North Carolina Division of Water Quality

North Carolina Division of Water Quality

Surface Water Protection Section – Program Development Unit

Watershed Assessment Team

November 10, 2008

Water Quality Monitoring Plan for Ledge, Little Ledge, and Holman Creeks

Lake Rogers and Little Ledge Creek Watersheds

Neuse River Basin

Catalog Unit # 03020201

HU 03020201060010

I. INTRODUCTION

The Ecosystem Enhancement Program (EEP) is currently developing an implementation strategy for several previously completed Local Watershed Plans in the Upper Neuse River basin, which includes Lake Rogers and Little Ledge Creek. There have been minimal water quality data collected in these watersheds. EEP has requested that the Watershed Assessment Team (WAT) collect baseline chemical monitoring of the watershed to assist in development of their implementation strategy in this area.

A. Major Findings of the Existing Data Summary and Monitoring Gaps

Most of the targeted watersheds in the Upper Neuse have been intensively sampled by state and local agencies, with the exception of the Lake Rogers watershed. This is likely due to the poor flow that has been previously noted in the streams feeding the reservoir (http://www.nceep.net/services/lwps/Upper_Neuse/lakerogplan.pdf). The poor flow characteristics are likely due to a combination of natural Triassic Basin stream characteristics, compounded by backup from Lake Rogers. There are also extensive wetland complexes along many of the tributaries. The data gap in this watershed was noted in a previous summary of data compiled by WAT for EEP.

B. Issues to be Addressed Through Monitoring

EEP has requested that baseline data be collected in this watershed. As the DWQ methods for benthic macroinvertebrate sampling are only applicable to flowing streams, these data cannot be collected. However, the issues that have been previously noted in this watershed primarily relate to nutrient inputs to Lake Rogers (severe eutrophication as well as nuisance growth of aquatic plant species) and sediment filling in the lake, so chemical monitoring of these parameters may prove more useful to the EEP implementation process. Active dredging is currently taking place in Lake Rogers to try to address some of these known issues and is expected to be completed in February 2009.

II. MONITORING APPROACH

A. Objectives of the LWP Monitoring Effort

The objective of this monitoring is to provide baseline instream nutrient and sediment levels for the two main tributaries feeding Lake Rogers (Ledge Creek and Holman Creek) and a tributary to Falls Lake (Little Ledge Creek).

B. Preliminary Reconnaissance and Watershed Evaluations

Three reconnaissance trips have been taken in this watershed by WAT staff. Stream access was fairly limited, as there are relatively few road crossings in the watershed. All reasonably accessible stream access points have been visited and all sites were found to be completely impounded or with extremely negligible flow. Poor flow appears to be due to backup from Lake Rogers and Falls Lake, as well as the swamp stream characteristics inherent in streams associated with wetland complexes. Additionally, this area is located in the Triassic Basin ecoregion, which is characterized by streams with poor flow throughout most of the year.

The watershed is primarily forested, though roughly a third of the land area is used for agriculture (row crops and pasture). There are some small areas of development in near the town of Stem, along the I-85 corridor, and along a portion of the Lake Rogers shoreline. There are extensive wetland complexes along Lake Rogers, Ledge Creek, and Holman Creek. Riparian areas appeared to be well buffered in most cases, by either wetlands or forested areas, except in the extreme upper portion of the watershed. A review of land use data (National Land Cover Database, 2001) and 2005 aerial photography indicated that agriculture with poor or non-existent buffers is much more prevalent in this area.

C. Primary Monitoring and Assessment Efforts

1. Monitoring sites and frequency of sampling: A total of five monitoring sites were selected, primarily based on accessibility and prevalent land use (Table 2). No monitoring will be done in Ledge Creek below Lake Rogers due to the active dredging of the lake. Sites will be sampled approximately weekly for a total of four sampling trips, under baseflow conditions (defined as >48 hours since last measurable rain) wherever possible, as weather and staff schedules allow.

Table 1: Proposed sampling locations

Site Code / Location / Latitude (dec deg) / Longitude (dec deg) / Drainage area (mi2)
HC1127 / Holman Cr. at SR 1127 (Brogden Rd.) / 36.1366 / -78.6969 / 9.5
HC1131 / Holman Cr. at SR 1131 (Tump Wilkins Rd.) / 36.1834 / -78.7106 / 1.8
LC1215 / Ledge Cr. at SR 1215 (Lyon Station Rd.) / 36.1762 / -78.7140 / 3.4
LC1004 / Ledge Cr. at SR 1004 / 36.1949 / -78.7291 / 1.8
LLC1724 / Little Ledge Cr. at SR 1724 (Northside Rd.) / 36.0910 / -78.7235 / 2.6

Figure 1: Lake Rogers sampling sites

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Table 2: Percent land use by category within sample site drainages

NLCD1 land use category / Holman Cr SR 1127 / Holman Cr SR 1131 / Ledge Cr SR 1004 / Ledge Cr SR 1215 / L. Ledge Cr. SR 1724
11 Open Water / 1.9 / 1.9 / 1.6 / 1.5 / 3.0
21 Urban- Low Intensity Residential / 2.1 / 5.5 / 3.5 / 4.2 / 1.1
22 Urban- High Intensity Residential / -- / -- / 0.2 / 0.1 / --
23 Urban, Commercial / 1.2 / 1.1 / 1.2 / 1.0 / 1.1
41 Deciduous Forest / 28.7 / 30.8 / 38.7 / 34.5 / 23.5
42 Evergreen Forest / 23.4 / 19.5 / 10.8 / 15.5 / 19.0
43 Mixed Forest / 13.7 / 10.7 / 8.0 / 12.2 / 11.2
81 Agriculture - Hay, Pasture / 6.2 / 8.3 / 8.0 / 7.1 / 11.3
82 Agriculture - Row Crops / 17.8 / 21.1 / 26.5 / 21.6 / 24.4
91 Woody Wetland / 4.7 / 1.0 / 1.5 / 2.3 / 5.5
92 Herbaceous Wetland / 0.2 / 0.1 / <0.1 / <0.1 / <0.1
1 National Land Cover Database, 2001 data, descriptions of categories available at http://www.mrlc.gov/faq.php

2. Monitoring activities and methods

Physical assessments and field metrics: Field measurements will be taken at all locations during each site visit. These will include water temperature (°C), dissolved oxygen concentration (mg/L), dissolved oxygen saturation (%), pH (standard units [SU]), and specific conductance (uS/cm at 25°C).

Water chemistry: Samples will be collected by WAT staff for analysis of ammonia, nitrite + nitrate, total Kjeldahl nitrogen, total phosphorus, and total suspended solids. Analyses will be performed by the DWQ Laboratory Section. All samples will be taken, preserved, handled, and hand delivered to the DWQ Central Laboratory for analysis in accordance with DWQ Laboratory section requirements (http://h2o.enr.state.nc.us/lab/qa/sampsubguide.htm). Reporting limits and analytical methods are shown in Table 3.

Table 3: Analytical methods and reporting limits

Parameter / Reporting limit / Analytical method 1
Total suspended solids (TSS) / 6.2 mg/L / APHA 2540D
Nutrients
Ammonia (NH3) as N / 0.02 mg/L / EPA 350.1, 350.2
Nitrite + nitrate (NO2+NO3) as N / 0.02 mg/L / EPA 353.2
Total Kjeldahl Nitrogen (TKN) as N / 0.20 mg/L / EPA 350.1, 350.2
Total Phosphorus (TP) as P / 0.02 mg/L / EPA 365.1
1 “APHA” refers to American Public Health Association, Standard Methods for the Examination of Water and Wastewater, 18th edition. “EPA” refers to US EPA standard methods.

III. QUALITY ASSURANCE

Quality assurance (QA) for chemical analyses will include collection of duplicate samples at one site during each sampling trip. There are no specific criteria for acceptance or rejection on the basis of relative percent differences between duplicates. The intent of these QC samples is to determine the total relative variability due to environmental, sampling, and analytical factors. However, if substantial differences are observed between duplicates, a decision will be made whether or not to reject the sample results for a specific parameter.

IV. PROJECT SCHEDULE

Sampling will be initiated by the middle of November 2008 and continue through approximately mid-December 2008 until a total of four sample sets have been collected. Weekly sampling will be attempted, though may be difficult due to laboratory restrictions and field staff scheduling issues due to Veteran’s Day and Thanksgiving holidays in November. The normal time required to receive analytical results from the DWQ Laboratory Section is four weeks. Allowing for delays due to holidays in November-December, it is anticipated that results will be received, compiled, and provided to EEP by January 30, 2009.

V. DELIVERABLES

The primary deliverables will be a written report summarizing findings, raw chemistry data, and digital photos of sampling locations. These will be provided to EEP by January 30, 2009.

VI. RESOURCE NEEDS AND BUDGET

The estimated resources needed (labor, travel & per diem, vehicle mileage, analytical costs, and supplies) are shown in Table 4. If additional resources are needed, this estimate will be revised as necessary in consultation with EEP.

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Table 4: Estimated costs for Lake Rogers chemistry monitoring

ITEM / PURPOSE
Salaries / Hours / Cost/hr / Item total
WAT staff field work, prep, data management, report writing / 56
Mileage / Miles / Rate/mi
Travel for sampling / 400
Analytical / No. Samples / Cost ea.
Analysis of water samples / 120
ESTIMATED TOTAL COST

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