Septic is the main culprit
Nitrogen leaching from septic systems causes 70 percent to 85 percent of coastal saltwater eutrophication, the over-enrichment that produces algae, reduces underwater life and limits swimming, boating and fishing. Storm water delivers 5 percent to 8 percent of the nitrogen loading within estuary watersheds.
In more urban areas, like Hyannis Inner Harbor, storm water can contribute 10 percent to 15 percent of nitrogen load. Fertilizer loads from lawns also are in the 5 percent to 8 percent range.
In freshwater systems like ponds, lakes and streams, phosphorus is the key nutrient that causes excess growth of weeds and organisms. Phosphorus in wastewater is the main contributor to freshwater eutrophication, along with fertilizer runoff.
Cape Cod’s drinking water, drawn from one huge underground aquifer, also is showing rising nitrate levels, primarily from wastewater, as well as from fertilizers, agriculture and roadway runoff.
“The elevated nutrient levels are primarily related to land-use impacts associated with the increasing population within the coastal zone over the past half-century,” according to the Massachusetts Estuaries Project. “Coastal embayments, because of their shallow nature and large shoreline area, are generally the first coastal systems to show the effect of nutrient pollution from terrestrial sources.”
Not one solution, but multiple ones
One large, centralized wastewater treatment plant is not likely to be built on Cape Cod. Rather, water will be treated regionally and discharged into the ground within the watershed to recharge underground water supplies.
Smaller-scale treatment facilities already serve parts of Barnstable, Chatham, Falmouth and Provincetown. They may be expanded and upgraded.
Additional treatment plants will be built in populous areas to protect nearby coastal waters, particularly those narrow estuaries south of Route 28. New sewer lines, either gravity-fed or with pump stations, will link homes and businesses to the system.
Private satellite treatment systems at shopping malls, commercial laundries and other properties may be expanded. Advanced on-site systems at schools, nursing homes and offices may be upgraded.
A few cluster treatment systems may be included in the construction of compact dwelling units such as condominium complexes.
Some owners, especially in coastal locations not linked to a sewer system, may be required to install advanced on-site septic systems. Inland areas will continue to rely upon on-site septic systems.
Other approaches
Aggressive management of septic systems, such as mandatory five-year pump out and inspection, will prolong the life of septic systems, but not eliminate nitrogen.
Advanced on-site home septic systems that remove up to 65 percent of nitrogen are developing, but may not be efficient on single lots or for seasonal use when the biological denitrification system might be overloaded with nitrogen or starved for nitrogen. These systems require maintenance and inspection.
Conservation saves water, but the same amount of nitrogen is still flushed into the ground, only in higher concentrations.
Controlling future growth will not stop the nitrogen already flowing through sandy soils to coastal water bodies. Even if no more houses are built on Cape Cod, existing wastewater systems will continue to cause nitrogen overloading in coastal waters.
In some cases, poorly circulating coastal inlets could be widened or other measures undertaken to enhance natural cleansing of water areas, but they are likely to silt over and become narrow again in the future.
Costs in the billions
Estimates to upgrade wastewater treatment on Cape Cod range up to $3 billion. That includes $300 million in Chatham alone, situated at the elbow of the Cape and surrounded by coastal waters on three sides, which is leading the way in wastewater planning.
The per property cost of a town sewer system could be $30,000 or more, though it would be repaid over 20 or more years from various taxes and user fees.
Issues of fairness involve balancing construction costs among all stakeholders who benefit from cleaner waterways, as well as individual property owners who are connected directly to a new sewer system.
Funding is complex
Towns will borrow millions of dollars to construct wastewater treatment facilities, which will be repaid by taxpayers, through the annual property tax, a separate flush tax based on metered water use or number of bedrooms, or some other taxes.
Towns can apply for a limited number of low-interest loans through a Massachusetts revolving loan fund; otherwise, they must sell municipal bonds to raise capital. New legislation may allow towns to repay state loans at zero interest, making projects more affordable.
Construction of sewer collection pipes along roadways is funded mostly by amounts assessed on property served by the new sewer lines and partly by town taxes. These betterment assessments can be calculated by street frontage, per-dwelling unit or other factors. New legislation may allow property owners to repay betterment assessments over longer periods than the current 20 years, again making the project more affordable.
Hook-up charges for homes and business are paid by individual property owners. Annual operation of treatment facilities is funded through separate sewer user fees.
Individual on-site septic system upgrades and repairs are paid by property owners, and some may qualify for loan assistance through Barnstable County government. For an application, go to barnstablecountyhealth.org/CommSepticLoan/communityseptic.htm.
Published in Cape Business Sept/Oct 2007
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