoring
Conclusion to Date: • High bacteria likely from
pets & other non‐human sources
Results from 11 sets of samples: • Only one “hit” for caffeine in
June, not detected again • City continues investigation
City Efforts
• Expand monitoring at Cowell Beach and NearyLagoon for human DNA and caffeine.
• Monitor Cowell Beach further from shoreline.• Monitor Cowell Beach more this winter.• Study potential impacts from sand and kelp.• Study relationship between bacteria results and swell.
• Study near‐shore currents.
Further Work
Sewer Lateral Inspection Program
• Sewer lateral inspection program planned for residential & commercial properties
• Lateral inspection required at time of sale
• Anticipated start date: 2016
City Efforts
Cowell Beach‐ConclusionsCity has eliminated several direct sources of contaminationCity has also reduced impacts from Neary Lagoon drainage
system
It may take time to see improved testing results at Cowell Beach City plans to continue and expand testing at Cowell BeachExpand public interactions with local community
Presentation by Suzanne Healy and Steve Wolfman, Dept. of Public Works
Questions or For More Information: Please call Steve Wolfman:831‐420‐5428