What is a watershed?

A watershed is an area of land that drains all the streams and rainfall to a common outlet such as the outflow of a river, mouth of a bay, or any point along a stream channel. The word watershed is sometimes used interchangeably with drainage basin or catchment. Ridges and hills that separate two watersheds are called the drainage divide. The watershed consists of surface water--lakes, streams, rivers, and wetlands--and all the underlying ground water. All of the land that drains water to the outflow point is the watershed for that outflow location. Watersheds are important because the streamflow and the water quality of a river are affected by things, human-induced or not, happening in the land area "above" the river-outflow point.

What is a Nonpoint Source and Point Source?

Point Source: A Point Source discharge is a single identifiable source of pollution, such as a pipe or drain commonly discharged into drainage infrastructure & waterways.

Nonpoint Source: generally results from land runoff, precipitation, atmospheric deposition, drainage, seepage or hydrologic modification. Nonpoint source (NPS) pollution, unlike pollution from industrial and sewage treatment plants, comes from many diffuse sources. NPS pollution is caused by rainfall or snowmelt moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters and ground waters.

Nonpoint source pollution can include:

States report that nonpoint source pollution is the leading remaining cause of water quality problems. The effects of nonpoint source pollutants on specific waters vary and may not always be fully assessed. However, we know that these pollutants have harmful effects on drinking water supplies, recreation, fisheries and wildlife.

What is the Parish doing to protect my watershed?

The Louisiana Department of Environmental Quality (LDEQ) has monitored the ambient water quality of St Tammany Parish streams and lakes for decades.  The data gathered by LDEQ is utilized to determine impairments of waterways.  St Tammany Parish has implemented a Water Quality Sampling Plan which further documents the water quality conditions of St. Tammany Parish waterways, some of which were listed as impaired on the 2012 LDEQ Integrated Report for Dissolved Oxygen.  The Parish performs monthly in-situ water quality monitoring of up to 34 sites on St. Tammany rivers.  These are the ‘hot spots’ where some Water Quality Protection Area signs have been posted to heighten public awareness.  St. Tammany Parish personnel work closely with the State of Louisiana regulatory agencies to contribute water quality monitoring data and other relevant information to assist with important decisions about the health of state waters.  Parish personnel comment on public-noticed Clean Water Act Section 303(d) Impaired Water Lists

The Parish is also in the process of revising the Development Code of Ordinance.  The Parish wishes to encourage more green infrastructure to assist with both water quality and water quantity in the Parish.  Green infrastructure encompasses many practices that retain runoff on site and relies on the nature processes of infiltration and evapotranspiration, and uses soils as a filter to treat and manage stormwater.  The parish also encourages low-impact development (LID) measures which manage rainfall at the source using integrated site design techniques that are intended to replicate preexisting hydrologic site conditions.

There are numerous areas throughout the Parish that are owned and restricted from development by the Parish.  The majority of these areas of designated wetlands, floodplains or floodways.  The Parish continues to review their inventory for implementation of best management practices to assist with environmental health.

EPA Pollution Source Tracking Project:

The Parish has been awarded grant funding for Water Quality improvement projects through Lake Pontchartrain Basin Restoration Grant and EPA Gulf of Mexico Partnership Cooperative Agreements 2015.  St. Tammany Parish Department of Health and Human Services (DHHS) has a parallel CDBG grant to fund repairs/replacements of ATUs for Low-Moderate Income (LMI) residents in St. Tammany Parish.  The Parish has begun initial inspections in the Ozone Woods subdivision as part of the Pollution Source Neighborhood Tracking program, a Water Quality Area sign has been posted to at the entrance and exits to this subdivision to heighten public awareness.

Stormwater Pond Projects:

There are currently many constructed storm water detention and retention ponds that are maintained and monitored for water quality by the Parish.  Additionally, there are a number of ‘hot spots’ within the Parish waterways which are monitored for water quality as well.  These hot spots are areas which have shown through sample collection and analysis to potentially have more pollutant load than is desirable.

What is a TMDL?

The rivers, bayous and watersheds in St. Tammany Parish are subject to Total Maximum Daily Load (TMDL) criteria placed upon them by the Louisiana Department of Environmental Quality, (LDEQ), with approval by the U.S. Environmental Protection Agency.   The state of Louisiana has incorporated these TMDLs into their water quality plan and implemented waste load allocations on many of the watersheds in St. Tammany Parish.  As part of their water quality plan, LDEQ is requiring more stringent effluent limitations in their discharge permits, increased use of Best Management Practices and additional regulatory requirements of Municipal Separate Storm Sewer Systems (MS4).

The Parish has been engaged with LDEQ throughout the TMDL process and recently had a Watershed Management Study Report prepared through the Louisiana Coastal Protection and Restoration Authority (CPRA) to further delineate the individual watershed standings and needs moving forward. In response to the implementation of the TMDL program and the Watershed Study, St. Tammany Parish has developed a ‘Watershed Management Program’ with a goal to protect and enhance water quality in St. Tammany Parish through a targeted watershed approach. 

As part of the Parish Watershed Management Program, the Parish continues to work with LDEQ to better monitor, identify and place water quality standards/limits upon the unique waterways located within St. Tammany Parish.  The Parish is committed to making watershed impacts one of the criteria that is considered for all activities within the Parish moving forward. 

To better inform you, the citizens of St. Tammany Parish, about the Watershed Management Program implemented by St. Tammany Parish we have posted signs throughout the Parish where we have on-going water quality maintenance and/or monitoring locations.  Below is a list of sites and the details of each.  For further information regarding this program please contact the Watershed Coordinator in the Department of Planning Development - Engineering at 985-809-7448.

You can find out more information on the watershed you live in by following the link below: EPA – Surf Your Watershed   



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