The MDC's water comes from surface water sources in watersheds that cover approximately 89.7 square miles. These include the watersheds that feed the 30-billion gallon Barkhamsted Reservoir and the 9.5-billion gallon Nepaug Reservoir in northwestern Connecticut, as well as the smaller watersheds associated with the West Hartford Reservoirs and Reservoir 6.

Although the majority of these watershed areas are relatively rural, which reduces the chance of pollution, the District conducts an aggressive source protection program to further ensure the quality of its water supplies. This is important because the District owns and manages only a portion of the watershed land draining to the reservoirs.

Source water is untreated water that is used to supply public drinking water. Natural processes and human activities that occur within a watershed drainage area can greatly impact the quality of that source water.

The MDC is very fortunate to have heavily forested watersheds, which help safeguard the water supplies by acting as a natural filter and buffer to potential contaminants. A well managed forested watershed is the first line of defense for protecting water from pollution and maintaining high quality drinking water.

Forest lands intercept precipitation, promote water infiltration, reduce storm water runoff, moderate stream flows, recycle nutrients and chemicals, stabilize soils, reduce soil erosion and sedimentation, and provide clean water.

As watersheds become more urbanized and the percentage of impervious surface coverage increases (due to buildings, roads, driveways, and parking areas), stormwater runoff increases, which can transport pollutants and degrade downstream waters. Generally, water quality decreases as the amount of impervious coverage increases within a watershed area.

Water travelling over the surface of the land or through the ground can carry substances such as soil particles, salts, metals, hydrocarbons, bacteria, fertilizers and pesticides that can contaminate water supplies. It is therefore very important to monitor land use activities in the watersheds and protect the water at its source.

The District conducts an annual sanitary survey of watershed properties, which is required by the Connecticut Department of Public Health. The MDC's watershed inspector visits residences, businesses and farm properties located within the watershed areas to identify conditions that may adversely affect drinking water supplies. The watershed inspector checks for signs of septic system failure, leaking fuel oil tanks, soil erosion and sedimentation issues, illegal discharges, improper storage of chemicals, pesticides and animal wastes, illegal dumping, and other conditions that have the potential to affect water quality.

The District also works closely with watershed towns on land use planning and development issues that may affect water supplies. The MDC's Watershed Management Unit reviews development proposals that come before watershed towns and when appropriate, submits comments to encourage practices that protect reservoir water quality. Inspections are also conducted during the year to monitor the progress of development projects.

Reservoirs and tributary streams are also routinely sampled and monitored for water quality. Water samples are collected daily and delivered to the MDC's Water Analysis Laboratory where physical, chemical and biological analyses are conducted to identify potential drinking water contaminants.

One of the most important measures that can be taken to strengthen source protection efforts is to permanently protect watershed lands. The District has made a strong commitment to permanently protect additional watershed lands through the establishment of a Land Acquisition Program and Fund. As a result, several key parcels have been acquired to date.