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Nitrogen Management Strategies & Tools

Sub-pages: Nitrogen Management Origins | 1999 TMDL Recommendations | 2007 Model General Bylaw |

DEP's Massachusetts Estuaries Project

Background

Overview of Program
Oceancscience.net web site (primary host)
Overview of Program
DEP site

Overview of Program
Umass Dartmouth SMAST web site

DEP Fact Sheet
Covers TMDL issues

DEP's list of estuaries
Schedule subject to change

MEP 2001 Pilot Project documents
Has the original planned schedule.

Multi-town collaboration
DEP web page with links

Nitrogen Management Tools
A Cape Cod Commission Report

Restoring Estuaries
A DEP Links page

BB Estuary Reports

West Falmouth Harbor
Completed

Phinneys Harbor / Back River complex
Completed

Wareham River Estuary Complex
Anticipated Aug. 2007

New Bedford Inner Harbor
Anticipated Aug. 2007

Slocums and Little River Complex
Anticipated Aug. 2007

Status of the Buzzards Bay NEP's Nitrogen Management Strategy

In 1990, the Buzzards Bay NEP, a participant in the U.S. Environmental Protection Agency's National Estuary Program, developed a Total Maximum Annual Loads (TMALs) strategy to manage anthropogenic nitrogen inputs to coastal embayments in Buzzards Bay. This strategy was contained in the 1991 Buzzards Bay Comprehensive Conservation and Management Plan.

In 1992, the Buzzards Bay NEP established, in partnership with the citizens group the Coalition for Buzzards Bay, a water quality monitoring program to evaluate nitrogen loading impacts in Buzzards Bay. The purpose of this monitoring program was to not only document water quality conditions and trends in Buzzards Bay embayments, but to also evaluate the appropriateness of the specific nitrogen loading limits recommended in 1991.

This water quality data has proved highly useful to both managers and the public and this data has prompted action to manage both point and non-point pollution sources alike. However, until the late 1990s was a detailed evaluation undertaken of the monitoring program results with CCMP loading limit recommendations.

The 1999 report below represents that undertaking. While the data in the report supports the fundamentals of the Buzzards Bay NEP's management approach such as calculating mass loadings to land, and tailoring TMALs to bay volume and flushing, it also suggested that the recommended limits are too high, and in some cases need to be reduced by one half.

Currently, the Buzzards Bay NEP methodology for establishing nitrogen loading limits is being superseded by the DEP's Massachusetts Estuaries Project (MEP), which is projected to be complete by 2010. However, the Buzzards Bay NEP's nitrogen loading methods are nearly identical to that used by the MEP, and the spreadsheets in the section below can still be used for estimating watershed loadings. Furthermore, the BBP's recommended loading standards can still help guide land use decisions until better information is available through the MEP in the coming years. Town's can also consider our nitrogen model bylaws to implement MEP recommended loading limits.

Comments about this page should be directed to Joe Costa.

BBNEP 2000 Proposed Water Quality Standards

In 1999 and 2000, the Buzzards Bay NEP proposed the water quality standards in the table below to DEP (see 1999 and 2000 papers below) based on best professional judgment. These standards were proposed as surrogate measures of nitrogen loading, corresponding to the proposed TMALs for nitrogen identified for waters designated ORW, SA, and SB categories as proposed in our original nitrogen strategy. The table was developed empirically based on the correlations beween loadings and water quality response shown in the figures in the 2000 paper. Thus they represent the lowest value possible before dropping into the next lower category of "good" "fair" and "poor." In this sense they are not necessarily the ideal value for that category. The ideal goals for Buzzards Bay embayment water quality remain closer to the Eutrophication Index values shown in the table. All these values are based on mean summertime concentrations when critical conditions are most likely to occur. See Costa et al (1999) for definition of eelgrass to habitat ratio.

In the end, DEP and the Massachusetts Estuaries Project adopted a similar approach to establish TMDLs for Massachusetts embayments, but instead of using the simplified tiered strategy proposed by the BBNEP in the early 1990s, new, more sophisticated embayment-specific modeling methods that had become available are now being used that incorporate flushing, loading, and other factors that defines each embayments response to nitrogen loading and specific target total nitrogen and chlorophyll concentration, and eelgrass cover goals goals.

	Excellent	"Good to Excellent "	"Fair "	"Eutrophic "
Parameter	100 pts Eutrophication Index	ORW	SA	SB
Eutrophication Index	100	65	50	40
Alt. Eutrophication Index (no 02)	100	65	45	30
Total N (ppm)	0.28	0.43	0.54	0.65
Chl a (g/l)	3.	5.0	7.0	9
Secchi depth (m)	3.0	1.9	1.5	1.3
Eelgrass to core habitat ratio	Not incl., but perhaps 1.2	0.8	0.5	0.3