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Memorandum
To: Mr. Frank Clifton, County Manager
From: David Stancil, DEAPR Director
Tom Davis, Water Resources Coordinator
Date: November 15, 2011
RE: Surface Water Quality Monitoring
On August 30, 2011 the Board of Commissioners requested information regarding the
potential monitoring of nutrient loading in surface waters exiting the County at the
County line (also known as "jurisdictional loading"). That request was followed-up by a
letter from Chair Pelissier to the Board dated September 15, 2011 regarding direction to
staff. This memorandum provides background information on this topic and includes
discussion of various methods of estimating nutrient loading.
Background
Interest in measuring water quality and determining the concentrations of nutrients in
surface waters in Orange County has been growing for several years. Recent
enactment of the state's nutrient management rules in the Triangle Region has certainly
heightened interest in this issue. Nutrients, namely nitrogen and phosphorus, are
added to surface waters as a result of stormwater runoff from development (including
roadways and other impervious surfaces), agricultural activities, point source discharges
(including wastewater treatment plants), and atmospheric deposition. Nutrients from
other sources such as on-site wastewater systems can be added to groundwater, which
can then, in turn, impact surface waters. Finally, forested lands can also be a source of
'The memorandum asked DEAPR staff to "provide an update/memorandum...with background
information, analysis, potential monitoring location, potential costs and recommendations." Since this
discussion came up as part of the Nutrient Management Rules discussion on August 30, staff interpreted
this direction to request a program targeted to monitoring for nutrient loading, as opposed to a more
global water monitoring program on all streams and a wider range of water quality parameters.
Orange County Department of Environment, Agriculture, Parks & Recreation
PO Box 8181, Hillsborough, NC 27278
Phone: (919) 245-2510 Fax: (919) 644-3351
2
nutrients to surface waters. All of these sources can contribute to the total quantity of
nutrients carried by surface waters, which is often termed the nutrient "load".
In 2004, the state Ecosystem Enhancement Program of NC DENR published the
Morgan Creek Local Watershed Plan: Detailed Assessment Report. This publication
included estimates of nutrient loading to both University Lake and Jordan Lake from the
surrounding watersheds. Nitrogen delivered to Jordan Lake ranged from a low of 1.64-
2.44 pounds/acre/year in the more rural areas of the watershed to 6.31-6.84 pounds/
acre/year in the more developed areas (Chapel Hill and Carrboro). Please note that
nutrient loads delivered to Jordan Lake are likely to be slightly lower than the loads
exiting the County due to naturally occurring processes including sorption and decay.
Estimating Nutrient Loading
The simplest method of estimating nutrient loading involves the use of a basic
areal loading rate spreadsheet tool. GIS could be used to determine the total
area of the county in each of several different categories of land uses, such as
medium density residential, etc. Nutrient export rates, such as those included
above, could then be assigned to the various land uses and used as input in a
spreadsheet, producing nutrient export estimations for each land use type. The
estimated values could be summed by watershed, river basin or jurisdiction. This
method would be somewhat limited, however, since it does not include naturally
occurring processes such as nutrient decay or sorption, for example.
• PLOAD (Pollutant Load) is a slightly more involved screening-level GIS-based
model, such as that described above, that could be used to determine loading in
watersheds.. It is likely that a consultant could use this model to estimate nutrient
loading for Orange County for less than $10,000.
• Amore complex distributed area model could also be used to estimate County-
wide nutrient loading. Such a model would utilize available water quality
sampling data as well as stream gage flow information as input. A consultant
could use SWAT (Soil and Water Assessment Tool) or a similar model to
estimate nutrient loading for Orange County for a fee of approximately $30,000.
Another alternative for examining the nutrient load exiting Orange County
involves recent activities undertaken by the Upper Neuse River Basin
Association (UNRBA). The Falls Lake Nutrient Management Rules (Falls Rules),
which became effective in January 2011, include an opportunity for additional
information to be provided to the Environmental Management Commission
(EMC) by 2024. The UNRBA is currently finalizing the selection of a consultant
to begin working on issues that are geared toward modifying Stage II of the Falls
Rules. The consultant will be required to compile and review existing water
quality data collected in Falls Lake and the surrounding watershed. In addition,
the consultant will compare nutrient loading estimates for tributaries and
Orange County Department of Environment, Agriculture, Parks & Recreation
PO Box 8181, Hillsborough, NC 27278
Phone: (919) 245-2510 Fax: (919) 644-3351
3
jurisdictions in the Falls Lake watershed. This work will be performed so that the
consultant can inform the UNRBA members as to which model appears to
function best for estimating loading in the Falls Lake tributaries. The consultant
will also detail the available methodologies for estimating jurisdictional nutrient
loading. Finally, the consultant will use this information to complete, as an option
to UNRBA members upon their request, estimates of jurisdictional loading for the
baseline year of 2006. It is likely that one end result of this process will be the
uniform application of a single advanced model to estimate nutrient loading for
the tributaries of Falls Lake as well as for the jurisdictions present in the Falls
Lake watershed for the baseline year of 2006. It is expected that the work
described herein will be completed in 2012 as a result of the timetable dictated in
the Falls, Lake Rules. The cost of completing these tasks will be paid for by
UNRBA dues. The optional tasks described above will be completed upon
request at an additional cost to UNRBA members.
• Similarly, the Nutrient Scientific Advisory Board (NSAB), which is currently tasked
with implementing the existing development portion of the Jordan Lake Nutrient
Management Rules, is working to determine how best to re-model nutrient export
in stormwater in the Jordan Lake watershed. The NSAB expects to select a
consultant to complete the updated modeling of this watershed in the very near
future. This work is expected to be completed in 2012 and funded by DWQ.
Recommendation
It is likely that the UNRBA process as described above will produce a very useful
estimation of jurisdictional nutrient loading for the Upper Neuse River Basin. Similarly,
the NSAB re-modeling of the Jordan Lake watershed should also yield useful nutrient
export information for this basin. For these reasons, staff recommends utilizing these
on-going efforts as sources of jurisdictional loading information.
Please let me know if I can provide further information on this topic.
cc: Gwen Harvey
Craig Benedict
Rich Shaw
Orange County Department of Environment, Agriculture, Parks & Recreation
PO Box 8181, Hillsborough, NC 27278
Phone: (919) 245-2510 Fax: (919) 644-3351
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BERNADE 77E PEUSS/ER, CHsVR ORANGE COUNTY BOARD OF COMMISSIONERS
STEVE YUHASZ. VICE CHAIR
VALERIEP. FDUSHEE POST OFFICE BOX 8181
ALICE M. GORDON 200 SOUTH CAMERON STREET
PAM HEMMINGER
B.aRRYJACOBS HILLSBOROUGH, NORTH CAROLINA 27'278
EARL MCKEE
September 15, 2011
Dear Commissioners,
\f~' a~~
At the Board's August 30, 2011 work session, Commissioner Jacobs brought forth two
petitions and these were to be reviewed by the ChairNice Chair/Manager at agenda review.
The two petitions brought forth were:
1) Review the possibility of the State initiating an update of the Eno River Capacity Use
Agreement
2} Review the possibilities of the County initiating a program to monitor water quality of
the County line
After review of these petitions, the ChairNice Chair/Manager have directed staff to do the
following:
1) Engineering staff has been asked to provide a repor#/memorandum to fhe Board
on: a) the most recent Eno River Capacity Use Agreement annual stakeholder
meeting noting the topics discussed, including possible discussion that may have
occurred on an potential Agreement update, IF ANY; b) any challenges that would
be encountered to pursue an update; c) potential costs and responsibilities for
those costs among the State/parties; and d) any comments/suggestions staff may
have regarding the Agreement/potential update/etc. To come back as an
Information Item on future regular meeting BOCC agenda.
2) DEAPR staff has been asked provide an update/memorandum to the Board with
background information, analysis, potential monitoring locations, potential costs,
and recommendations. To come back as an Information Item on future regular
meeting BOCC agenda.
This fetter will be provided as an Information Item on the September 20 , 2011 agenda
for public information.
Regards,
Bernadette Pelissier, Chair
Board of County Commissioners
CC: Frank Clifton, County Manager
Craig Benedict, David Stancil, Tom Davis, Kevin Lindley, Gwen Harvey, Perdita
Holtz
www.co.oranae.nc.us
Protecting and preserving -- People, Resources, Quatity of Life
Orange County, North Carolina -You Count!
(919) 245-2130 • FAX (919) 644-0248
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Attachment B
Existing Water Quality Monitoring Programs
Currently, several organizations are monitoring surface water quality in Orange County.
• The Town of Hillsborough samples the Eno River for a few parameters in order
to demonstrate compliance with the National Pollution Discharge Elimination
System (NPDES) permit for its wastewater treatment plant.
• The Upper Cape Fear River Basin Association conducts routine water quality
sampling and analysis of Morgan Creek as part of the Orange Water and Sewer
Authority (OWASA) NPDES compliance program.
• The City of Durham samples a few locations in Orange County, in addition to
many locations within the City limits, to document background water quality
conditions.
• The United States Geological Survey (USGS) conducts water quality sampling
of University Lake, Cane Creek Reservoir and the West Fork on the Eno
Reservoir as part of the Triangle Water Supply Monitoring Project (TAWSMP), of
which Orange County is a founding member. In addition, the USGS has
collected water samples at the stream gage on the Eno River in Hillsborough
since the 1930s.
Limited sampling is conducted in Orange County by the North Carolina Division
of Water Quality (DWQ). DWQ periodically (once every 5 years) samples
benthic macroinvertebrates and fish populations at a few locations. This is done
to document water quality conditions for Use Support Assessment, which results
in the assigning of stream ratings to individual stream segments. Unfortunately,
some of the stream monitoring performed by DWQ is actually completed in
Chatham County, and the resulting stream rating is projected upstream into
Orange County. While DWQ samples at more than 300 locations across the
state through their Ambient Monitoring System (AMS), no such sampling
locations are present in Orange County.
• The Town of Chapel Hill sampled several surface water locations for chemical
parameters and macroinvertebrate populations from 1994 through 2008 but is
currently sampling only for benthic macroinvertebrates.
Orange County Department of Environment, Agriculture, Parks & Recreation
PO Box 8181, Hillsborough, NC 27278
Phone: (919) 245-2510 Fax: (919) 644-3351