The water quality in New York harbor is better today than it has been in over a century thanks to billions of dollars NYC invested in the sewer system and wastewater treatment plants. The NYC water supply system is a unique network of reservoirs, aqueducts and water mains. Although the city has abundant water supply for the foreseeable future, water quality and supply network face some serious challenges. Some of the critical elements of the city's water supply system cannot be taken out of service for long term repair and maintenance. Also, as development continues to impinge on the upstate watersheds, the city has to make great efforts to protect source waters. Since the Clean Water Act was established in 1972, the city has spent over $35 billion to improve its water quality. These expenditures resulted in enhanced sewage handling and treatment while decreasing the level of pollution, bacteria and water-borne litter and debris. The city has also improved the capture rate of combined sewer overflows (CSOs) from approximately 18 percent in 1980s to 73 percent today. The amount of sanitary waste in CSOs has declined from 30 percent in 1994 to 12 percent in 2008, which means that current overflows primarily consist of rainwater. Since PlaNYC was adopted, the city has invested additional $2 billion to further improve wastewater treatment. The result of these efforts is that the water quality in New York Harbor is the highest than at any time in the past 100 years and has reached the point where significant portions of the city's surrounding waters are available for recreation: over 95 percent of New York Harbor is available for boating while 14 miles of public beaches in the Bronx, Brooklyn, Queens and Staten Island provide access to swimwaters. The city monitors the Harbor's water quality by using various measures on an annual basis. Two of the most universal indicators of harbor health are the average dissolved oxygen levels and fecal coliform concentration levels. Sufficient concentration of dissolved oxygen is crucial for the respiration of most aquatic life forms, including fish and invertebrates such as crabs, clams and zooplankton. Over the past 20 years surface and bottom water dissolved oxigen levels in New York Harbor have been above the state standard and continue to rise, indicating that the harbor is suitable to most aquatic life. Fecal coliform concentrations are indicators of sewage related pollution. Over the past 20 years the concentration levels have been below state standards with occasional spikes attributable to rain events. As a matter of fact, the biggest remaining challenge today is managing stormwater, which can overwhelm sewers and cause CSOs that discharge a diluted mix of sewage and surface runoff to New York City waters.Currently the city focuses on two types of investments to improve the overall water quality: hard infrastructure and green infrastructure. NYC continues to enhance its hard infrastructure. It expands capacity of existing wastewater treatment plants and is currently in the process of constructing two new facilities. Those will capture and hold CSOs until storms pass and then pump them in wastewater treatment plants. The first, a $137 million Alley Creek CSO-retention facility in Queens, will store and capture combined stormwater and wastewater that previously was discharged into Alley Creek and Little Neck Bay during heavy rainfall. This will lead to increased dissolved oxygen concentrations, decreased contaminant levels, and fewer plastic bottles and other litter discharged into the creek and bay. The CSO-retention facility will reduce the overall volume of CSOs discharged to Alley Creek from approximately 246 million gallons per year to 112 million gallons per year. It is scheduled to be operational in 2011. The second, a $427 million facility in Paerdegat Basin in Brooklyn, will capture 50 million gallons of CSOs from a drainage area of approximately 6,000 acres. Construction of Paerdegat Basin Combined Sewer Overflow (CSO) retention facility is scheduled to be completed in 2012. NYC also attempts to shift its future water quality improvement efforts towards green infrastructure. The efforts will be coordinated by Sustainable Stormwater Management Plan that was introduced in 2008. The major purpose of the plan is to identify opportunities to use vegetation and permeable surfaces to keep water out of the city's sewer system. Controlling stormwater at the source provides cost saving opportunities versus investing in hard infrastructure. It also offers other benefits like improved air quality and cooling effect. The city has currently launched over 30 sustainable stormwater pilots to test some of the green initiatives in stormwater handling. NYC also makes strides to protect and restore wetlands within the five boroughs. Wetlands are invaluable natural creations that filter pollutants, protect from floods and provide wildlife habitats. The city has already carried out field inspection of 373 acres of properties in all five boroughs, acquired a 9-acre property in Jamaica Bay's Broad Channel that directly adjoins to the Big Egg Salt Marsh Complex, acquired a 3-acre privately owned waterfront property in Rockaway and secured $20 million federal funding for the restoration of 38 acres of wetlands and natural grasslands in Paerdegat Basin. The NYC water supply system is a complex infrastructure that was mostly built before World War II. Much of this infrastructure hasn't been clodsely inspected since opening. The current water supply network is comprised of Croton, Catskill and Delaware- the three systems that provide drinking water to the City and upstate communities. Without the ability to take portions of the system offline for maintenance and repair, its long term reliability can be challenged. The water supply network also faces constant pressure fromdevelopment proposals near the drinking water sources. Over the next ten years the city is planning to spend $6.7 billion to upgrade the network and protect the quality of drinking water. These capital expenditures helped NYC to achieve a 15 percent control over the watershed through direct ownership or conservation easement. Another 19 percent is controlled by the State of New York. The city also invested $24 million to construct new wastewater infrastructure in communities with substandard septic systems and to help watershed homeowners repair or replace failing septic systems. Major projects are underway to improve the quality of drinking water - a new water filtration plant for the Croton system and an ultraviolet desinfection plant for the Catskill and Delaware systems are scheduled to open in 2012 and 2013 respectively. Another critical objective identified by the city is to create a reliable back up system for NYC's aging network. Creating redundancy for the aqueducts will allow the city to conduct crucial repairs without interrupting water supply. Some of the major repair work is planned for the 85 mile long Delaware Aqueduct - the longest continuous tunnel in the world. The Aqueduct has been having steady and continuous water leaks since 1980s. These water leaks cost the city 10 to 36 million gallons of water per day. Eliminating them is essential since the Delaware tunnell supplies 50 percent of NYC's water. NYC's other priority is to modernize in-city water distribution. Construction of Water Tunnel No3 is one of the largest capital projects in the city's history - its total cost is estimated at $6 billion. Begun in 1970, Water Tunnel No3 is expected to be fully operational by 2020. The completion of this project will allow the city to carry out a much needed analysis and repair of Water Tunnels No1 and No2.