Watershed-Based Permitting Case Study

Lewisville Vl/^"tershed,

T ex as

City of Denton Watershed Protection Program

Permitting Authority:

Texas Commission on Environmental Quality

Permittee Point of Contact:

Ken Banks
(940) 349-7165

Permit Types: Individual and general permits to publicly owned
treatment works to control discharges of industrial process
wastewater and industrial, municipal, and construction storm water

Permit Information:


Pollutants of Concern in Watershed:

Nutrients, ammonia, pesticides/herbicides, and sediment

Permit Issued: Various dates


The Lake Lewisville watershed has been experiencing
significant development pressures, so in 2001 the city of
Denton, Texas, the largest city in the watershed, devel-
oped several watershed-based programs to address water
quality concerns and storm water permitting require-
ments. While Lake Lewisville is not currently listed as
impaired under the state's Clean Water Act (CWA) section
303(d) list, the city has taken some proactive measures
to protect the water quality of the lake. The city has lever-
aged multiple funding sources for this. Specifically, Den-
ton has implemented a water quality monitoring program,
employed land use planning and management tools, and
disseminated critical information to the public aimed at
changing residential land use practices.

Watershed Approach Background

Lake Lewisville is an important source of drinking water
and recreation, and Denton is the largest municipal-
ity within the Lake Lewisville watershed. Although Lake
Lewisville is not currently impaired, it is under risk of
impairment due to development and other pressures in
the watershed. The Texas Commission on Environmental
Quality (TCEQ) ranked Lake Lewisville 96th out of 102
lakes in the state for eutrophication. In addition, increas-
ing development has caused Lake Lewisville to have the
highest number of new or amended wastewater permits of
any lake in the state. Several of the watersheds draining
to Lake Lewisville are rapidly developing and face height-
ened water quality concerns. To address overall impacts
to Lake Lewisville and to comply with National Pollution
Discharge Elimination System (NPDES) Phase II storm
water requirements, Denton initiated a Watershed Protec-
tion Program.

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Watershed-Based Permitting Case Study

L-^Ke Lewisville V/fibersUed, Tex&.s

Before initiating its Watershed Protection Program in 2001,
the city and its partner, the University of North Texas (UNT),
received a grant in 1998 from the U.S. Environmental Pro-
tection Agency's (EPA) Environmental Monitoring for Public
Access and Community Tracking (EMPACT) program. The
purpose of the grant was to establish a program called ECO-
PLEX (Environmental Condition On-Line Dallas-Fort Worth
Metroplex). Among other environmental indicator tools, this
project established two real-time water quality monitoring
locations and a Web site to provide public access to the
data (see the ECOPLEX sidebar below). The city based its
Watershed Protection Program on the concepts employed
under the ECOPLEX project; therefore, the program includes
an extensive watershed-based monitoring component, land
use management element, and public education.


The objective of the ECOPLEX project is, by using both in-
novative and proven environmental monitoring technologies,
to collect real-time environmental data to inform the citizens
of Denton, the Elm Fork watershed, and the Dallas/Fort
Worth metropolitan area of current, historical, and near-term
forecasts of environmental conditions. Biological, physi-
cal, and chemical data are continuously measured at Lake
Lewisville and telemetered to UNT for analysis and display
in near real-time on the Web site (www.ecoplex.unt.edu).
The parameters measured include clam gape, temperature,
dissolved oxygen, conductivity, turbidity, pH, depth, fluores-
cence, and chlorophyll a). These parameters or indicators
are monitored at a site in Lake Lewisville and a site in Pecan
Creek—a tributary to Lake Lewisville.

The biological data collected include data on clam behavior
(Corbicula fluminea). A colony of clams has been placed
at the monitoring locations along with sensors to detect
valve movement (gape). When conditions become unfavor-
able to the clams, such as when the water contains high
concentrations of toxic pollutants, the clams tend to close
their valves. When this behavior is observed, an automated
water sampler is activated. UNT then analyzes the sample
to evaluate toxicity and identify the contaminants.

Watershed Approach Strategy

The city's Watershed Protection Program has three com-
ponents: monitoring, land use planning and management,
and public information dissemination. In addition, the city
recently received a CWA section 319 grant from TCEQ and
is developing a Watershed Protection Plan using existing
watershed-based monitoring and management techniques
implemented under the Watershed Protection Program.
(TCEQ administers the section 319 program in Texas for
nonagricultural management projects.)

Watershed-Based Monitoring

There are three main watersheds in Denton: Cooper Creek,
Hickory Creek, and Pecan Creek. City staff further delin-
eated approximately 71 subbasins and established sampling
stations within each. The city began monitoring these 71
subbasins during base-flow conditions in January 2001. It
also established four permanent monitoring stations near the
ends of the three major watersheds, above the confluence
of the watersheds with Lewisville Lake. These permanent
stations include a station both above and below the Pecan
Creek Water Reclamation Plant's outfall. The city conducts
monthly sampling at each of more than 70 stations. (Pesti-
cide monitoring is conducted March-August.) The city has
installed in-stream monitoring devices, performs quarterly
storm water monitoring, and performs biannual biological
monitoring, specifically for macroinvertebrates. Real-time
monitoring is conducted in one subbasin as well (i.e., the
Lake Lewisville subbasin).

The city collects and analyzes approximately 400,000 indi-
vidual measurements annually to assess water quality condi-
tions in the watershed. In addition, it conducts 900-1,000
dry-weather screening inspections each year to detect illicit
discharges, such as pesticide and construction runoff, to
establish baseline conditions and to prioritize issue areas or
locations of concern.

Watershed-Based Management

The city layers the data collected through watershed moni-
toring on an existing geographic information system (GIS)
and uses the tool to target areas of greatest water quality
concern and graphically display spatial and temporal trends
to determine the quality of the city's surface water. For
example, the city used the system to determine that Hickory
Creek, of all the subwatersheds in the Lake Lewisville
watershed, discharges the greatest amounts of total nitro-
gen, total phosphorus, and total suspended solids. The city
subsequently applied for a section 319 grant from TCEQ to
address the problems in Hickory Creek. (For more informa-
tion, see the Watershed Approach Highlights section.)

In addition, using GIS, Denton performed analyses during
the initial monitoring efforts to determine which land uses
(zoning categories) were associated with certain parameters.
In general, Housing and Planned Development land uses
were consistently associated with elevated conductivity and
total dissolved solids concentrations. High turbidity values
were consistently associated with the Planned Development
land use category. The city assumes that this relationship is
caused by the active construction occurring in those areas.
Total Housing, Total Business, and Planned Development
land use categories were consistently associated with high
levels of the pesticides diazinon and chlorpyrifos. High herbi-
cide (triazine) concentrations were most strongly associated


Watershed-Based Permitting Case Study

L-^Ke Lewisville V/fibersUed, Tex&.s

with Planned Development land use as well. The city hy-
pothesized that high pesticide and herbicide concentrations
were likely due to chemical management of residential and
commercial lawns.

From this information, the city determined that more public
education was needed regarding nonpoint source pollution,
specifically to provide the public with tips on reducing pesti-
cide runoff and other runoff to the creek.

Watershed-Based Public Information Campaign

The city has created a "Find Your Watershed" Web page for
residents to locate their watersheds and learn about water
quality impairments (http://gisweb.cityofdenton.com/
website/watershedlaunchpage.htm). The Web page also
provides information to residents to answer three basic
watershed questions: "What is a watershed?" "Why is it
important?" and "What areas of concern do we look for in
the watershed?"

The Web page was designed to encourage public interest
and participation in the health and maintenance of Denton's
watershed and drinking water resource. The Web page al-
lows residents to enter a street address and generate a map
of their subwatershed displaying various layers of data. The
Web site also includes graphs depicting long-term trends in
water quality levels of pH, dissolved oxygen, salinity, turbid-
ity, several pesticides, and conductivity, as well as monthly
values for each.

In addition to providing overall trend information to residents
on its Web site, Denton hopes to include monitoring data
from all of its permanent stations on the ECOPLEX Web site
in the near future. It also hopes to include UNT real-time
data on the site.

Watershed Protection Planning

In 2005 TCEQ awarded a section 319 grant to Denton enti-
tled "Control of Nonpoint Source Loads in the Hickory Creek
Sub-basin of the Lake Lewisville Watershed as a Component
of a Watershed Based Water Quality Trading Program."
The primary goal of this project is to reduce sediment and
nutrient loads to the Hickory Creek arm of Lake Lewisville
by rewarding management activities (i.e., best management
practices or BMPs) that enhance surface water resources.
The knowledge gained, however, eventually will be applied
throughout the Lake Lewisville watershed. This project
builds on the knowledge the city gained from a 2004 CWA
section 104(b)(3) grant project titled, Incentives for Action:
Incorporating Trading Options into Watershed Improvement
Plans for Lake Lewisville. The section 319 grant is expected
to last about 40 months, with the first half focusing on
assessment and monitoring and the last half focusing on
implementing BMPs, post-BMP monitoring, and evaluating
incentives for nonpoint source pollution controls.

The Hickory Creek watershed is in Denton County. The area
is mainly rural, containing large amounts of open space and
bottomland hardwood forests. However, development is
increasing within the watershed, creating increases in runoff
volumes and reductions in open space. Past TCEQ monitor-
ing efforts have resulted in it placing Hickory Creek on the
303(d) list of impaired waters as a nutrient enrichment
concern due to high ammonia concentrations from unknown
point and nonpoint sources.

The objectives of the section 319 project are, through
stakeholder dialogue, information exchange, and targeted
research, to do the following:

4 Create an agricultural and urban partnership through
development of a Watershed Protection Plan

4 Identify existing storm water management BMPs that
can be upgraded to achieve water quality objectives

4 Implement water quality BMPs in the Hickory Basin
that demonstrate sediment and phosphorus control

4 Identify incentive-based approaches to enhance the
rate of BMP implementation

4 Establish a water quality approach that can be ex-
panded throughout the Lake Lewisville watershed.

In June 2006, the city submitted a draft BMP Implemen-
tation Plan describing the BMP demonstration projects it

Watershed Protection Plan Elements

As part of the section 319 grant project, the city is required

to develop a Watershed Protection Plan for Hickory Creek.

The plan is to include the nine EPA Watershed Protection

Plan elements:

4 Identify the causes and sources of pollutants

4 Estimate load reductions

4 Describe the nonpoint source management measures
that will need to be implemented

4 Estimate the amounts of technical and financial
assistance needed

4 Describe the information and education component

4 Estimate a schedule for implementing the nonpoint
source management measures

4 Describe the interim, measurable milestones

4 Develop a set of criteria that can be used to determine
whether loading reductions are being achieved

4 Describe the monitoring component


Watershed-Based Permitting Case Study

L-^Ke Lewisville V/fibersUed, Tex&.s

proposes to implement in the Hickory Creek subwatershed.
The city has proposed installing BMPs on city-owned proper-
ties: an airport, fire station, and public park. The total capi-
tal cost to implement BMPs at all three sites is estimated
to be approximately $100,000, not including monitoring
or engineering costs. The plan estimates that the average,
weighted-cost for removing pollutants will be $427 per ton
of sediment, $559 per pound of phosphorus, and $73 per
pound of nitrogen.

The city's next steps in the BMP implementation process will
be to perform monitoring before designing and constructing
the BMPs. The city plans to continue monitoring activities
during the installation process.

The city is also in the process of identifying incentives for
private entities to implement BMPs within the watershed.
Water quality trading is being considered as one option.

Factors Considered During Development

Denton is implementing the Watershed Protection Program
to proactively improve water quality in the watersheds that
drain to Lake Lewisville. The lake is not listed as impaired
on the state's section 303(d) list, and no total maximum
daily load (TMDL) has been developed for it or any of the
city's receiving waterbodies. Denton is using its own re-
sources, as well as state and federal grant funding, to make
improvements. The ultimate aim of these efforts is to keep
Lake Lewisville off the 303(d) list, which would require
TMDL development to address the sources of impairment.

Watershed Approach Effectiveness

Denton assesses the effectiveness of its watershed-based
approach according to decreases in pollutant loads over
time. First, it uses the monitoring program to locate and
eliminate specific hotspots of pollution, such as discharges
from industrial facilities or drilling operations for gas wells.
Second, Denton uses monitoring activities to isolate specific

activities and land uses (i.e., construction sites) within moni-
tored watersheds to improve the enforcement of regulations.
Finally, it uses monitoring data to identify those areas where
public education should be employed to improve water qual-
ity. Denton has been very successful in educating the public
about appropriate pesticide application methods.

In addition, Denton has improved its municipal planning us-
ing the data obtained under the watershed-based monitoring
program. The data has further helped the city better imple-
ment the resulting plans and has provided it a means to
demonstrate the impacts of its municipal decisions through
improved or protected water quality. Finally, Denton has
been able to use the data and expertise gained to apply for
and receive grants that will further expand its application of
watershed-based approaches.

Lessons Learned & Next Steps

The city reports that the watershed-based approach requires
additional staff time, resources and commitment during the
initial stages of planning and implementation, and a secure
source of long-term funding, which can be challenging for
municipalities to obtain. The city also notes that it is critical
to involve the public early in a watershed-based approach.
The city reported that they were able to engage the public
by packaging watershed-based information in an easy-to-
read and understandable format. Denton was able to use the
Internet to help spread this information.

Denton has incorporated the watershed-based monitoring
and public outreach approaches into its NPDES Storm Water
Management Plan. These approaches will support compli-
ance with many of the six minimum measures required for
storm water management programs under the Phase II regu-
lations. The city also intends to continue working with TCEQ
and EPA to explore water quality trading through the section
319 grant and to propose the development a watershed-
based permit incorporating the city's storm water, pretreat-
ment, and wastewater regulatory requirements.


City of Denton. 2006a. Hickory Creek 319 Project—Meeting Information.

City of Denton. 2006b. City of Denton, Hickory Creek Watershed 319 Grant: (Draft) BMP Implementation Plan. Prepared for


Smith, Rodney. 2003. Abstract for presentation titled, City of Denton Watershed Mapping and Public Information Website.

Note: All Web references current as of July 6, 2007.