Tag Archive for: FAQs

HCFCD Flood Education Mapping Tool Contains Features Found Nowhere Else, Plus Basic Flood Education on One Page

Developed after Tropical Storm Allison in 2001, the Harris County Flood Control District Flood Education Mapping Tool’s purpose was to help Harris County residents learn the location of their properties in relation to mapped 1-percent (100-year), 0.2-percent (500-year) and coastal floodplains. The Flood Education Mapping Tool includes regularly-updated floodplain information from the Flood Insurance Rate Maps (FIRMs) for Harris County, interactive legend options, a simple map display and easy map navigation.

Easy to Use

The tool itself is easy to use and navigate. Click on Floodplains; it will show you the extent of various floodplains. Click on Backgrounds; choose the one you want. And click on Channels; it will highlight all channels in Harris County and show you their numeric IDs. The last is very useful in helping the District locate a problem you’re reporting.

Unique Ponding Feature

But the Flood Education Mapping Tool contains another feature I have found nowhere else: the Ponding button. Click on it; low areas susceptible to ponding during heavy rains will highlight in shades of reddish brown.

HCFCD’s Mapping Tool contains “ponding” feature that that shows low areas that collect water during heavy rains. Shown above, the Deerbrook Mall area in Humble.

Ponding is the collection of stormwater on streets or on undeveloped land that typically forms when rainfall exceeds the design capacity of a street’s drainage system or the land’s ability to drain. The shade of red indicates the depth of the water. Dark red indicates deep ponding and light red indicates shallow ponding – very helpful when evaluating a home purchase.

Basic Flood Education All on One Page of FAQs

The Flood Education Mapping Tool also contains a treasure trove of useful FAQs. The Flood Control District has broken them down into four main categories:

  1. Flood Insurance Rate Map (FIRM or floodplain map)
  2. Floodplains and Floodways
  3. Floodplain Status/Floodplain Determination
  4. Flood Insurance

If you want a basic flood education on a page, this is the page for you. It will help you converse knowledgeably with a flood-insurance or real-estate agent.

Flood Insurance Rate Maps

• What is a Flood Insurance Rate Map and how do I use it?

Floodplains and Floodways:

• What is a floodplain? / What is a floodway?
• What is a 1 percent (100-year) flood/floodplain? / What are my chances of flooding in a 1 percent (100-year) floodplain?
• What is a 0.2 percent (500-year) flood/floodplain? / What are my chances of flooding in a 0.2 percent (500-year) floodplain?
• What is a coastal floodplain?
• What is a Special Flood Hazard Area?
• What is meant by Base Flood Elevation?
• Who determines the boundaries of a floodplain? / What data is used to create a Flood Insurance Rate Map?

Floodplain Status/Floodplain Determination:

• Is my home located in a mapped floodplain? / Which mapped floodplain is my home in? / How do I get an official floodplain determination?
• What is an Elevation Certificate? / What is a Letter of Map Amendment? / What is a Letter of Map Revision?
• The Flood Insurance Rate Map shows that my lot is in a mapped 1 percent (100-year) floodplain, but my house sits on higher ground/is raised on pier and beam construction/is elevated. Do I still need flood insurance? / Can I obtain cheaper flood insurance?
• My home is not in a mapped 1 percent (100-year), 0.2 percent (500-year) or coastal floodplain. Does this mean I am not at risk for flooding?
• The Harris County Flood Control District is constructing a project on a bayou in my neighborhood. Will my home be out of the floodplain when it’s complete?

Flood Insurance

• Does standard homeowners insurance cover losses and damages from flooding?
• Am I required to have flood insurance? / Do I still need flood insurance if I live outside a mapped 1 percent (100-year) floodplain?
• If my home floods, will federal disaster assistance pay for all of my damages?
• Is damage from wind-driven rain or rain that comes through my roof covered by my flood insurance policy?
• How can I obtain flood insurance?
• How much does flood insurance cost? / Why is my flood insurance so expensive?
• Can I get flood insurance if I rent?

This page of FAQs is extremely well written, concise, and easy to understand. Most answers also contain links to other helpful, related sites. So you can drill down into most topics as deeply as you wish.

I’ve listed Harris County Flood Control District’s Flood Education Mapping Tool on the Links page of this web site under Floodplain Maps and Elevation, so you can find it easily in the future.

Posted by Bob Rehak on 8/30/2020

1097 Days since Hurricane Harvey

FAQs About Lowering Lake Conroe to Reduce Downstream Flood Risk

At its February 2020 board meeting, the San Jacinto River Authority (SJRA) Board of Directors will consider NOT lowering Lake Conroe during the spring and fall rainy seasons. Lake Conroe residents have mobilized to protest the lowering which they see as a costly inconvenience. They have started spreading disinformation about the policy. The SJRA Board has reportedly already received more than a hundred letters protesting the policy.

Reason for Lowering and Current Status

The strategy of lowering Lake Conroe on a seasonal basis reduces the risk of flooding downstream residents by increasing the capacity of Lake Conroe to store water. The SJRA Board of Directors and City of Houston review the strategy annually. Both entities own water rights in Lake Conroe.

The gates at Lake Conroe can release water at up too 150,000 CFS but are currently releasing 0 CFS. Lake lowering ended October 1st.

This year’s seasonal lowering of Lake Conroe ended October 1st. However, as of this morning, the lake level is down to 198.77′ MSL (mean feet above sea level). That’s 2-3 inches below the target level for the fall lowering. The lower level is due to evaporation and low rainfall; the SJRA stopped releasing water on October 1.

After Hurricane Harvey, the State of Texas called on the SJRA Board of Directors and the City of Houston to participate in regional strategies to reduce flooding. The temporary lowering of Lake Conroe has reduced  releases from Lake Conroe during storms. SJRA and downstream communities realize and understand the inconvenience that the strategy can create around Lake Conroe. We ask for understanding for the duration of this temporary mitigation strategy.

Seasonal Lake-Lowering FAQs

Who Decides?

The City of Houston and the SJRA collaborate on the decision to temporarily lower Lake Conroe for flood mitigation because it effects the water supply of both entities.

How Long Will It Continue?

Seasonal lake lowering is a temporary flood mitigation initiative to increase the capacity of Lake Conroe to catch rainfall and runoff while long-term and short-term flood mitigation strategies are implemented downstream.

The motion made by the SJRA Board states that the intent of the proposal is to provide “a near-term, temporary flood mitigation benefit while more permanent mitigation strategies, such as dredging of the lower West Fork, are completed.” 

When Does It Happen?

Seasonal lake lowering occurs twice annually – first in April/May and second in August/September.

How Much is It Lowered and for How Long?

In the spring, releases begin on April 1st. SJRA gradually reduces the level of Lake Conroe to 200’ mean feet above sea level (msl)—one foot below the normal Lake Conroe pool level of 201’ msl. Starting on June 1st, SJRA recaptures flows to restore normal lake elevation to 201’ msl. 

In the fall, releases begin on August 1st. SJRA gradually reduces the level of Lake Conroe with a goal of reaching 200’ msl by August 15th. After August 15th, gradual lowering continues with a goal of reaching (and maintaining) 199’ msl—two feet below normal pool—by August 31st. Starting October 1st, SJRA begins to capture flows to restore normal lake elevation to 201’ msl.

What If The Lake Is Already Down?

If the lake level has already dropped to the target elevation due to evaporation, no releases are made.

What if It Rains While the Lake is Already Lowered?

If a storm enters the forecast while seasonal releases are being made to lower the lake level, releases are stopped and the river is allowed to drain out until rainfall is out of the forecast.

Is There Science Behind This Policy?

Two engineering reports by Frees & Nichols from early 2018 show the benefits in terms of flood mitigation and the potential negative impacts to water supply. These reports as well as additional information about seasonal lowering can be found at: https://www.sjra.net/floodmanagement/.

Has it worked? Is there real value in terms of flood mitigation?

Yes. Looking at recent rainfall events, seasonal lowering resulted in both lower peak lake levels during storms and lower release rates from the dam.

For example, the spring 2019 seasonal lowering created an additional one foot of storage space to capture rainfall in early May 2019 when storms hit the Conroe and Lake Houston areas. Lake Conroe caught significant rainfall and runoff during the storms causing the lake to rise more than a foot. If Lake Conroe had entered this event at or near full, the peak release rate would have been higher thereby increasing the peak flow in the West Fork of the San Jacinto River. 

Is There a Benefit to Lake Conroe?

Seasonal lowering also reduces the peak Lake Conroe level during storms, which reduces negative impacts around the lake such as damage to docks and other personal property. During Harvey, several hundred homes around Lake Conroe flooded.

Data for the May event, and for all releases from the dam, including those during seasonal lowering periods, can be monitored by visiting SJRA’s home page at www.sjra.net. Click on the “Lake Operations and Rainfall Dashboard.”

What is the cost of the release?

Lake Conroe was built as a water supply reservoir in the 1970s through a partnership between SJRA and the City of Houston. Two thirds of the water in Lake Conroe belongs to the City of Houston and one third to SJRA. The City of Houston can call for the release of its water at any time, and water supply reservoirs are built to fluctuate as demands or operational needs dictate. 

Releases such as those made for dam repairs and seasonal lowering are not charged to any particular customer, therefore it is not possible to assign a value to the water released. In addition, temporary, non-customer releases do not reduce long-term water supplies, therefore they are not considered lost revenue. 

To be considered as lost revenue, releases would have to happen at a time when the SJRA could not meet demand with water from Lake Conroe. But that has not happened.

And most important, if the water supply in Lake Conroe were ever threatened, say from drought, the SJRA would not be releasing water anyway. The lake level would already be far below the target level, making a release unnecessary.

Is This a Permanent Program?

No. Seasonal lowering is a temporary flood mitigation strategy that must be reconsidered each year by the City of Houston and the SJRA Board of Directors while more permanent mitigation strategies, such as dredging of the lower West Fork, are completed. 

How Do I Make my Opinion Known to the Board?

The SJRA Board of Directors welcomes input regarding the seasonal lake lowering strategy. If you would like to contact the Board please visit: https://www.sjra.net/about/board/ or email floodmanagementdivision@sjra.net

Posted by Bob Rehak on 11/23/2019

816 Days since Hurricane Harvey