The intent of this Technical standard is to preserve natural and existing drainage and 100% of the habitat areas within the protected riparian areas. To accomplish this, the regulations provide for two options: (1) no encroachment into the regulated area or (2) if encroachment is proposed into the regulated area, submittal of an environmental resource report in conformance with this section, and, if encroachment is proposed into the protected riparian areas, development in conformance with development restrictions and mitigation requirements in this section.
A. No Encroachment in Regulated Areas
For projects where there will be no encroachment within the regulated areas, development is not restricted by this section except as provided herein and except that the regulated areas shall be identified on the
plan, plat or development plan in a surveyable manner. This plan, or a separate plan, shall also indicate the proposed location of the temporary fencing which is required to protect the protected riparian areas during construction. The conditions for development with no encroachment are as follows:
1. ERZ Watercourses. Applications within the ERZ watercourses described in Section 4-02.2.2.A, ERZ Watercourses, above that propose a project with no encroachment into the regulated area are required to indicate the 100-year floodplain on the plans submitted through the applicable process, accompanied by a floodplain report verifying the floodplain limits.
2. WASH Watercourses. Applications for WASH watercourses as described in Section 4-02.2.2.B, WASH Watercourses, above that propose a project with no encroachment into the regulated area, are required to indicate the top of bank or ten-year flood boundary and the 50-foot study area beyond those lines on the plans submitted through the applicable process, accompanied by a floodplain report verifying the floodplain limits.
3. Regulatory Floodplain Watercourses. Applications within the regulatory floodplain watercourses described in Section 4-02.2.2.C, Regulatory Floodplain Watercourses, above that propose a project with no encroachment into the regulated area are required to indicate the 100-year floodplain on the plans submitted through the applicable process, accompanied by a floodplain report verifying the floodplain limits.
4. Floodplain Restoration. Revegetation, restoration or enhancement under this subsection shall not constitute “encroachment” under applicable codes. A Floodplain Restoration Plan must be prepared and approved in conformance with this subsection in order to undertake floodplain revegetation, restoration or enhancement. For areas within the regulated areas that are to remain as open space after development, revegetation and restoration of the open spaces areas is encouraged, but not required, to enhance the riparian resources within the regulated area as follows:
a. Voluntary revegetation, restoration or enhancement should create or restore the riparian habitat through the planting of native trees, shrubs, and understory species and the distribution of seed mix native to the
or a comparable reference
to the extent possible. Additional native species may be used in the restoration effort if they are typical of intact riparian habitat in areas similar to the
.
b. Revegetation, restoration or enhancement efforts should include native plant material salvaged from the
or preserved in place.
c. Development and revegetation, restoration or enhancement efforts shall conform to the city’s policies regarding
.
B. Encroachment in Regulated Areas
If the project proposes encroachment within the regulated areas, it shall conform to the following.
1. Environmental Resource Report. Applicants are required to submit an Environmental Resource Report as defined in Section 11.4.6 of the UDC. The supporting material for preparation of the Environmental Resource Report is based on information from the Hydrologic Data and Wash Information maps on the Tucson Department of Transportation internet web site: The Critical and Sensitive Wildlife Habitat Map and Report, the Mayor and Council Interim Watercourse Improvement Policy and subsequent adopted policies, the Tucson
Management Study, the following Basin Management Plans: 1) West Branch, Santa Cruz; 2) Houghton East; 3) Este Wash; and 4) Arroyo Chico. the Tucson
Management Study, Phase II and field observation. An application may request that an element listed below be waived or that the report address only a specified area where a full report is not applicable to the proposed encroachment. DSD may grant such waivers where the elements or full report are not required by code. The Environmental Resource Report must include:
a. A table of contents, indicating all information by page or map number;
b. The location of the 100-year floodplain on, adjacent to, and a minimum of 200 feet upstream and downstream of the proposed development;
c. Soil conditions in and adjacent to the watercourse, and the
potential;
d. Existing rights-of-way or easement dedication along the wash for a distance of 500 feet upstream and downstream of the proposed development;
e. The existing and proposed ownership of any drainageway facilities on or adjacent to the
and identification of the persons responsible for the maintenance of such facilities;
f. Previous hydraulic/hydrology studies or maps prepared for the watershed and relevant floodplain studies, delineations, LOMR applications and approvals affecting the project
;
g. Groundwater recharge potential at this location;
h. Sediment transport characteristics along the watercourse centered on this location;
i. Existing and proposed utilities to and across the
;
j. Any other elements that may be characteristic of the watercourses on or adjacent to the
;
k. A map indicating the boundaries of the proposed development and its relationship to any watercourses designated on the Hydrologic Data and Wash Information maps on the Tucson Department of Transportation internet web site;
l. An aerial photograph no more than two years old, with flight date, north arrow, project
boundaries, floodplain delineation, protected riparian area and a scale no smaller than one inch equals 200 feet. DSD staff may request an aerial photograph with topographic information;
m. Ground
photographs from points identified on submitted plans that document the protected riparian area and any areas within the protected riparian area to be disturbed;
n. Any applicable Basin Management Plan, which recommends that watercourses remain in a natural state, shall be referenced in the Report;
o. A map identifying the type, location and extent of all riparian resources and plant associations, including but not limited to, hydroriparian habitat, mesoriparian habitat, xeroriparian habitat, tobosa grass habitat, mesquite bosques, individual cacti and trees with a caliper of four inches or greater, and all saguaros, regardless of size. The identification of riparian habitat shall cover the entire
and is not limited to the regulated areas;
p. Delineation of the proposed protected riparian area and a statement of the total area of the
, the total area of the protected riparian area, the area within the regulated area, and the total of any areas proposed to be disturbed within the protected riparian areas;
q. Delineation of the riparian resources and any proposed open space linkages or facilities recommended by parks, recreation, open space, and trails plan, for a distance of 500 feet or one-half times the length of the watercourses on the property, whichever is greater, both upstream and downstream from the property. This shall be based on information that is available from aerial photographs, the Hydrologic Data and Wash Information maps on the Tucson Department of Transportation internet web site and other public sources;
r. A Plant Inventory and aerial photographs of individual woody plants and cacti rooted within the encroachment area. Both living and dead plants and cacti should be inventoried. The Plant Inventory List shall include an identification number, genus and species, and size of all plants having basal trunk diameters greater than two inches. All plants inventoried are to be shown on an aerial photograph at a minimum scale of one inch equals 60 feet;
s. A delineation, map and assessment on an aerial photograph of habitat types noted on the Critical and Sensitive Wildlife Habitat Map;
t. A written or mapped assessment of significant densities of wildlife by species;
u. A description of the impact of the encroachment on riparian resources within the property and on the adjacent property as identified in subsection q above;
v. A written statement from the regional office of the Arizona Game and Fish Department regarding any impacts to fish and wildlife;
w. A draft Mitigation Plan in conformance with subsection 3 below if development is proposed within the protected riparian areas; and,
x. Other landscaping requirements established in Chapter 23 of the Tucson Code.
2. Development Restrictions. All development within the protected riparian area shall be reviewed to insure that there is no unnecessary disturbance of the riparian resources. Development that is outside of the protected riparian area but within the regulated area is not subject to this subsection. Necessary development shall include only the crossing of riparian habitats with roadways, bikeways, paved walkways and utilities as listed below where there is no viable alternate crossing available and the crossing is necessary for the reasonable development of the property. A written explanation as to why the development is necessary shall be submitted with the appropriate plans. Development that is permitted as necessary is subject to the following conditions:
a. Roadway, bike path, and paved walkway improvements and utility encroachments will cross the riparian habitat areas, not to run parallel to the protected riparian areas;
b. Encroachments that cross the protected riparian area shall be located and constructed to minimize disturbance of the habitat and wildlife movement;
c. All utilities in protected riparian area areas will be located underground; utilities will be placed either in proposed or existing public right of way along roadway, bike path, or paved walkway improvements or within approved easements.
d. Any roadway, bike path, or paved walkway improvement must be constructed in such a manner as to provide means for safe and accessible passage for wildlife.
e. Concrete, rock veneer and soil cement bank treatment for the culvert and associated drainage may be permitted within the public right of way upon
of the City Manager.
f. For WASH watercourses, concrete, rock veneer and soil cement bank treatment for the culvert that is outside of the proposed or existing public right of way shall be permitted only with the
of the Mayor and Council. For all other watercourses, concrete, rock veneer and soil cement should not be used where there is any practicable alternative.
g. Where a roadway, paved walkway, or bike path improvement or utility encroachment occurs within the protected riparian area, mitigation in conformance with Section 4-02.2.5.B.3, Mitigation Plans, shall be provided.
h. Temporary Fencing Required. No
,
, or construction will occur on a project
which includes areas designated as protected riparian area to be retained in a natural state until those designated areas are temporarily fenced. The temporary fencing shall remain in place during all phases of construction that could affect the protected riparian area.
3. Mitigation Plan. Where any development, except planting solely for revegetation, restoration or enhancement with an approved Floodplain Restoration Plan, encroaches within the protected riparian areas, mitigation will be required. A mitigation report shall be submitted with the Environmental Resource Report demonstrating that the proposed mitigation is in conformance with this subsection and applicable codes.
a. Mitigation Plans shall address the following:
1. Revegetation should recreate the lost functions and values of the riparian habitat through the planting of native trees, shrubs, understory plants and seed mix native to the
which will result in comparable habitat that is equal to the predisturbance habitat in area, plant density, diversity, and volume on the net
. Revegetation should be conducted over a sufficient area to accomplish the following mitigation ratios while accomplishing the specified plant density, diversity and volume of the impacted area.
i. Trees with basal trunk diameters ranging from two to four inches and shrubs should be replaced at a two to one ratio.
ii. Trees with basal trunk diameters larger than four inches should be replaced at a three to one ratio.
iii. Cacti, except cholla or prickly pear, should be replaced at a two to one ratio.
iv. Cottonwood, willow, walnut, sycamore, arizona ash, ironwood and canyon hackberry (Celtis reticulata) should not be removed. If removal is unavoidable and no other practicable alternative exists, then these plants shall be replaced by large, boxed trees at a three to one ratio and provided with at least three years of supplemental irrigation and care to ensure healthy establishment. Replacement trees shall be in 36-inch boxes and shall be at least eight to ten feet tall and at least two and one-half inches in diameter, measured three feet above the ground.
2. Mitigation can be designed to provide native riparian habitat that is appropriate for the location and soil conditions, even where that may be enhanced beyond the predisturbance habitat in terms of native habitat area, plant density, diversity and volume on the net
.
3. Revegetation should include native plant material salvaged from the
.
4. Development and revegetation shall conform to the city’s policies regarding
.
b. Mitigation Plans shall include:
1. A development plan/
plan, including landscape plans, indicating proposed development; floodplain encroachment locations; location of mitigation areas; techniques used for mitigating impacts to, or preservation of, natural areas; specifications for restoration and revegetation of disturbed areas; and general compliance with the applicable standards;
2. Landscape plans that document compliance with the mitigation plan requirements. A summary of mitigation and preservation requirements shall be included on the plans; and,
3. A description of the maintenance program that provides for revegetated/restored or enhanced areas. The program shall include irrigation to establish native plants, provide for regular inspection, removal of invasive species, and native plant replacement as necessary to successfully establish the mitigation habitat. All mitigation plantings and related improvements shall be maintained for at least three years following installation.