HomeMy WebLinkAboutMINUTES - 12091986 - 2.11 IS/w®O i l
TO BOARD OF SUPERVISORS
FROM: Harvey E. Bragdon Contra
Director of Community Development Costa
DATE: November 17, 1986 Cour/
SUBJECT: Urban Creeks Task Force
SPECIFIC REQUEST(S) OR RECOMMENDATION(S) Be BACKGROUND Alm JUSTIFICATION
RECOMMENDATIONS
Acknowledge receipt of the Urban Creeks Task Force report entitled "Concepts/Urban and
Rural Creeks" and refer the material to the Contra Costa General Plan Congress for their
consideration and inclusion into the revision of the County General Plan.
Acknowledge the status report of the Urban Creeks Task Force efforts on the revision of
the County ordinance and the consideration of a stream inventory and encourage the rapid
completion of the committee efforts. ,
FINANCIAL IMPACT
The Urban Creeks Task Force efforts are covered by the existing budgets of the Community
Development and Public Works Department.
REASONS FOR THE RECOMMENDATIONS/BACKGROUND
The Urban Creeks Task Force was established by the Board of Supervisors to make
recommendations on three specific work components; they are to propose wording on creek
issues for addition to the countywide General Plan revision effort, to propose revisions
to the ordinance code relating to drainage, and to help determine the scope of work for
a stream inventory for the County. Each of these efforts is discussed below:
o Proposed General Plan Wording
The Urban Creeks Task Force has completed the task of drafting wording on the
creeks issue which could be added to the Conservation Element of the
countywide General Plan revision effort currently underway. Their proposal
is entitled "Concepts/Urban and Rural Creeks" and is Attachment A to this
report. The committee spent considerable time and effort fine tuning the
wording of their report even though they recognized that the final wording in
the County plan might need to be modified to fit the style and format of that
new document. They spent this additional effort because they wished to
ensure that the concepts they developed were clearly stated and hoped the
report might serve the purpose of a background report on this subject.
I recommend that the Board acknowledge receipt of the report "Concepts/Urban
and Rural Creeks" and refer the document to the ContrA Costa General Plan
Revision Congress for their consideration and inclus'on ipto the revision of
the County General Plan.
CONTINUED ON ATTACHMENT: )!� YES SIGNATURE'
RECOMMENDATION OF COUNTY ADMINISTRATOR RECOMMET ONO COAf COMMITTEE
APPROVE OTHER
SIGNATURE(S)'.
ACTION OF F.!OARD ON December 9, 1986 APPROVED AS RECOMMENDED X OTHER
VOTE OF SUPERVISORS
1 HEREBY CERTIFY THAT THIS IS A TRUE
X UNANIMOUS (ABSENT ) AND CORRECT COPY OF AN ACTION TAKEN
AYES: NOES: AND ENTERED ON THE MINUTES OF THE BOARD
ABSENT: ABSTAIN: OF SUPERVISORS ON THE DATE SHOWN.
Community Development Department
cc: Public Works Department ATTESTED _ C�'i�„ 1 3,_l 9_ _
County Counsel PHIL BATCHELOR, CLERK OF THE BOARD OF
County Administrator SUPERVISORS AND COUNTY ADMINISTRATOR
Bud Murphy, Flood Control
M382/7-83 D
BY {�(it,�/ ,DEPUTY
- 2 -
o Ordinance Revisions
The task force has spent considerable time reviewing and revising the
portions of the County ordinance code dealing with creeks. Revisions to
Chapter 914 of the ordinance code covering drainage and Chapter 1010 of the
subdivision ordinance dealing with streams have been drafted. Those proposed
revisions are currently being reviewed by County Counsel 's Office. Upon
completing that review, the task force will take the comments received and
create a finalized proposal ; when complete I will forward the ordinance for
consideration by the Board of Supervisors. It is anticipated that the
committee will complete that effort by the end of this year.
o Stream Inventory
The task force favors the undertaking of a stream inventory and has been
working with our staff and that of the Public Works Department to prepare a
generalized work program. That effort is nearing completion.
The Urban Creeks Task Force should be completing its efforts, hopefully, by the
end of the year or very early in 1987.
r
CONCEPTS/URBAN AND RURAL CREEKS
When Contra Costa County was sparsely populated and predominantly rural ,
creeks and streams flowed uninterrupted from the coastal hills to the Bay and
Delta. These watercourses supported a wide variety of plant, animal , and
aquatic life. Riparian vegetation and streamside habitats minimized erosion,
sustained perennial streams, contributed to groundwater reserves, moderated
temperature extremes and provided an attractive and pleasant environment. It
is of benefit to County residents to preserve vestiges of this pre-settlement
environment and to actively work toward re-establishing this environmental
heritage.
As portions of the County changed from agricultural land to urban uses,
permeable ground surfaces were replaced with impervious surfaces. Paving,
roofs, and efficient drainage systems reduced the percent of rainfall
percolating into the ground and increased the volume and velocity of surface
runoff carried to the creek channels. This resulted in increased flood
frequency and severity, in channel cutting and loss of vegetation in upper
watersheds, and silting in lower channels.
Creeks and streams were relocated and realigned to accommodate increased
flows, channels were increased in width and depth, channels were lined with
concrete or riprap, and creeks were placed in conduits and culverts. Although
these improvements have been effective in transporting, stormwater runoff, in
reducing flooding, and reducing property damage, these benefits have come at
the expense of difficult to replace and sometimes irreplaceable natural
channels and native riparian habitat.
Traditionally, the more efficient the drainage system feeding into a natural
watercourse, the greater the damage to natural waterways and streamside vege-
tation and the greater the downstream flood damage risk. The continued use of
traditional drainage facilities in individual development projects exacerbates
these problems. Many undeveloped properties lie upstream from established
urban development and each new development project which increases peak run-
off, although seemingly insignificant, contributes to a future need to make
improvements to existing downstream public flood control facilities and
natural channels at substantial cost to county residents.
The use of alternate stormwater management techniques such as the floodplain,
the leveed floodway, the bypass channel and the detention basin, can either
lessen or eliminate completely the need for these improvements, reducing
public costs and providing a more diverse and attractive environment for
county residents.
Floodplain management programs are the most efficient and least costly means
of reducing flood damages, but must be instituted before extensive development
takes place. Floodplain management regulates land use in flood prone areas.
Only those land uses which will not suffer heavy losses from flooding are
permitted and developers are required to floodproof new improvements. The net
effect is to provide a .considerable degree of reduction in flood damage at
very little public cost.
Concepts/Urban and Rural Creeks Page 2
The detention basin, leveed floodway, and the bypass channel are runoff
management techniques which are useful in circumstances where rights-of-way
are available. The leveed floodway and open bypass are particularly
appropriate in areas such as east county, where there is opportunity for
coordinated land use planning. The underground bypass pipeline is best suited
to situations where land is scarce and there is a need to divert quantities of
water away from natural watercourses during periods of heavy rainfall . Under
this approach, watercourses remain in a natural state and are not subjected to
increased flooding or erosion while the ground surface over the pipeline can
placed in productive use.
Detention basins function by collecting and storing water in a reservoir on
the site of a new development or elsewhere in a watershed. Stored water is
released gradually to reduce the peak flow discharge into the watercourse to
which it drains. Where soil conditions are favorable, detention basins can
also permit percolation into the ground, thus augmenting diminishing groundwa-
ter reserves. Detention basins can be landscaped and are often adaptable to
multiple use, such as parks, playing fields, or parking areas, when storm
water runoff is not being impounded. Properly designed basins can be
attractive assets in residential neighborhoods throughout the county. Deten-
tion basins are often less expensive than comparable flood protection but do
involve operational and maintenance costs which may partially offset those
savings.
While it may be desirable to keep all of the remaining.-creeks and streams in
their natural state, this is not always possible. Within existing developed
areas, watercourse structural modifications are often the only viable alterna-
tive. The lack of available land within a built-up urbanized area, as well as
i,ts high cost, may rule out the possibility of keeping a watercourse in its
natural state. Where this is the case, alternate structural approaches can be
utilized which are designed to be compatible with their environment. Instead
of riprap and concrete, slope protection devices can be used to stabilize
banks. Landscaping should also be used to soften the visual impact of
structurally modified watercourses.
Control of flooding is not the only ,, drainage concern. With increased
development and stormwater runoff, a wide variety of nutrients and toxic
substances have been introduced into County waters. Nutrient wastes in the
form of sewage, agricultural fertilizers,' and manure lead to reduced dissolved
oxygen in surface waters and limit the capacity of water to support aquatic
organisms. Toxic substances, such as industrial wastes, insecticides and
herbicides, can poison wildlife and become concentrated in the food chain.
Both types of pollutants can adversely affect the quality of groundwater.
Erosion and sedimentation often inflict heavy public costs for flood control ,
harbor and channel dredging, post-flood clearing and private property damage,
besides damaging aquatic life and carrying toxic substances into public and
private water supplies. Design and construction techniques have been devel-
oped which are cost effective and essential to erosion and sedimentation
reduction. All projects for which graded earth is left exposed during the
rainy season should be required to take erosion control measures similar to
those developed by the Soil Conservation Service.
Concepts/Urban and Rural Creeks Page 3
The Contra Costa County Flood Control and Water Conservation District Act
created a Flood Control District empowered to control flood and storm waters;
to conserve such waters for beneficial and useful purposes by spreading,
storing, retaining, causing to percolate or saving or conserving in any other
manner; to provide flood and storm water protection for watercourses,
watersheds, public highways, life and property; to obtain, retain and reclaim
drainage, storm, flood and other water for beneficial uses; and to avoid waste
of and diminution in the water supply.
Even though the District has no influence over the County or its municipali=
ties regarding land use and planning ,matters, the District does develop
drainage plans for entire watersheds which cross jurisdictional boundaries.
The District also provides information and recommendations to cities and other
County departments on drainage plans and the capacity of existing waterways
and drainage facilities. Moreover, the District reviews subdivision improve-
ment plans when major and secondary watercourses are involved.
The District, through its expertise, plans and policies can greatly influence
the type and multiple use of drainage improvements made within the county and
its municipalities. The District is in a unique position to provide
countywide leadership in drainage matters and effectuate a transition from
primarily traditional drainage solutions to solutions which incorporate more
innovative measures, measures which control flooding while protecting natural
watercourses and native vegetation resources for the benefit of all county
residents.
There is a need to provide enhanced opportunities for public access to creeks,
streams, and drainage channels, where conditions and liability constraints
permit. Total County population will continue to increase and with it the
demand for recreation facilities. Drainage features which can be made into
parks or open space or incorporated as assets into new development projects,
will be used and appreciated by present and future county residents.
The environmental awareness of county residents, increasingly scarce natural
resources, reduced opportunities in urban areas to provide inexpensive recrea-
tion facilities close to residential areas, the escalating costs of public
drainage improvements, the identified benefits from natural watercourse and
streamside vegetation preservation and enhancement, declining county groundwa-
ter resources, and the refinement and successful application of various
alternate drainage management techniques in the county and elsewhere, all
support the reevaluation of existing drainage plans.
A reevaluation of existing plans should be a joint effort of the Flood Control
District and the Community Development Department. An updated inventory of
existing watercourse resources, with an emphasis on remaining natural channels
and riparian vegetation, is of highest priority to a new planning effort.
After an inventory is completed, Stream Conservation Areas should be estab-
lished to protect critical watercourses and establish equitable procedures for
new development.
Concepts/Urban and Rural Creeks Page 4
The Community Development Department can be helpful by revising current
General Plan land use policies and designations to be consistent with the
preservation of watercourses and by ensuring that watercourses are given
proper consideration in development projects. Land use planning can also be
helpful by noting areas in which unusual erosion control techniques should be
applied and by defining local agency responsibilities for enforcement of soil
conservation practices in urban areas.
The assistance and concerns of other agencies and organizations, such as
municipalities, the East Bay Regional Park District, county service areas and
local community groups, should be sought in the revision of existing plans to
assure broad-based support and insure that plans are practical and achievable.
JWC/jn
t2:concepts.urb
POLICIES/URBAN AND RURAL CREEKS
In order to maintain the ecology and hydrology of creeks and streams and
provide an amenity to the public, while at the same time preventing flooding,
erosion and danger to life and property, the following policies should be
followed:
I . Protection of Riparian Zones:
A. Creeks and streams are important and irreplaceable natural resourc
es. They should be retained in their natural state whenever
possible to maintain water quality, wildlife diversity, aesthetic
values, and recreation opportunities.
B. The County ordinance code should provide for protection of water-
courses and riparian vegetation, and enhancement of the natural
environment.
C. The County should work with appropriate agencies to census the
County's riparian resources and to identify areas warranting
preservation and enhancement.
D. The County should wherever possible enhance remaining natural water-
courses to restore them as wildlife habitats.
E. The County should work toward the preservation and re-establishment
of the fisheries in the streams within the County.
F. The County should develop a program that fosters the participation
of public agencies, private organizations and individuals in the
development of watershed management practices that reduce soil loss
and excessive runoff (i .e. control of grazing in upper watersheds,
timing of release of water from upstream dams, revegetation of upper
watersheds) , and that minimize the effect on downstream areas.
II . New Development along Natural Watercourses:
A. Setback areas should be provided along natural creeks and streams in
areas planned for urbanization. Deeded development rights on lands
within the setback areas shall be granted to a governmental agency
to insure their preservation.
B. New parcels which are created should include adequate space outside
of the watercourses' setback areas for pools, patios, and
appurtenant structures so that property owners won't place improve-
ments within the areas which require protection.
Policies/Urban and Rural Creeks Page 2
C. Natural watercourses should be integrated into new development in
such a way that they are accessible and provide a positive visual
element.
D. Where practical , major new developments should be required to
practice on-site water control" so that post-development runoff does
not exceed the amount of runoff from the property in its saturated
pre-development condition. Flow metering devices, detention basins,
permeable pavements (to absorb runoff) , softscape surfaces, and
other methods should be employed. Where practical , detention basins
should be designed for multiple uses such as parks, playing fields,
parking areas, etc. when not used for holding water.
E. Every effort should be made to preserve, maintain, and enhance all
existing native riparian habitat within the County. When riparian
habitat must be modified to accommodate new development, an equiva-
lent portion of such habitat should be restored and enhanced to as
near a natural state as possible. The restoration should take place
on the same watercourse, or on a watercourse close to the area of
loss. The determination that no opportunity for restoration exists
should be made by the Planning Agency. If such a determination is
made, the developer should adequately compensate for the amount
equal to established value of the loss to a countywide mitigation
fund.
F. Restoration and revegetation of watercourses with native vegetation
should be required.
III . Flood Control
A. All agencies should take aesthetic, environmental , and recreational
benefits, in addition to capital , operation and maintenance costs,
into full consideration when determining the costs and benefits of
alternative means of flood control .
B. Floodplain management rather than structural improvements is the
preferred method of handling potential flooding and erosion control
problems.
C. When the County receives its Federal Insurance Rate Maps (FIRM) , it
should move rapidly to implement the appropriate ordinances.
D. Flood-proofing of structures should be required in any area subject
to flooding; this should occur both adjacent to watercourses as well
as in the Delta or along the waterfront.
E. Flood Control Zone plans should be developed based on the concepts
found in this general plan, and as adopted zone plans are revised,
they should be brought into conformity with these concepts.
Policies/Urban and Rural Creeks Page 3
F. As an alternative to structural modifications of watercourses,
bypass pipelines and acquisition of floodplain easements should be
used whenever possible.
G. Instead of extensive riprap or concrete lining to stabilize creek
banks, gabions could be used.
H. Watershed plans should be developed which encourage the development
of detention basins, stock ponds, and erosion control ponds in the
open space areas of the County which would serve to reduce the peak
flows, but would also provide for additional habitat enhancement.
They would be particularly appropriate on publicly owned lands and.
within park lands.
I . Portions of channels which have been structurally modified for flood
control an`d erosion prevention have the potential to be used as
urban open spaces as linear parks and trails and should be evaluated
for those purposes by the County municipalities and recreations
agencies.
J. Protection of agricultural lands from flooding should be considered
an important public benefit if done at an appropriate economic level
to maintain agricultural use.
K. Public participation should be encouraged in the design of major
flood control projects.
L. The County should limit. shoreline development, on lands planned for
open space, to minor structures (except for recreational facilities.)
for properties that fall below the highest tide of record, including
wetlands, seasonal wetlands, and lands defined as within the 100
year flood zone, unless adequate measures to limit possible flooding
have been incorporated into the project design.
IV. Maintenance:
A. Property owners are required by law to maintain watercourses that
are within their property. The County, and each municipality should
adopt an ordinance preventing property owners from causing an
obstruction in a watercourse and also establish a code enforcement
program adequate to assure compliance with the ordinance.
B. Watercourses are subject to periodic maintenance, such as desilting
and the clearing of excess vegetation to assure an adequate water
flow. Existing maintenance practices should be reviewed and modi-
fied so that natural vegetation is allowed to remain where possible.
Maintenance should be scheduled to minimize disruption of wildlife
breeding cycles and riparian vegetation.
Policies/Urban and Rural Creeks Page 4
C. The application of integrated pest management methods in the
maintenance of flood control channels should be encouraged.
D. In order to control erosion within natural watercourses, check dams
and drop structures could be used on those watercourses where
capacity permits.
E. The County should work with appropriate agencies to develop an
inexpensive program for the restoration of riparian vegetation in
rural creeks where grazing activities are reducing the extent of the
vegetation and eroding channel banks.
JWC/jn
t2:policies
11/24/86